Standardize string property initialization to string.Empty

Replaced String.Empty and null! with string.Empty for string properties
in CatalogReadDto, CatalogWriteDto, and VwmyCatalog classes. This
ensures consistent initialization and helps prevent null reference
issues across the codebase.

DbFirst.API/Controllers/CatalogsController.cs

@@ -1,7 +1,6 @@
 using DbFirst.Application.Catalogs;
 using DbFirst.Application.Catalogs.Commands;
 using DbFirst.Application.Catalogs.Queries;
-using DbFirst.Domain;
 using MediatR;
 using Microsoft.AspNetCore.Mvc;
 
@@ -37,7 +36,7 @@ public class CatalogsController : ControllerBase
     }
 
     [HttpPost]
-    public async Task<ActionResult<CatalogReadDto>> Create(CatalogWriteDto dto, CancellationToken cancellationToken)
+    public async Task<ActionResult<CatalogReadDto>> Create([FromBody]CatalogWriteDto dto, CancellationToken cancellationToken)
     {
         var created = await _mediator.Send(new CreateCatalogCommand(dto), cancellationToken);
         if (created == null)
@@ -48,19 +47,8 @@ public class CatalogsController : ControllerBase
     }
 
     [HttpPut("{id:int}")]
-    public async Task<ActionResult<CatalogReadDto>> Update(int id, CatalogWriteDto dto, CancellationToken cancellationToken)
+    public async Task<ActionResult<CatalogReadDto>> Update(int id, [FromBody] CatalogWriteDto dto, CancellationToken cancellationToken)
     {
-        var current = await _mediator.Send(new GetCatalogByIdQuery(id), cancellationToken);
-        if (current == null)
-        {
-            return NotFound();
-        }
-        if (dto.UpdateProcedure == CatalogUpdateProcedure.Update &&
-            !string.Equals(current.CatTitle, dto.CatTitle, StringComparison.OrdinalIgnoreCase))
-        {
-            return BadRequest("Titel kann nicht geändert werden.");
-        }
-
         var updated = await _mediator.Send(new UpdateCatalogCommand(id, dto), cancellationToken);
         if (updated == null)
         {

DbFirst.API/Controllers/LayoutsController.cs

@@ -2,6 +2,7 @@ using System.Text;
 using DbFirst.Application.Repositories;
 using DbFirst.Domain.Entities;
 using Microsoft.AspNetCore.Mvc;
+using DbFirst.Application.Layouts;
 
 namespace DbFirst.API.Controllers;
 
@@ -83,12 +84,4 @@ public class LayoutsController : ControllerBase
             LayoutData = layoutData
         };
     }
-
-    public sealed class LayoutDto
-    {
-        public string LayoutType { get; set; } = string.Empty;
-        public string LayoutKey { get; set; } = string.Empty;
-        public string UserName { get; set; } = string.Empty;
-        public string LayoutData { get; set; } = string.Empty;
-    }
 }

DbFirst.API/Controllers/MassDataController.cs

@@ -50,7 +50,7 @@ public class MassDataController : ControllerBase
     }
 
     [HttpPost("upsert")]
-    public async Task<ActionResult<MassDataReadDto>> Upsert(MassDataWriteDto dto, CancellationToken cancellationToken)
+    public async Task<ActionResult<MassDataReadDto>> Upsert([FromBody]MassDataWriteDto dto, CancellationToken cancellationToken)
     {
         var result = await _mediator.Send(new UpsertMassDataByCustomerNameCommand(dto), cancellationToken);
         return Ok(result);

DbFirst.API/Dashboards/DashboardChangeNotifier.cs

@@ -6,14 +6,23 @@ namespace DbFirst.API.Dashboards;
 public class DashboardChangeNotifier : IDashboardChangeNotifier
 {
     private readonly IHubContext<DashboardsHub> _hubContext;
+    private readonly ILogger<DashboardChangeNotifier> _logger;
 
-    public DashboardChangeNotifier(IHubContext<DashboardsHub> hubContext)
+    public DashboardChangeNotifier(IHubContext<DashboardsHub> hubContext, ILogger<DashboardChangeNotifier> logger)
     {
         _hubContext = hubContext;
+        _logger = logger;
     }
 
-    public void NotifyChanged()
+    public async Task NotifyChangedAsync()
     {
-        _ = _hubContext.Clients.All.SendAsync("DashboardsChanged");
+        try
+        {
+            await _hubContext.Clients.All.SendAsync("DashboardsChanged");
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to notify dashboard clients.");
+        }
     }
 }

DbFirst.API/Dashboards/DashboardConfiguratorFactory.cs

@@ -0,0 +1,115 @@
+using DbFirst.Domain.Entities;
+using DevExpress.DashboardCommon;
+using DevExpress.DashboardWeb;
+using DevExpress.DataAccess.Json;
+using System.Xml.Linq;
+
+namespace DbFirst.API.Dashboards;
+
+public static class DashboardConfiguratorFactory
+{
+    public static DashboardConfigurator Create(
+        IServiceProvider serviceProvider,
+        IConfiguration configuration,
+        IWebHostEnvironment environment)
+    {
+        // Den gesamten Inhalt des Lambdas hierher verschieben
+        // serviceProvider, configuration, environment statt builder.* verwenden
+
+        var dashboardsPath = Path.Combine(environment.ContentRootPath, "Data", "Dashboards");
+        Directory.CreateDirectory(dashboardsPath);
+
+        var defaultDashboardPath = Path.Combine(dashboardsPath, "DefaultDashboard.xml");
+        if (!File.Exists(defaultDashboardPath))
+        {
+            var defaultDashboard = new Dashboard();
+            defaultDashboard.Title.Text = "Default Dashboard";
+            defaultDashboard.SaveToXml(defaultDashboardPath);
+        }
+
+        var dashboardBaseUrl = configuration["Dashboard:BaseUrl"]
+            ?? configuration["ApiBaseUrl"]
+            ?? configuration["ASPNETCORE_URLS"]?.Split(';', StringSplitOptions.RemoveEmptyEntries).FirstOrDefault()
+            ?? "https://localhost:7204";
+
+        dashboardBaseUrl = dashboardBaseUrl.TrimEnd('/');
+
+        var catalogsGridDashboardPath = Path.Combine(dashboardsPath, "CatalogsGrid.xml");
+        if (!File.Exists(catalogsGridDashboardPath))
+        {
+            var dashboard = new Dashboard();
+            dashboard.Title.Text = "Catalogs (Dashboard Grid)";
+
+            var catalogDataSource = new DashboardJsonDataSource("Catalogs (API)")
+            {
+                ComponentName = "catalogsDataSource",
+                JsonSource = new UriJsonSource(new Uri($"{dashboardBaseUrl}/api/catalogs"))
+            };
+
+            dashboard.DataSources.Add(catalogDataSource);
+
+            var grid = new GridDashboardItem
+            {
+                DataSource = catalogDataSource,
+                Name = "Catalogs"
+            };
+
+            grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.Guid))) { Name = "Id" });
+            grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.CatTitle))) { Name = "Titel" });
+            grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.CatString))) { Name = "String" });
+            grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.AddedWho))) { Name = "Angelegt von" });
+            grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.AddedWhen))) { Name = "Angelegt am" });
+            grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.ChangedWho))) { Name = "Geändert von" });
+            grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.ChangedWhen))) { Name = "Geändert am" });
+
+            dashboard.Items.Add(grid);
+
+            var layoutGroup = new DashboardLayoutGroup { Orientation = DashboardLayoutGroupOrientation.Vertical };
+            layoutGroup.ChildNodes.Add(new DashboardLayoutItem(grid));
+            dashboard.LayoutRoot = layoutGroup;
+
+            dashboard.SaveToXml(catalogsGridDashboardPath);
+        }
+
+        DashboardConfigurator configurator = new DashboardConfigurator();
+
+        var connectionString = configuration.GetConnectionString("DefaultConnection") ?? string.Empty;
+        var notifier = serviceProvider.GetRequiredService<IDashboardChangeNotifier>();
+        var dashboardStorage = new SqlDashboardStorage(connectionString, "TBDD_SMF_CONFIG", notifier: notifier);
+        configurator.SetDashboardStorage(dashboardStorage);
+
+        DataSourceInMemoryStorage dataSourceStorage = new DataSourceInMemoryStorage();
+        DashboardJsonDataSource jsonDataSourceUrl = new DashboardJsonDataSource("JSON Data Source (URL)");
+        jsonDataSourceUrl.JsonSource = new UriJsonSource(
+                new Uri("https://raw.githubusercontent.com/DevExpress-Examples/DataSources/master/JSON/customers.json"));
+        jsonDataSourceUrl.RootElement = "Customers";
+        dataSourceStorage.RegisterDataSource("jsonDataSourceUrl", jsonDataSourceUrl.SaveToXml());
+
+        var catalogsJsonDataSource = new DashboardJsonDataSource("Catalogs (API)")
+        {
+            ComponentName = "catalogsDataSource",
+            JsonSource = new UriJsonSource(new Uri($"{dashboardBaseUrl}/api/catalogs"))
+        };
+        dataSourceStorage.RegisterDataSource(catalogsJsonDataSource.ComponentName, catalogsJsonDataSource.SaveToXml());
+        dataSourceStorage.RegisterDataSource(catalogsJsonDataSource.Name, catalogsJsonDataSource.SaveToXml());
+
+        configurator.SetDataSourceStorage(dataSourceStorage);
+
+        EnsureDashboardInStorage(dashboardStorage, "DefaultDashboard", defaultDashboardPath);
+        EnsureDashboardInStorage(dashboardStorage, "CatalogsGrid", catalogsGridDashboardPath);
+
+        return configurator;
+    }
+
+    private static void EnsureDashboardInStorage(IEditableDashboardStorage storage, string id, string filePath)
+    {
+        var exists = storage.GetAvailableDashboardsInfo().Any(info => string.Equals(info.ID, id, StringComparison.OrdinalIgnoreCase));
+        if (exists || !File.Exists(filePath))
+        {
+            return;
+        }
+
+        var doc = XDocument.Load(filePath);
+        storage.AddDashboard(doc, id);
+    }
+}

DbFirst.API/Dashboards/IDashboardChangeNotifier.cs

@@ -2,5 +2,5 @@ namespace DbFirst.API.Dashboards;
 
 public interface IDashboardChangeNotifier
 {
-    void NotifyChanged();
+    Task NotifyChangedAsync();
 }

DbFirst.API/Dashboards/SqlDashboardStorage.cs

@@ -100,7 +100,7 @@ public sealed class SqlDashboardStorage : IEditableDashboardStorage
 
         connection.Open();
         command.ExecuteNonQuery();
-        _notifier?.NotifyChanged();
+        _ = _notifier?.NotifyChangedAsync();
         return id;
     }
 
@@ -122,7 +122,7 @@ public sealed class SqlDashboardStorage : IEditableDashboardStorage
             throw new ArgumentException($"Dashboard '{dashboardId}' not found.");
         }
 
-        _notifier?.NotifyChanged();
+        _ = _notifier?.NotifyChangedAsync();
     }
 
     public void DeleteDashboard(string dashboardId)
@@ -133,6 +133,6 @@ public sealed class SqlDashboardStorage : IEditableDashboardStorage
 
         connection.Open();
         command.ExecuteNonQuery();
-        _notifier?.NotifyChanged();
+        _ = _notifier?.NotifyChangedAsync();
     }
 }

DbFirst.API/DbFirst.API.csproj

@@ -17,7 +17,6 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.6.2" />
-    <PackageReference Include="MediatR.Extensions.Microsoft.DependencyInjection" Version="11.1.0" />
   </ItemGroup>
 
   <ItemGroup>

DbFirst.API/Middleware/ExceptionHandlingMiddleware.cs

@@ -1,5 +1,4 @@
-using System.Net;
-using System.Text.Json;
+using Microsoft.AspNetCore.Mvc;
 
 namespace DbFirst.API.Middleware;
 
@@ -20,33 +19,35 @@ public class ExceptionHandlingMiddleware
         {
             await _next(context);
         }
+        catch (InvalidOperationException ex)
+        {
+            _logger.LogWarning(ex, "Domain validation error");
+            await WriteProblemAsync(context, StatusCodes.Status400BadRequest, "Eingabe ungültig", ex.Message);
+        }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Unhandled exception");
-            await WriteProblemDetailsAsync(context, ex);
+            await WriteProblemAsync(context, StatusCodes.Status500InternalServerError, "Serverfehler", ex.Message);
         }
     }
 
-    private static async Task WriteProblemDetailsAsync(HttpContext context, Exception ex)
+    private static async Task WriteProblemAsync(HttpContext context, int status, string title, string detail)
     {
-        if (context.Response.HasStarted)
-        {
-            throw ex;
-        }
+        if (context.Response.HasStarted) return;
 
         context.Response.Clear();
-        context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
-        context.Response.ContentType = "application/json";
+        context.Response.StatusCode = status;
+        context.Response.ContentType = "application/problem+json";
 
-        var problem = new
+        var problem = new ProblemDetails
         {
-            type = "https://tools.ietf.org/html/rfc9110#section-15.6.1",
-            title = "Serverfehler",
-            status = context.Response.StatusCode,
-            detail = ex.Message,
-            traceId = context.TraceIdentifier
+            Type = $"https://tools.ietf.org/html/rfc9110#section-{(status == 400 ? "15.5.1" : "15.6.1")}",
+            Title = title,
+            Status = status,
+            Detail = detail,
+            Extensions = { ["traceId"] = context.TraceIdentifier }
         };
 
-        await context.Response.WriteAsync(JsonSerializer.Serialize(problem));
+        await context.Response.WriteAsJsonAsync(problem);
     }
 }

DbFirst.API/Program.cs

@@ -1,18 +1,11 @@
-using DbFirst.API.Middleware;
 using DbFirst.API.Dashboards;
 using DbFirst.API.Hubs;
+using DbFirst.API.Middleware;
 using DbFirst.Application;
-using DbFirst.Application.Repositories;
-using DbFirst.Domain;
-using DbFirst.Domain.Entities;
 using DbFirst.Infrastructure;
-using DbFirst.Infrastructure.Repositories;
 using DevExpress.AspNetCore;
 using DevExpress.DashboardAspNetCore;
-using DevExpress.DashboardCommon;
 using DevExpress.DashboardWeb;
-using DevExpress.DataAccess.Json;
-using System.Xml.Linq;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -20,6 +13,7 @@ var builder = WebApplication.CreateBuilder(args);
 builder.Services.AddControllers();
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen();
+builder.Services.AddProblemDetails();
 
 // TODO: allow listed origins configured in appsettings.json
 // In any case, dont let them to free to use without cors. if there is no origin specified, block all.
@@ -36,7 +30,7 @@ builder.Services.AddCors(options =>
         }
         else
         {
-            var origins = builder.Configuration.GetSection("Cors:AllowedOrigins").Get<string[]>() ?? Array.Empty<string>();
+            var origins = builder.Configuration.GetSection("Cors:AllowedOrigins").Get<string[]>() ?? [];
             if (origins.Length > 0)
             {
                 policy.WithOrigins(origins)
@@ -51,98 +45,11 @@ builder.Services.AddCors(options =>
 builder.Services.AddInfrastructure(builder.Configuration);
 builder.Services.AddApplication();
 
-builder.Services.AddScoped<ICatalogRepository, CatalogRepository>();
-builder.Services.AddScoped<IMassDataRepository, MassDataRepository>();
-builder.Services.AddScoped<ILayoutRepository, LayoutRepository>();
-
 builder.Services.AddDevExpressControls();
 builder.Services.AddSignalR();
 builder.Services.AddSingleton<IDashboardChangeNotifier, DashboardChangeNotifier>();
-builder.Services.AddScoped<DashboardConfigurator>((IServiceProvider serviceProvider) => {
-    var dashboardsPath = Path.Combine(builder.Environment.ContentRootPath, "Data", "Dashboards");
-    Directory.CreateDirectory(dashboardsPath);
-
-    var defaultDashboardPath = Path.Combine(dashboardsPath, "DefaultDashboard.xml");
-    if (!File.Exists(defaultDashboardPath))
-    {
-        var defaultDashboard = new Dashboard();
-        defaultDashboard.Title.Text = "Default Dashboard";
-        defaultDashboard.SaveToXml(defaultDashboardPath);
-    }
-
-    var dashboardBaseUrl = builder.Configuration["Dashboard:BaseUrl"]
-        ?? builder.Configuration["ApiBaseUrl"]
-        ?? builder.Configuration["ASPNETCORE_URLS"]?.Split(';', StringSplitOptions.RemoveEmptyEntries).FirstOrDefault()
-        ?? "https://localhost:7204";
-
-    dashboardBaseUrl = dashboardBaseUrl.TrimEnd('/');
-
-    var catalogsGridDashboardPath = Path.Combine(dashboardsPath, "CatalogsGrid.xml");
-    if (!File.Exists(catalogsGridDashboardPath))
-    {
-        var dashboard = new Dashboard();
-        dashboard.Title.Text = "Catalogs (Dashboard Grid)";
-
-        var catalogDataSource = new DashboardJsonDataSource("Catalogs (API)")
-        {
-            ComponentName = "catalogsDataSource",
-            JsonSource = new UriJsonSource(new Uri($"{dashboardBaseUrl}/api/catalogs"))
-        };
-
-        dashboard.DataSources.Add(catalogDataSource);
-
-        var grid = new GridDashboardItem
-        {
-            DataSource = catalogDataSource,
-            Name = "Catalogs"
-        };
-
-        grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.Guid))) { Name = "Id" });
-        grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.CatTitle))) { Name = "Titel" });
-        grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.CatString))) { Name = "String" });
-        grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.AddedWho))) { Name = "Angelegt von" });
-        grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.AddedWhen))) { Name = "Angelegt am" });
-        grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.ChangedWho))) { Name = "Geändert von" });
-        grid.Columns.Add(new GridDimensionColumn(new Dimension(nameof(VwmyCatalog.ChangedWhen))) { Name = "Geändert am" });
-
-        dashboard.Items.Add(grid);
-
-        var layoutGroup = new DashboardLayoutGroup { Orientation = DashboardLayoutGroupOrientation.Vertical };
-        layoutGroup.ChildNodes.Add(new DashboardLayoutItem(grid));
-        dashboard.LayoutRoot = layoutGroup;
-
-        dashboard.SaveToXml(catalogsGridDashboardPath);
-    }
-
-    DashboardConfigurator configurator = new DashboardConfigurator();
-
-    var connectionString = builder.Configuration.GetConnectionString("DefaultConnection") ?? string.Empty;
-    var notifier = serviceProvider.GetRequiredService<IDashboardChangeNotifier>();
-    var dashboardStorage = new SqlDashboardStorage(connectionString, "TBDD_SMF_CONFIG", notifier: notifier);
-    configurator.SetDashboardStorage(dashboardStorage);
-
-    DataSourceInMemoryStorage dataSourceStorage = new DataSourceInMemoryStorage();
-    DashboardJsonDataSource jsonDataSourceUrl = new DashboardJsonDataSource("JSON Data Source (URL)");
-    jsonDataSourceUrl.JsonSource = new UriJsonSource(
-            new Uri("https://raw.githubusercontent.com/DevExpress-Examples/DataSources/master/JSON/customers.json"));
-    jsonDataSourceUrl.RootElement = "Customers";
-    dataSourceStorage.RegisterDataSource("jsonDataSourceUrl", jsonDataSourceUrl.SaveToXml());
-
-    var catalogsJsonDataSource = new DashboardJsonDataSource("Catalogs (API)")
-    {
-        ComponentName = "catalogsDataSource",
-        JsonSource = new UriJsonSource(new Uri($"{dashboardBaseUrl}/api/catalogs"))
-    };
-    dataSourceStorage.RegisterDataSource(catalogsJsonDataSource.ComponentName, catalogsJsonDataSource.SaveToXml());
-    dataSourceStorage.RegisterDataSource(catalogsJsonDataSource.Name, catalogsJsonDataSource.SaveToXml());
-
-    configurator.SetDataSourceStorage(dataSourceStorage);
-
-    EnsureDashboardInStorage(dashboardStorage, "DefaultDashboard", defaultDashboardPath);
-    EnsureDashboardInStorage(dashboardStorage, "CatalogsGrid", catalogsGridDashboardPath);
-
-    return configurator;
-});
+builder.Services.AddScoped<DashboardConfigurator>(sp =>
+    DashboardConfiguratorFactory.Create(sp, builder.Configuration, builder.Environment));
 
 var app = builder.Build();
 
@@ -164,16 +71,4 @@ app.MapDashboardRoute("api/dashboard", "DefaultDashboard");
 app.MapHub<DashboardsHub>("/hubs/dashboards");
 app.MapControllers();
 
-app.Run();
-
-static void EnsureDashboardInStorage(IEditableDashboardStorage storage, string id, string filePath)
-{
-    var exists = storage.GetAvailableDashboardsInfo().Any(info => string.Equals(info.ID, id, StringComparison.OrdinalIgnoreCase));
-    if (exists || !File.Exists(filePath))
-    {
-        return;
-    }
-
-    var doc = XDocument.Load(filePath);
-    storage.AddDashboard(doc, id);
-}
+app.Run();

DbFirst.Application/Catalogs/CatalogReadDto.cs

@@ -3,9 +3,9 @@ namespace DbFirst.Application.Catalogs;
 public class CatalogReadDto
 {
     public int Guid { get; set; }
-    public string CatTitle { get; set; } = null!;
-    public string CatString { get; set; } = null!;
-    public string AddedWho { get; set; } = null!;
+    public string CatTitle { get; set; } = string.Empty;
+    public string CatString { get; set; } = string.Empty;
+    public string AddedWho { get; set; } = string.Empty;
     public DateTime AddedWhen { get; set; }
     public string? ChangedWho { get; set; }
     public DateTime? ChangedWhen { get; set; }

DbFirst.Application/Catalogs/CatalogWriteDto.cs

@@ -4,7 +4,7 @@ namespace DbFirst.Application.Catalogs;
 
 public class CatalogWriteDto
 {
-    public string CatTitle { get; set; } = null!;
-    public string CatString { get; set; } = null!;
+    public string CatTitle { get; set; } = string.Empty;
+    public string CatString { get; set; } = string.Empty;
     public CatalogUpdateProcedure UpdateProcedure { get; set; } = CatalogUpdateProcedure.Update;
 }

DbFirst.Application/Catalogs/Commands/UpdateCatalogHandler.cs

@@ -25,18 +25,20 @@ public class UpdateCatalogHandler : IRequestHandler<UpdateCatalogCommand, Catalo
             return null;
         }
 
+        if (request.Dto.UpdateProcedure == CatalogUpdateProcedure.Update &&
+            !string.Equals(existing.CatTitle, request.Dto.CatTitle, StringComparison.OrdinalIgnoreCase))
+        {
+            throw new InvalidOperationException("Titel kann nicht geändert werden.");
+        }
+
         var entity = _mapper.Map<VwmyCatalog>(request.Dto);
         entity.Guid = request.Id;
-        entity.CatTitle = request.Dto.UpdateProcedure == CatalogUpdateProcedure.Update
-            ? existing.CatTitle
-            : request.Dto.CatTitle;
         entity.AddedWho = existing.AddedWho;
         entity.AddedWhen = existing.AddedWhen;
         entity.ChangedWho = "system";
         entity.ChangedWhen = DateTime.UtcNow;
 
-        var procedure = request.Dto.UpdateProcedure;
-        var updated = await _repository.UpdateAsync(request.Id, entity, procedure, cancellationToken);
+        var updated = await _repository.UpdateAsync(request.Id, entity, request.Dto.UpdateProcedure, cancellationToken);
         return updated == null ? null : _mapper.Map<CatalogReadDto>(updated);
     }
 }

DbFirst.Application/DbFirst.Application.csproj

@@ -9,8 +9,8 @@
   <ItemGroup>
     <PackageReference Include="AutoMapper" Version="12.0.1" />
     <PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="12.0.1" />
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="8.0.2" />
-    <PackageReference Include="MediatR.Extensions.Microsoft.DependencyInjection" Version="11.1.0" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="10.0.0" />
+	<PackageReference Include="MediatR" Version="14.1.0" />
   </ItemGroup>
 
   <ItemGroup>

DbFirst.Application/DependencyInjection.cs

@@ -8,7 +8,8 @@ public static class DependencyInjection
     public static IServiceCollection AddApplication(this IServiceCollection services)
     {
         services.AddAutoMapper(typeof(DependencyInjection).Assembly);
-        services.AddMediatR(typeof(DependencyInjection).Assembly);
+        services.AddMediatR(cfg =>
+    cfg.RegisterServicesFromAssembly(typeof(DependencyInjection).Assembly));
         return services;
     }
 }

DbFirst.Application/Layouts/LayoutDto.cs

@@ -0,0 +1,9 @@
+namespace DbFirst.Application.Layouts;
+
+public class LayoutDto
+{
+    public string LayoutType { get; set; } = string.Empty;
+    public string LayoutKey { get; set; } = string.Empty;
+    public string UserName { get; set; } = string.Empty;
+    public string LayoutData { get; set; } = string.Empty;
+}

DbFirst.BlazorWebApp/AppSettings.cs

@@ -0,0 +1,6 @@
+namespace DbFirst.BlazorWebApp;
+
+public class AppSettings
+{
+    public string ApiBaseUrl { get; set; } = string.Empty;
+}

DbFirst.BlazorWebApp/Components/App.razor

@@ -5,10 +5,7 @@
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <base href="/" />
-    @DxResourceManager.RegisterTheme(Themes.Fluent.Clone(properties =>
-    {
-        properties.ApplyToPageElements = true;
-    }))
+    @DxResourceManager.RegisterTheme(Themes.Fluent)
     @DxResourceManager.RegisterScripts()
 
     <link href="_content/DevExpress.Blazor.Dashboard/ace.css" rel="stylesheet" />
@@ -21,6 +18,7 @@
     <link href="_content/DevExpress.Blazor.Dashboard/dx-dashboard.light.min.css" rel="stylesheet" />
 
     <link rel="stylesheet" href="bootstrap/bootstrap.min.css" />
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap-icons@1.11.3/font/bootstrap-icons.min.css" />
 
     <link rel="stylesheet" href="app.css" />
     <link rel="stylesheet" href="DbFirst.BlazorWebApp.styles.css" />

DbFirst.BlazorWebApp/Components/BandEditor.razor

@@ -0,0 +1,55 @@
+<div class="band-editor">
+    <button class="band-editor-toggle" @onclick="() => IsExpanded = !IsExpanded">
+        <span class="band-editor-toggle-icon @(IsExpanded ? "expanded" : "")">&#9658;</span>
+        <span>Layout</span>
+    </button>
+    @if (IsExpanded)
+    {
+        <div class="band-editor-body">
+            <div class="band-controls">
+                <DxButton Text="Band hinzufügen" Click="OnAddBand" />
+                <DxButton Text="Layout speichern" Click="OnSaveLayout" Enabled="@CanSave" />
+                <DxButton Text="Layout zurücksetzen" Click="OnResetLayout" />
+            </div>
+            @foreach (var band in Bands)
+            {
+                <div class="band-row">
+                    <DxTextBox Text="@band.Caption" TextChanged="@(value => OnBandCaptionChanged.InvokeAsync((band, value)))" />
+                    <DxButton Text="Entfernen" Click="@(() => OnRemoveBand.InvokeAsync(band))" />
+                </div>
+            }
+            <DxFormLayout CssClass="band-columns" ColCount="2">
+                @foreach (var column in Columns)
+                {
+                    <DxFormLayoutItem Caption="@column.Caption">
+                        <DxComboBox Data="@BandOptions"
+                                    TData="BandOption"
+                                    TValue="string"
+                                    TextFieldName="Caption"
+                                    ValueFieldName="Id"
+                                    Value="@GetColumnBand(column.FieldName)"
+                                    ValueChanged="@(value => OnColumnBandChanged.InvokeAsync((column.FieldName, value)))"
+                                    Width="100%" />
+                    </DxFormLayoutItem>
+                }
+            </DxFormLayout>
+        </div>
+    }
+</div>
+
+@code {
+    private bool IsExpanded { get; set; }
+
+    [Parameter, EditorRequired] public List<BandDefinition> Bands { get; set; } = new();
+    [Parameter, EditorRequired] public List<BandOption> BandOptions { get; set; } = new();
+    [Parameter, EditorRequired] public List<ColumnDefinition> Columns { get; set; } = new();
+    [Parameter, EditorRequired] public Func<string, string> GetColumnBand { get; set; } = _ => string.Empty;
+    [Parameter, EditorRequired] public bool CanSave { get; set; }
+
+    [Parameter] public EventCallback OnAddBand { get; set; }
+    [Parameter] public EventCallback OnSaveLayout { get; set; }
+    [Parameter] public EventCallback OnResetLayout { get; set; }
+    [Parameter] public EventCallback<BandDefinition> OnRemoveBand { get; set; }
+    [Parameter] public EventCallback<(BandDefinition Band, string Value)> OnBandCaptionChanged { get; set; }
+    [Parameter] public EventCallback<(string FieldName, string? BandId)> OnColumnBandChanged { get; set; }
+}

DbFirst.BlazorWebApp/Components/BandGridBase.cs

@@ -0,0 +1,278 @@
+using DbFirst.BlazorWebApp.Models.Grid;
+using DbFirst.BlazorWebApp.Services;
+using DevExpress.Blazor;
+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Components.Forms;
+using Microsoft.AspNetCore.Components.Rendering;
+
+namespace DbFirst.BlazorWebApp.Components;
+
+public abstract class BandGridBase<TItem> : ComponentBase
+{
+    [Inject] protected BandLayoutService BandLayoutService { get; set; } = default!;
+
+    // --- Abstract: jedes Grid definiert diese selbst ---
+    protected abstract string LayoutKey { get; }
+    protected abstract List<ColumnDefinition> ColumnDefinitions { get; }
+
+    // --- Band-Layout Felder ---
+    protected BandLayout bandLayout = new();
+    protected Dictionary<string, string> columnBandAssignments = new();
+    protected List<BandOption> bandOptions = new();
+    protected Dictionary<string, ColumnDefinition> columnLookup = new();
+    protected string? layoutUser;
+    protected bool gridLayoutApplied;
+    protected IGrid? gridRef;
+
+    // --- SizeMode ---
+    protected SizeMode _sizeMode = SizeMode.Medium;
+    protected static readonly List<SizeMode> _sizeModes = Enum.GetValues<SizeMode>().ToList();
+
+    protected string? errorMessage;
+    protected string? infoMessage;
+    protected bool isLoading;
+    protected bool hasLoaded;
+    protected EditContext? editContext;
+    protected ValidationMessageStore? validationMessageStore;
+    protected string popupHeaderText = "Edit";
+    protected int _focusedVisibleIndex;
+
+    private const string LayoutType = "GRID_BANDS";
+
+    // --- Lifecycle ---
+    protected async Task InitializeBandLayoutAsync()
+    {
+        columnLookup = ColumnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
+        layoutUser = await BandLayoutService.EnsureLayoutUserAsync();
+        bandLayout = await BandLayoutService.LoadBandLayoutAsync(LayoutType, LayoutKey, layoutUser, columnLookup);
+        columnBandAssignments = BandLayoutService.BuildAssignmentsFromLayout(bandLayout);
+        ApplyColumnLayoutFromStorage();
+        _sizeMode = bandLayout.SizeMode;
+        UpdateBandOptions();
+    }
+
+    protected async Task ApplyGridLayoutAfterRenderAsync()
+    {
+        if (!gridLayoutApplied && gridRef != null && bandLayout.GridLayout != null)
+        {
+            gridRef.LoadLayout(bandLayout.GridLayout);
+            gridLayoutApplied = true;
+            await InvokeAsync(StateHasChanged);
+        }
+    }
+
+    // --- Layout speichern / zurücksetzen ---
+    protected async Task SaveLayoutAsync()
+    {
+        if (string.IsNullOrWhiteSpace(layoutUser)) return;
+        CaptureColumnLayoutFromGrid();
+        await BandLayoutService.SaveBandLayoutAsync(LayoutType, LayoutKey, layoutUser, bandLayout);
+    }
+
+    protected async Task ResetLayoutAsync()
+    {
+        if (string.IsNullOrWhiteSpace(layoutUser)) return;
+        await BandLayoutService.ResetBandLayoutAsync(LayoutType, LayoutKey, layoutUser);
+        bandLayout = new BandLayout();
+        columnBandAssignments.Clear();
+        UpdateBandOptions();
+        foreach (var column in ColumnDefinitions)
+            column.Width = null;
+        columnLookup = ColumnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
+        _sizeMode = SizeMode.Medium;
+        gridRef?.LoadLayout(new GridPersistentLayout());
+        gridLayoutApplied = false;
+    }
+
+    private void CaptureColumnLayoutFromGrid()
+    {
+        if (gridRef == null) return;
+        var layout = gridRef.SaveLayout();
+        bandLayout.GridLayout = layout;
+        bandLayout.SizeMode = _sizeMode;
+        var orderedColumns = layout.Columns
+            .Where(c => !string.IsNullOrWhiteSpace(c.FieldName))
+            .OrderBy(c => c.VisibleIndex)
+            .ToList();
+        bandLayout.ColumnOrder = orderedColumns.Select(c => c.FieldName).ToList();
+        bandLayout.ColumnWidths = orderedColumns
+            .Where(c => !string.IsNullOrWhiteSpace(c.Width))
+            .ToDictionary(c => c.FieldName, c => c.Width, StringComparer.OrdinalIgnoreCase);
+    }
+
+    private void ApplyColumnLayoutFromStorage()
+    {
+        foreach (var column in ColumnDefinitions)
+        {
+            if (bandLayout.ColumnWidths.TryGetValue(column.FieldName, out var width) && !string.IsNullOrWhiteSpace(width))
+                column.Width = width;
+        }
+        columnLookup = ColumnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
+    }
+
+    // --- Band-Methoden ---
+    protected bool CanSaveBandLayout => !string.IsNullOrWhiteSpace(layoutUser);
+
+    protected virtual bool ShowCommandColumn => true;
+
+    protected void AddBand()
+    {
+        bandLayout.Bands.Add(new BandDefinition { Id = Guid.NewGuid().ToString("N"), Caption = "Band" });
+        UpdateBandOptions();
+    }
+
+    protected void RemoveBand(BandDefinition band)
+    {
+        bandLayout.Bands.Remove(band);
+        foreach (var key in columnBandAssignments.Where(p => p.Value == band.Id).Select(p => p.Key).ToList())
+            columnBandAssignments.Remove(key);
+        UpdateBandOptions();
+        SyncBandsFromAssignments();
+    }
+
+    protected void UpdateBandCaption(BandDefinition band, string value)
+    {
+        band.Caption = value;
+        UpdateBandOptions();
+    }
+
+    protected void UpdateColumnBand(string fieldName, string? bandId)
+    {
+        if (string.IsNullOrWhiteSpace(bandId))
+            columnBandAssignments.Remove(fieldName);
+        else
+            columnBandAssignments[fieldName] = bandId;
+        SyncBandsFromAssignments();
+    }
+
+    protected string GetColumnBand(string fieldName)
+        => columnBandAssignments.TryGetValue(fieldName, out var bandId) ? bandId : string.Empty;
+
+    protected void SyncBandsFromAssignments()
+    {
+        foreach (var band in bandLayout.Bands)
+        {
+            band.Columns = ColumnDefinitions
+                .Where(c => columnBandAssignments.TryGetValue(c.FieldName, out var id) && id == band.Id)
+                .Select(c => c.FieldName)
+                .ToList();
+        }
+        _ = InvokeAsync(StateHasChanged);
+    }
+
+    protected void UpdateBandOptions()
+    {
+        bandOptions = [new() { Id = string.Empty, Caption = "Ohne Band" }];
+        bandOptions.AddRange(bandLayout.Bands.Select(b => new BandOption { Id = b.Id, Caption = b.Caption }));
+    }
+
+    // --- SizeMode ---
+    protected string FormatSizeText(SizeMode size) => size switch
+    {
+        SizeMode.Small => "Klein",
+        SizeMode.Medium => "Mittel",
+        SizeMode.Large => "Groß",
+        _ => size.ToString()
+    };
+
+    protected void OnSizeChange(DropDownButtonItemClickEventArgs args)
+    {
+        _sizeMode = Enum.Parse<SizeMode>(args.ItemInfo.Id);
+    }
+
+    // --- RenderColumns / BuildDataColumn ---
+    protected RenderFragment RenderColumns() => builder =>
+    {
+        var seq = 0;
+        if (ShowCommandColumn)
+        {
+            builder.OpenComponent<DxGridCommandColumn>(seq++);
+            builder.AddAttribute(seq++, "Width", "120px");
+            builder.CloseComponent();
+        }
+
+        var grouped = bandLayout.Bands.SelectMany(b => b.Columns).ToHashSet(StringComparer.OrdinalIgnoreCase);
+        foreach (var column in ColumnDefinitions.Where(c => !grouped.Contains(c.FieldName)))
+            BuildDataColumn(builder, ref seq, column);
+
+        foreach (var band in bandLayout.Bands)
+        {
+            if (band.Columns.Count == 0) continue;
+            builder.OpenComponent<DxGridBandColumn>(seq++);
+            builder.AddAttribute(seq++, "Caption", band.Caption);
+            builder.AddAttribute(seq++, "Columns", (RenderFragment)(bandBuilder =>
+            {
+                var bandSeq = 0;
+                foreach (var columnName in band.Columns)
+                {
+                    if (columnLookup.TryGetValue(columnName, out var column))
+                        BuildDataColumn(bandBuilder, ref bandSeq, column);
+                }
+            }));
+            builder.CloseComponent();
+        }
+    };
+
+    protected void BuildDataColumn(RenderTreeBuilder builder, ref int seq, ColumnDefinition column)
+    {
+        builder.OpenComponent<DxGridDataColumn>(seq++);
+        builder.AddAttribute(seq++, "FieldName", column.FieldName);
+        builder.AddAttribute(seq++, "Caption", column.Caption);
+        if (!string.IsNullOrWhiteSpace(column.Width))
+            builder.AddAttribute(seq++, "Width", column.Width);
+        if (!string.IsNullOrWhiteSpace(column.DisplayFormat))
+            builder.AddAttribute(seq++, "DisplayFormat", column.DisplayFormat);
+        if (column.ReadOnly)
+            builder.AddAttribute(seq++, "ReadOnly", true);
+        builder.CloseComponent();
+    }
+
+    protected void SetEditContext(EditContext context)
+    {
+        if (editContext == context) return;
+        if (editContext != null)
+            editContext.OnFieldChanged -= OnEditFieldChanged;
+        editContext = context;
+        validationMessageStore = new ValidationMessageStore(editContext);
+        editContext.OnFieldChanged += OnEditFieldChanged;
+    }
+
+    protected virtual void OnEditFieldChanged(object? sender, FieldChangedEventArgs e)
+    {
+        validationMessageStore?.Clear();
+        editContext?.NotifyValidationStateChanged();
+    }
+
+    protected void SetPopupHeaderText(bool isNew) => popupHeaderText = isNew ? "Neu" : "Edit";
+
+    protected async Task EditFocusedRow()
+        => await gridRef!.StartEditRowAsync(_focusedVisibleIndex);
+
+    protected Task DeleteFocusedRow()
+    {
+        gridRef!.ShowRowDeleteConfirmation(_focusedVisibleIndex);
+        return Task.CompletedTask;
+    }
+
+    protected async Task SaveLayoutWithFeedbackAsync()
+    {
+        try
+        {
+            await SaveLayoutAsync();
+            infoMessage = "Layout gespeichert.";
+            errorMessage = null;
+        }
+        catch (Exception ex)
+        {
+            errorMessage = $"Layout konnte nicht gespeichert werden: {ex.Message}";
+        }
+    }
+
+    protected async Task ResetLayoutWithFeedbackAsync()
+    {
+        await ResetLayoutAsync();
+        infoMessage = "Layout zurückgesetzt.";
+        errorMessage = null;
+    }
+
+}

DbFirst.BlazorWebApp/Components/CatalogsGrid.razor

@@ -1,5 +1,5 @@
-@inject CatalogApiClient Api
-@inject BandLayoutService BandLayoutService
+@inherits BandGridBase<CatalogReadDto>
+@inject ICatalogApiClient Api
 
 @if (!string.IsNullOrWhiteSpace(errorMessage))
 {
@@ -24,47 +24,21 @@ else if (items.Count == 0)
 }
 else
 {
-    <div class="band-editor">
-        <button class="band-editor-toggle" @onclick="() => bandEditorExpanded = !bandEditorExpanded">
-            <span class="band-editor-toggle-icon @(bandEditorExpanded ? "expanded" : "")">&#9658;</span>
-            <span>Layout</span>
-        </button>
-        @if (bandEditorExpanded)
-        {
-            <div class="band-editor-body">
-                <div class="band-controls">
-                    <DxButton Text="Band hinzufügen" Click="AddBand" />
-                    <DxButton Text="Layout speichern" Click="SaveLayoutAsync" Enabled="@CanSaveBandLayout" />
-                    <DxButton Text="Layout zurücksetzen" Click="ResetLayoutAsync" />
-                </div>
-                @foreach (var band in bandLayout.Bands)
-                {
-                    <div class="band-row">
-                        <DxTextBox Text="@band.Caption" TextChanged="@(value => UpdateBandCaption(band, value))" />
-                        <DxButton Text="Entfernen" Click="@(() => RemoveBand(band))" />
-                    </div>
-                }
-                <DxFormLayout CssClass="band-columns" ColCount="2">
-                    @foreach (var column in columnDefinitions)
-                    {
-                        <DxFormLayoutItem Caption="@column.Caption">
-                            <DxComboBox Data="@bandOptions"
-                                        TData="BandOption"
-                                        TValue="string"
-                                        TextFieldName="Caption"
-                                        ValueFieldName="Id"
-                                        Value="@GetColumnBand(column.FieldName)"
-                                        ValueChanged="@(value => UpdateColumnBand(column.FieldName, value))"
-                                        Width="100%" />
-                        </DxFormLayoutItem>
-                    }
-                </DxFormLayout>
-            </div>
-        }
-    </div>
+    <BandEditor Bands="@bandLayout.Bands"
+                BandOptions="@bandOptions"
+                Columns="@ColumnDefinitions"
+                GetColumnBand="GetColumnBand"
+                CanSave="@CanSaveBandLayout"
+                OnAddBand="AddBand"
+                OnSaveLayout="SaveLayoutWithFeedbackAsync"
+                OnResetLayout="ResetLayoutWithFeedbackAsync"
+                OnRemoveBand="RemoveBand"
+                OnBandCaptionChanged="@(args => UpdateBandCaption(args.Band, args.Value))"
+                OnColumnBandChanged="@(args => UpdateColumnBand(args.FieldName, args.BandId))" />
 
     <div class="grid-section">
         <DxGrid Data="@items"
+                ColumnChooserButtonDisplayMode="GridColumnChooserButtonDisplayMode.Always"
                 TItem="CatalogReadDto"
                 KeyFieldName="@nameof(CatalogReadDto.Guid)"
                 SizeMode="@_sizeMode"
@@ -85,9 +59,42 @@ else
                 DataItemDeleting="OnDataItemDeleting"
                 FocusedRowEnabled="true"
                 @bind-FocusedRowKey="focusedRowKey"
+                RowClick="@(args => _focusedVisibleIndex = args.VisibleIndex)"
                 @ref="gridRef">
             <ToolbarTemplate>
                 <DxToolbar>
+                    <DxToolbarItem Alignment="ToolbarItemAlignment.Left">
+                        <Template Context="_">
+                            <DxButton IconCssClass="bi bi-plus-lg"
+                                      RenderStyle="ButtonRenderStyle.Secondary"
+                                      RenderStyleMode="ButtonRenderStyleMode.Text"
+                                      Click="@(() => gridRef!.StartEditNewRowAsync())" />
+                        </Template>
+                    </DxToolbarItem>
+                    <DxToolbarItem Alignment="ToolbarItemAlignment.Left">
+                        <Template Context="_">
+                            <DxButton IconCssClass="bi bi-pencil"
+                                      RenderStyle="ButtonRenderStyle.Secondary"
+                                      RenderStyleMode="ButtonRenderStyleMode.Text"
+                                      Click="EditFocusedRow" />
+                        </Template>
+                    </DxToolbarItem>
+                    <DxToolbarItem Alignment="ToolbarItemAlignment.Left">
+                        <Template Context="_">
+                            <DxButton IconCssClass="bi bi-trash"
+                                      RenderStyle="ButtonRenderStyle.Secondary"
+                                      RenderStyleMode="ButtonRenderStyleMode.Text"
+                                      Click="DeleteFocusedRow" />
+                        </Template>
+                    </DxToolbarItem>
+                    <DxToolbarItem Alignment="ToolbarItemAlignment.Right">
+                        <Template Context="_">
+                            <DxButton Text="Spalten"
+                                      RenderStyle="ButtonRenderStyle.Secondary"
+                                      RenderStyleMode="ButtonRenderStyleMode.Text"
+                                      Click="@(() => gridRef!.ShowColumnChooser())" />
+                        </Template>
+                    </DxToolbarItem>
                     <DxToolbarItem Alignment="ToolbarItemAlignment.Right">
                         <Template Context="_">
                             <DxDropDownButton Text="@FormatSizeText(_sizeMode)"
@@ -142,35 +149,21 @@ else
 
 @code {
     private List<CatalogReadDto> items = new();
-    private bool isLoading;
-    private bool hasLoaded;
-    private string? errorMessage;
-    private string? infoMessage;
-    private EditContext? editContext;
-    private ValidationMessageStore? validationMessageStore;
-    private IGrid? gridRef;
     private int? focusedRowKey;
-    private string popupHeaderText = "Edit";
-    private const string LayoutType = "GRID_BANDS";
-    private const string LayoutKey = "CatalogsGrid";
-    private string? layoutUser;
-    private BandLayout bandLayout = new();
-    private Dictionary<string, string> columnBandAssignments = new();
-    private List<BandOption> bandOptions = new();
-    private Dictionary<string, ColumnDefinition> columnLookup = new();
-    private bool gridLayoutApplied;
-    private bool bandEditorExpanded;
 
-    private List<ColumnDefinition> columnDefinitions = new()
-    {
-        new() { FieldName = nameof(CatalogReadDto.Guid), Caption = "Id", Width = "140px", FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(CatalogReadDto.CatTitle), Caption = "Titel", FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(CatalogReadDto.CatString), Caption = "String", FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(CatalogReadDto.AddedWho), Caption = "Angelegt von", ReadOnly = true, FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(CatalogReadDto.AddedWhen), Caption = "Angelegt am", ReadOnly = true, FilterType = ColumnFilterType.Date },
-        new() { FieldName = nameof(CatalogReadDto.ChangedWho), Caption = "Geändert von", ReadOnly = true, FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(CatalogReadDto.ChangedWhen), Caption = "Geändert am", ReadOnly = true, FilterType = ColumnFilterType.Date }
-    };
+    protected override string LayoutKey => "CatalogsGrid";
+    protected override bool ShowCommandColumn => false;
+
+    protected override List<ColumnDefinition> ColumnDefinitions { get; } = new()
+{
+    new() { FieldName = nameof(CatalogReadDto.Guid),       Caption = "Id",          Width = "140px", FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(CatalogReadDto.CatTitle),   Caption = "Titel",                        FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(CatalogReadDto.CatString),  Caption = "String",                       FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(CatalogReadDto.AddedWho),   Caption = "Angelegt von", ReadOnly = true, FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(CatalogReadDto.AddedWhen),  Caption = "Angelegt am",  ReadOnly = true, FilterType = ColumnFilterType.Date },
+    new() { FieldName = nameof(CatalogReadDto.ChangedWho), Caption = "Geändert von", ReadOnly = true, FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(CatalogReadDto.ChangedWhen),Caption = "Geändert am",  ReadOnly = true, FilterType = ColumnFilterType.Date }
+};
 
     private readonly List<ProcedureOption> procedureOptions = new()
     {
@@ -178,44 +171,15 @@ else
         new() { Value = 1, Text = "PRTBMY_CATALOG_SAVE" }
     };
 
-    private bool CanSaveBandLayout => !string.IsNullOrWhiteSpace(layoutUser);
-
-    private SizeMode _sizeMode = SizeMode.Medium;
-    private static readonly List<SizeMode> _sizeModes = Enum.GetValues<SizeMode>().ToList();
-
-    private string FormatSizeText(SizeMode size) => size switch
-    {
-        SizeMode.Small => "Klein",
-        SizeMode.Medium => "Mittel",
-        SizeMode.Large => "Groß",
-        _ => size.ToString()
-    };
-
-    private void OnSizeChange(DropDownButtonItemClickEventArgs args)
-    {
-        _sizeMode = Enum.Parse<SizeMode>(args.ItemInfo.Id);
-    }
-
     protected override async Task OnInitializedAsync()
     {
-        columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-        layoutUser = await BandLayoutService.EnsureLayoutUserAsync();
-        bandLayout = await BandLayoutService.LoadBandLayoutAsync(LayoutType, LayoutKey, layoutUser, columnLookup);
-        columnBandAssignments = BandLayoutService.BuildAssignmentsFromLayout(bandLayout);
-        ApplyColumnLayoutFromStorage();
-        _sizeMode = bandLayout.SizeMode;
-        UpdateBandOptions();
+        await InitializeBandLayoutAsync();
         await LoadCatalogs();
     }
 
     protected override async Task OnAfterRenderAsync(bool firstRender)
     {
-        if (!gridLayoutApplied && gridRef != null && bandLayout.GridLayout != null)
-        {
-            gridRef.LoadLayout(bandLayout.GridLayout);
-            gridLayoutApplied = true;
-            await InvokeAsync(StateHasChanged);
-        }
+        await ApplyGridLayoutAfterRenderAsync();
     }
 
     private async Task LoadCatalogs()
@@ -238,185 +202,7 @@ else
         }
     }
 
-    private async Task SaveLayoutAsync()
-    {
-        if (string.IsNullOrWhiteSpace(layoutUser))
-            return;
-
-        try
-        {
-            CaptureColumnLayoutFromGrid();
-            await BandLayoutService.SaveBandLayoutAsync(LayoutType, LayoutKey, layoutUser, bandLayout);
-            infoMessage = "Layout gespeichert.";
-            errorMessage = null;
-        }
-        catch (Exception ex)
-        {
-            errorMessage = $"Layout konnte nicht gespeichert werden: {ex.Message}";
-        }
-    }
-
-    private async Task ResetLayoutAsync()
-    {
-        if (string.IsNullOrWhiteSpace(layoutUser))
-            return;
-
-        await BandLayoutService.ResetBandLayoutAsync(LayoutType, LayoutKey, layoutUser);
-
-        bandLayout = new BandLayout();
-        columnBandAssignments.Clear();
-        UpdateBandOptions();
-
-        foreach (var column in columnDefinitions)
-            column.Width = null;
-        columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-
-        _sizeMode = SizeMode.Medium;
-
-        if (gridRef != null)
-            gridRef.LoadLayout(new GridPersistentLayout());
-        gridLayoutApplied = false;
-
-        infoMessage = "Layout zurückgesetzt.";
-        errorMessage = null;
-    }
-
-    private void CaptureColumnLayoutFromGrid()
-    {
-        if (gridRef == null)
-            return;
-
-        var layout = gridRef.SaveLayout();
-        bandLayout.GridLayout = layout;
-        bandLayout.SizeMode = _sizeMode;
-
-        var orderedColumns = layout.Columns
-            .Where(c => !string.IsNullOrWhiteSpace(c.FieldName))
-            .OrderBy(c => c.VisibleIndex)
-            .ToList();
-
-        bandLayout.ColumnOrder = orderedColumns.Select(c => c.FieldName).ToList();
-        bandLayout.ColumnWidths = orderedColumns
-            .Where(c => !string.IsNullOrWhiteSpace(c.Width))
-            .ToDictionary(c => c.FieldName, c => c.Width, StringComparer.OrdinalIgnoreCase);
-    }
-
-    private void ApplyColumnLayoutFromStorage()
-    {
-        foreach (var column in columnDefinitions)
-        {
-            if (bandLayout.ColumnWidths.TryGetValue(column.FieldName, out var width) && !string.IsNullOrWhiteSpace(width))
-                column.Width = width;
-        }
-        columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-    }
-
-    private void AddBand()
-    {
-        bandLayout.Bands.Add(new BandDefinition { Id = Guid.NewGuid().ToString("N"), Caption = "Band" });
-        UpdateBandOptions();
-    }
-
-    private void RemoveBand(BandDefinition band)
-    {
-        bandLayout.Bands.Remove(band);
-        foreach (var key in columnBandAssignments.Where(p => p.Value == band.Id).Select(p => p.Key).ToList())
-            columnBandAssignments.Remove(key);
-        UpdateBandOptions();
-        SyncBandsFromAssignments();
-    }
-
-    private void UpdateBandCaption(BandDefinition band, string value)
-    {
-        band.Caption = value;
-        UpdateBandOptions();
-    }
-
-    private void UpdateColumnBand(string fieldName, string? bandId)
-    {
-        if (string.IsNullOrWhiteSpace(bandId))
-            columnBandAssignments.Remove(fieldName);
-        else
-            columnBandAssignments[fieldName] = bandId;
-        SyncBandsFromAssignments();
-    }
-
-    private string GetColumnBand(string fieldName)
-        => columnBandAssignments.TryGetValue(fieldName, out var bandId) ? bandId : string.Empty;
-
-    private void SyncBandsFromAssignments()
-    {
-        foreach (var band in bandLayout.Bands)
-        {
-            band.Columns = columnDefinitions
-                .Where(c => columnBandAssignments.TryGetValue(c.FieldName, out var id) && id == band.Id)
-                .Select(c => c.FieldName)
-                .ToList();
-        }
-        StateHasChanged();
-    }
-
-    private void UpdateBandOptions()
-    {
-        bandOptions = new List<BandOption> { new() { Id = string.Empty, Caption = "Ohne Band" } };
-        bandOptions.AddRange(bandLayout.Bands.Select(b => new BandOption { Id = b.Id, Caption = b.Caption }));
-    }
-
-    private RenderFragment RenderColumns() => builder =>
-    {
-        var seq = 0;
-        builder.OpenComponent<DxGridCommandColumn>(seq++);
-        builder.AddAttribute(seq++, "Width", "120px");
-        builder.CloseComponent();
-
-        var grouped = bandLayout.Bands.SelectMany(b => b.Columns).ToHashSet(StringComparer.OrdinalIgnoreCase);
-        foreach (var column in columnDefinitions.Where(c => !grouped.Contains(c.FieldName)))
-            BuildDataColumn(builder, ref seq, column);
-
-        foreach (var band in bandLayout.Bands)
-        {
-            if (band.Columns.Count == 0) continue;
-
-            builder.OpenComponent<DxGridBandColumn>(seq++);
-            builder.AddAttribute(seq++, "Caption", band.Caption);
-            builder.AddAttribute(seq++, "Columns", (RenderFragment)(bandBuilder =>
-            {
-                var bandSeq = 0;
-                foreach (var columnName in band.Columns)
-                {
-                    if (columnLookup.TryGetValue(columnName, out var column))
-                        BuildDataColumn(bandBuilder, ref bandSeq, column);
-                }
-            }));
-            builder.CloseComponent();
-        }
-    };
-
-    private void BuildDataColumn(RenderTreeBuilder builder, ref int seq, ColumnDefinition column)
-    {
-        builder.OpenComponent<DxGridDataColumn>(seq++);
-        builder.AddAttribute(seq++, "FieldName", column.FieldName);
-        builder.AddAttribute(seq++, "Caption", column.Caption);
-        if (!string.IsNullOrWhiteSpace(column.Width))
-            builder.AddAttribute(seq++, "Width", column.Width);
-        if (!string.IsNullOrWhiteSpace(column.DisplayFormat))
-            builder.AddAttribute(seq++, "DisplayFormat", column.DisplayFormat);
-        if (column.ReadOnly)
-            builder.AddAttribute(seq++, "ReadOnly", true);
-        builder.CloseComponent();
-    }
-
-    private void SetEditContext(EditContext context)
-    {
-        if (editContext == context) return;
-        if (editContext != null)
-            editContext.OnFieldChanged -= OnEditFieldChanged;
-        editContext = context;
-        validationMessageStore = new ValidationMessageStore(editContext);
-        editContext.OnFieldChanged += OnEditFieldChanged;
-    }
-
-    private void OnEditFieldChanged(object? sender, FieldChangedEventArgs e)
+    protected override void OnEditFieldChanged(object? sender, FieldChangedEventArgs e)
     {
         if (validationMessageStore == null || editContext == null) return;
 
@@ -434,8 +220,6 @@ else
         }
     }
 
-    private void SetPopupHeaderText(bool isNew) => popupHeaderText = isNew ? "Neu" : "Edit";
-
     private void OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
     {
         popupHeaderText = e.IsNew ? "Neu" : "Edit";

DbFirst.BlazorWebApp/Components/MassDataGrid.razor

@@ -1,5 +1,5 @@
-@inject MassDataApiClient Api
-@inject BandLayoutService BandLayoutService
+@inherits BandGridBase<MassDataReadDto>
+@inject IMassDataApiClient Api
 
 @if (!string.IsNullOrWhiteSpace(errorMessage))
 {
@@ -25,44 +25,17 @@ else if (items.Count == 0)
 else
 {
     
-    <div class="band-editor">
-        <button class="band-editor-toggle" @onclick="() => bandEditorExpanded = !bandEditorExpanded">
-            <span class="band-editor-toggle-icon @(bandEditorExpanded ? "expanded" : "")">&#9658;</span>
-            <span>Layout</span>
-        </button>
-        @if (bandEditorExpanded)
-        {
-            <div class="band-editor-body">
-                <div class="band-controls">
-                    <DxButton Text="Band hinzufügen" Click="AddBand" />
-                    <DxButton Text="Layout speichern" Click="SaveLayoutAsync" Enabled="@CanSaveBandLayout" />
-                    <DxButton Text="Layout zurücksetzen" Click="ResetLayoutAsync" />
-                </div>
-                @foreach (var band in bandLayout.Bands)
-                {
-                    <div class="band-row">
-                        <DxTextBox Text="@band.Caption" TextChanged="@(value => UpdateBandCaption(band, value))" />
-                        <DxButton Text="Entfernen" Click="@(() => RemoveBand(band))" />
-                    </div>
-                }
-                <DxFormLayout CssClass="band-columns" ColCount="2">
-                    @foreach (var column in columnDefinitions)
-                    {
-                        <DxFormLayoutItem Caption="@column.Caption">
-                            <DxComboBox Data="@bandOptions"
-                                        TData="BandOption"
-                                        TValue="string"
-                                        TextFieldName="Caption"
-                                        ValueFieldName="Id"
-                                        Value="@GetColumnBand(column.FieldName)"
-                                        ValueChanged="@(value => UpdateColumnBand(column.FieldName, value))"
-                                        Width="100%" />
-                        </DxFormLayoutItem>
-                    }
-                </DxFormLayout>
-            </div>
-        }
-    </div>
+    <BandEditor Bands="@bandLayout.Bands"
+                BandOptions="@bandOptions"
+                Columns="@ColumnDefinitions"
+                GetColumnBand="GetColumnBand"
+                CanSave="@CanSaveBandLayout"
+                OnAddBand="AddBand"
+                OnSaveLayout="SaveLayoutWithFeedbackAsync"
+                OnResetLayout="ResetLayoutWithFeedbackAsync"
+                OnRemoveBand="RemoveBand"
+                OnBandCaptionChanged="@(args => UpdateBandCaption(args.Band, args.Value))"
+                OnColumnBandChanged="@(args => UpdateColumnBand(args.FieldName, args.BandId))" />
 
     <div class="mb-3 page-size-selector">
         <span class="page-size-label">Datensätze je Seite:</span>
@@ -78,6 +51,7 @@ else
 
     <div class="grid-section">
         <DxGrid Data="@items"
+                ColumnChooserButtonDisplayMode="GridColumnChooserButtonDisplayMode.Always"
                 TItem="MassDataReadDto"
                 KeyFieldName="@nameof(MassDataReadDto.Id)"
                 SizeMode="@_sizeMode"
@@ -98,9 +72,42 @@ else
                 DataItemDeleting="OnDataItemDeleting"
                 FocusedRowEnabled="true"
                 @bind-FocusedRowKey="focusedRowKey"
+                RowClick="@(args => _focusedVisibleIndex = args.VisibleIndex)"
                 @ref="gridRef">
             <ToolbarTemplate>
                 <DxToolbar>
+                    <DxToolbarItem Alignment="ToolbarItemAlignment.Left">
+                        <Template Context="_">
+                            <DxButton IconCssClass="bi bi-plus-lg"
+                                      RenderStyle="ButtonRenderStyle.Secondary"
+                                      RenderStyleMode="ButtonRenderStyleMode.Text"
+                                      Click="@(() => gridRef!.StartEditNewRowAsync())" />
+                        </Template>
+                    </DxToolbarItem>
+                    <DxToolbarItem Alignment="ToolbarItemAlignment.Left">
+                        <Template Context="_">
+                            <DxButton IconCssClass="bi bi-pencil"
+                                      RenderStyle="ButtonRenderStyle.Secondary"
+                                      RenderStyleMode="ButtonRenderStyleMode.Text"
+                                      Click="EditFocusedRow" />
+                        </Template>
+                    </DxToolbarItem>
+                    <DxToolbarItem Alignment="ToolbarItemAlignment.Left">
+                        <Template Context="_">
+                            <DxButton IconCssClass="bi bi-trash"
+                                      RenderStyle="ButtonRenderStyle.Secondary"
+                                      RenderStyleMode="ButtonRenderStyleMode.Text"
+                                      Click="DeleteFocusedRow" />
+                        </Template>
+                    </DxToolbarItem>
+                    <DxToolbarItem Alignment="ToolbarItemAlignment.Right">
+                        <Template Context="_">
+                            <DxButton Text="Spalten"
+                                      RenderStyle="ButtonRenderStyle.Secondary"
+                                      RenderStyleMode="ButtonRenderStyleMode.Text"
+                                      Click="@(() => gridRef!.ShowColumnChooser())" />
+                        </Template>
+                    </DxToolbarItem>
                     <DxToolbarItem Alignment="ToolbarItemAlignment.Right">
                         <Template Context="_">
                             <DxDropDownButton Text="@FormatSizeText(_sizeMode)"
@@ -168,38 +175,24 @@ else
 
 @code {
     private List<MassDataReadDto> items = new();
-    private bool isLoading;
-    private bool hasLoaded;
-    private string? errorMessage;
-    private string? infoMessage;
     private int pageIndex;
     private int pageCount = 1;
     private int? pageSize = 100;
-    private string popupHeaderText = "Edit";
-    private EditContext? editContext;
-    private ValidationMessageStore? validationMessageStore;
-    private IGrid? gridRef;
     private int? focusedRowKey;
-    private const string LayoutType = "GRID_BANDS";
-    private const string LayoutKey = "MassDataGrid";
-    private string? layoutUser;
-    private BandLayout bandLayout = new();
-    private Dictionary<string, string> columnBandAssignments = new();
-    private List<BandOption> bandOptions = new();
-    private Dictionary<string, ColumnDefinition> columnLookup = new();
-    private bool gridLayoutApplied;
-    private bool bandEditorExpanded;
 
-    private List<ColumnDefinition> columnDefinitions = new()
-    {
-        new() { FieldName = nameof(MassDataReadDto.Id), Caption = "Id", Width = "90px", ReadOnly = true, FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(MassDataReadDto.CustomerName), Caption = "CustomerName", FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(MassDataReadDto.Amount), Caption = "Amount", DisplayFormat = "c2", FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(MassDataReadDto.Category), Caption = "Category", ReadOnly = true, FilterType = ColumnFilterType.Text },
-        new() { FieldName = nameof(MassDataReadDto.StatusFlag), Caption = "Status", ReadOnly = true, FilterType = ColumnFilterType.Bool },
-        new() { FieldName = nameof(MassDataReadDto.AddedWhen), Caption = "Added", ReadOnly = true, FilterType = ColumnFilterType.Date },
-        new() { FieldName = nameof(MassDataReadDto.ChangedWhen), Caption = "Changed", ReadOnly = true, FilterType = ColumnFilterType.Date }
-    };
+    protected override string LayoutKey => "MassDataGrid";
+    protected override bool ShowCommandColumn => false;
+
+    protected override List<ColumnDefinition> ColumnDefinitions { get; } = new()
+{
+    new() { FieldName = nameof(MassDataReadDto.Id),           Caption = "Id",           Width = "90px", ReadOnly = true, FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(MassDataReadDto.CustomerName), Caption = "CustomerName",                 FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(MassDataReadDto.Amount),       Caption = "Amount",       DisplayFormat = "c2", FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(MassDataReadDto.Category),     Caption = "Category",     ReadOnly = true, FilterType = ColumnFilterType.Text },
+    new() { FieldName = nameof(MassDataReadDto.StatusFlag),   Caption = "Status",       ReadOnly = true, FilterType = ColumnFilterType.Bool },
+    new() { FieldName = nameof(MassDataReadDto.AddedWhen),    Caption = "Added",        ReadOnly = true, FilterType = ColumnFilterType.Date },
+    new() { FieldName = nameof(MassDataReadDto.ChangedWhen),  Caption = "Changed",      ReadOnly = true, FilterType = ColumnFilterType.Date }
+};
 
     private readonly List<PageSizeOption> pageSizeOptions = new()
     {
@@ -215,44 +208,15 @@ else
         new() { Value = 0, Text = "PRMassdata_UpsertByCustomerName" }
     };
 
-    private bool CanSaveBandLayout => !string.IsNullOrWhiteSpace(layoutUser);
-
-    private SizeMode _sizeMode = SizeMode.Medium;
-    private static readonly List<SizeMode> _sizeModes = Enum.GetValues<SizeMode>().ToList();
-
-    private string FormatSizeText(SizeMode size) => size switch
-    {
-        SizeMode.Small => "Klein",
-        SizeMode.Medium => "Mittel",
-        SizeMode.Large => "Groß",
-        _ => size.ToString()
-    };
-
-    private void OnSizeChange(DropDownButtonItemClickEventArgs args)
-    {
-        _sizeMode = Enum.Parse<SizeMode>(args.ItemInfo.Id);
-    }
-
     protected override async Task OnInitializedAsync()
     {
-        columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-        layoutUser = await BandLayoutService.EnsureLayoutUserAsync();
-        bandLayout = await BandLayoutService.LoadBandLayoutAsync(LayoutType, LayoutKey, layoutUser, columnLookup);
-        columnBandAssignments = BandLayoutService.BuildAssignmentsFromLayout(bandLayout);
-        ApplyColumnLayoutFromStorage();
-        _sizeMode = bandLayout.SizeMode;
-        UpdateBandOptions();
+        await InitializeBandLayoutAsync();
         await LoadPage(0);
     }
 
     protected override async Task OnAfterRenderAsync(bool firstRender)
     {
-        if (!gridLayoutApplied && gridRef != null && bandLayout.GridLayout != null)
-        {
-            gridRef.LoadLayout(bandLayout.GridLayout);
-            gridLayoutApplied = true;
-            await InvokeAsync(StateHasChanged);
-        }
+        await ApplyGridLayoutAfterRenderAsync();
     }
 
     private async Task LoadPage(int page)
@@ -288,171 +252,7 @@ else
         await LoadPage(0);
     }
 
-    private async Task SaveLayoutAsync()
-    {
-        if (string.IsNullOrWhiteSpace(layoutUser))
-            return;
-        try
-        {
-            CaptureColumnLayoutFromGrid();
-            await BandLayoutService.SaveBandLayoutAsync(LayoutType, LayoutKey, layoutUser, bandLayout);
-            infoMessage = "Layout gespeichert.";
-            errorMessage = null;
-        }
-        catch (Exception ex)
-        {
-            errorMessage = $"Layout konnte nicht gespeichert werden: {ex.Message}";
-        }
-    }
-
-    private async Task ResetLayoutAsync()
-    {
-        if (string.IsNullOrWhiteSpace(layoutUser))
-            return;
-        await BandLayoutService.ResetBandLayoutAsync(LayoutType, LayoutKey, layoutUser);
-        bandLayout = new BandLayout();
-        columnBandAssignments.Clear();
-        UpdateBandOptions();
-        foreach (var column in columnDefinitions)
-            column.Width = null;
-        columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-        _sizeMode = SizeMode.Medium;
-        if (gridRef != null)
-            gridRef.LoadLayout(new GridPersistentLayout());
-        gridLayoutApplied = false;
-        infoMessage = "Layout zurückgesetzt.";
-        errorMessage = null;
-    }
-
-    private void CaptureColumnLayoutFromGrid()
-    {
-        if (gridRef == null) return;
-        var layout = gridRef.SaveLayout();
-        bandLayout.GridLayout = layout;
-        bandLayout.SizeMode = _sizeMode;
-        var orderedColumns = layout.Columns
-            .Where(c => !string.IsNullOrWhiteSpace(c.FieldName))
-            .OrderBy(c => c.VisibleIndex)
-            .ToList();
-        bandLayout.ColumnOrder = orderedColumns.Select(c => c.FieldName).ToList();
-        bandLayout.ColumnWidths = orderedColumns
-            .Where(c => !string.IsNullOrWhiteSpace(c.Width))
-            .ToDictionary(c => c.FieldName, c => c.Width, StringComparer.OrdinalIgnoreCase);
-    }
-
-    private void ApplyColumnLayoutFromStorage()
-    {
-        foreach (var column in columnDefinitions)
-        {
-            if (bandLayout.ColumnWidths.TryGetValue(column.FieldName, out var width) && !string.IsNullOrWhiteSpace(width))
-                column.Width = width;
-        }
-        columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-    }
-
-    private void AddBand()
-    {
-        bandLayout.Bands.Add(new BandDefinition { Id = Guid.NewGuid().ToString("N"), Caption = "Band" });
-        UpdateBandOptions();
-    }
-
-    private void RemoveBand(BandDefinition band)
-    {
-        bandLayout.Bands.Remove(band);
-        foreach (var key in columnBandAssignments.Where(p => p.Value == band.Id).Select(p => p.Key).ToList())
-            columnBandAssignments.Remove(key);
-        UpdateBandOptions();
-        SyncBandsFromAssignments();
-    }
-
-    private void UpdateBandCaption(BandDefinition band, string value)
-    {
-        band.Caption = value;
-        UpdateBandOptions();
-    }
-
-    private void UpdateColumnBand(string fieldName, string? bandId)
-    {
-        if (string.IsNullOrWhiteSpace(bandId))
-            columnBandAssignments.Remove(fieldName);
-        else
-            columnBandAssignments[fieldName] = bandId;
-        SyncBandsFromAssignments();
-    }
-
-    private string GetColumnBand(string fieldName)
-        => columnBandAssignments.TryGetValue(fieldName, out var bandId) ? bandId : string.Empty;
-
-    private void SyncBandsFromAssignments()
-    {
-        foreach (var band in bandLayout.Bands)
-        {
-            band.Columns = columnDefinitions
-                .Where(c => columnBandAssignments.TryGetValue(c.FieldName, out var id) && id == band.Id)
-                .Select(c => c.FieldName)
-                .ToList();
-        }
-        StateHasChanged();
-    }
-
-    private void UpdateBandOptions()
-    {
-        bandOptions = new List<BandOption> { new() { Id = string.Empty, Caption = "Ohne Band" } };
-        bandOptions.AddRange(bandLayout.Bands.Select(b => new BandOption { Id = b.Id, Caption = b.Caption }));
-    }
-
-    private RenderFragment RenderColumns() => builder =>
-    {
-        var seq = 0;
-        builder.OpenComponent<DxGridCommandColumn>(seq++);
-        builder.AddAttribute(seq++, "Width", "120px");
-        builder.CloseComponent();
-        var grouped = bandLayout.Bands.SelectMany(b => b.Columns).ToHashSet(StringComparer.OrdinalIgnoreCase);
-        foreach (var column in columnDefinitions.Where(c => !grouped.Contains(c.FieldName)))
-            BuildDataColumn(builder, ref seq, column);
-        foreach (var band in bandLayout.Bands)
-        {
-            if (band.Columns.Count == 0) continue;
-            builder.OpenComponent<DxGridBandColumn>(seq++);
-            builder.AddAttribute(seq++, "Caption", band.Caption);
-            builder.AddAttribute(seq++, "Columns", (RenderFragment)(bandBuilder =>
-            {
-                var bandSeq = 0;
-                foreach (var columnName in band.Columns)
-                {
-                    if (columnLookup.TryGetValue(columnName, out var column))
-                        BuildDataColumn(bandBuilder, ref bandSeq, column);
-                }
-            }));
-            builder.CloseComponent();
-        }
-    };
-
-    private void BuildDataColumn(RenderTreeBuilder builder, ref int seq, ColumnDefinition column)
-    {
-        builder.OpenComponent<DxGridDataColumn>(seq++);
-        builder.AddAttribute(seq++, "FieldName", column.FieldName);
-        builder.AddAttribute(seq++, "Caption", column.Caption);
-        if (!string.IsNullOrWhiteSpace(column.Width))
-            builder.AddAttribute(seq++, "Width", column.Width);
-        if (!string.IsNullOrWhiteSpace(column.DisplayFormat))
-            builder.AddAttribute(seq++, "DisplayFormat", column.DisplayFormat);
-        if (column.ReadOnly)
-            builder.AddAttribute(seq++, "ReadOnly", true);
-        builder.CloseComponent();
-    }
-
-    private void SetEditContext(EditContext context)
-    {
-        if (editContext == context) return;
-        if (editContext != null)
-            editContext.OnFieldChanged -= OnEditFieldChanged;
-        editContext = context;
-        validationMessageStore = new ValidationMessageStore(editContext);
-        editContext.OnFieldChanged += OnEditFieldChanged;
-    }
-
-    private void OnEditFieldChanged(object? sender, FieldChangedEventArgs e)
+    protected override void OnEditFieldChanged(object? sender, FieldChangedEventArgs e)
     {
         if (validationMessageStore == null || editContext == null) return;
         if (e.FieldIdentifier.FieldName == nameof(MassDataEditModel.UpdateProcedure))
@@ -468,9 +268,7 @@ else
         }
     }
 
-    private void SetPopupHeaderText(bool isNew) => popupHeaderText = isNew ? "Neu" : "Edit";
-
-    private async Task OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
+    private void OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
     {
         if (e.IsNew)
         {
@@ -523,18 +321,17 @@ else
             Category = editModel.Category,
             StatusFlag = editModel.StatusFlag
         };
-        try
+
+        var result = await Api.UpsertAsync(dto);
+        if (!result.Success)
         {
-            var saved = await Api.UpsertAsync(dto);
-            infoMessage = editModel.IsNew ? "MassData angelegt." : "MassData aktualisiert.";
-            focusedRowKey = saved.Id;
-            await LoadPage(pageIndex);
-        }
-        catch (Exception ex)
-        {
-            errorMessage = $"Fehler beim Speichern: {ex.Message}";
+            errorMessage = result.Error ?? "Speichern fehlgeschlagen.";
             e.Cancel = true;
+            return;
         }
+        infoMessage = editModel.IsNew ? "MassData angelegt." : "MassData aktualisiert.";
+        focusedRowKey = result.Value?.Id;
+        await LoadPage(pageIndex);
     }
 
     private void AddValidationError(MassDataEditModel editModel, string fieldName, string message)

DbFirst.BlazorWebApp/Components/Pages/Dashboard.razor

@@ -1,9 +1,9 @@
 @page "/dashboard"
 @page "/dashboards/{DashboardId?}"
 @implements IAsyncDisposable
-@inject Microsoft.Extensions.Configuration.IConfiguration Configuration
+@inject IOptions<AppSettings> AppSettingsOptions
 @inject NavigationManager Navigation
-@inject DashboardApiClient DashboardApi
+@inject IDashboardApiClient DashboardApi
 
 <PageTitle>Dashboards</PageTitle>
 
@@ -45,12 +45,17 @@
     private string SelectedDashboardId { get; set; } = string.Empty;
     private string DashboardKey => $"{SelectedDashboardId}-{(IsDesigner ? "designer" : "viewer")}";
 
-    private string DashboardEndpoint => $"{Configuration["ApiBaseUrl"]?.TrimEnd('/')}/api/dashboard";
-    private string HubEndpoint => $"{Configuration["ApiBaseUrl"]?.TrimEnd('/')}/hubs/dashboards";
+    private string DashboardEndpoint => $"{AppSettingsOptions.Value.ApiBaseUrl.TrimEnd('/')}/api/dashboard";
+    private string HubEndpoint => $"{AppSettingsOptions.Value.ApiBaseUrl.TrimEnd('/')}/hubs/dashboards";
 
     protected override async Task OnInitializedAsync()
     {
         await RefreshDashboards();
+    }
+
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (!firstRender) return;
 
         _hubConnection = new HubConnectionBuilder()
             .WithUrl(HubEndpoint)
@@ -67,11 +72,6 @@
 
     protected override async Task OnParametersSetAsync()
     {
-        if (dashboards.Count == 0)
-        {
-            await RefreshDashboards();
-        }
-
         var requestedId = string.IsNullOrWhiteSpace(DashboardId) || string.Equals(DashboardId, "default", StringComparison.OrdinalIgnoreCase)
             ? null
             : DashboardId;

DbFirst.BlazorWebApp/Components/Pages/Home.razor

@@ -31,8 +31,8 @@
 
     public class CarouselData
     {
-        public string Source { get; set; }
-        public string AlternateText { get; set; }
+        public string Source { get; set; } = string.Empty;
+        public string AlternateText { get; set; } = string.Empty;
 
         public CarouselData(string source, string alt)
         {

DbFirst.BlazorWebApp/Components/_Imports.razor

@@ -17,4 +17,5 @@
 @using DevExpress.Blazor
 @using DevExpress.DashboardBlazor
 @using DevExpress.DashboardWeb
-@using DevExpress.Data.Filtering
+@using DevExpress.Data.Filtering
+@using Microsoft.Extensions.Options

DbFirst.BlazorWebApp/Models/ApiResult.cs

@@ -0,0 +1,7 @@
+namespace DbFirst.BlazorWebApp.Models;
+
+public record ApiResult<T>(bool Success, T? Value, string? Error)
+{
+    public static ApiResult<T> Ok(T? value) => new(true, value, null);
+    public static ApiResult<T> Fail(string? error) => new(false, default, error);
+}

DbFirst.BlazorWebApp/Models/CatalogReadDto.cs

@@ -3,9 +3,9 @@ namespace DbFirst.BlazorWebApp.Models;
 public class CatalogReadDto
 {
     public int Guid { get; set; }
-    public string CatTitle { get; set; } = null!;
-    public string CatString { get; set; } = null!;
-    public string AddedWho { get; set; } = null!;
+    public string CatTitle { get; set; } = string.Empty;
+    public string CatString { get; set; } = string.Empty;
+    public string AddedWho { get; set; } = string.Empty;
     public DateTime AddedWhen { get; set; }
     public string? ChangedWho { get; set; }
     public DateTime? ChangedWhen { get; set; }

DbFirst.BlazorWebApp/Models/Grid/BandLayoutModels.cs

@@ -4,8 +4,8 @@ namespace DbFirst.BlazorWebApp.Models.Grid
 {
     public class BandLayout
     {
-        public List<BandDefinition> Bands { get; set; } = new();
-        public List<string> ColumnOrder { get; set; } = new();
+        public List<BandDefinition> Bands { get; set; } = [];
+        public List<string> ColumnOrder { get; set; } = [];
         public Dictionary<string, string?> ColumnWidths { get; set; } = new(StringComparer.OrdinalIgnoreCase);
         public GridPersistentLayout? GridLayout { get; set; }
         public SizeMode SizeMode { get; set; } = SizeMode.Medium;
@@ -15,7 +15,7 @@ namespace DbFirst.BlazorWebApp.Models.Grid
     {
         public string Id { get; set; } = string.Empty;
         public string Caption { get; set; } = string.Empty;
-        public List<string> Columns { get; set; } = new();
+        public List<string> Columns { get; set; } = [];
     }
 
     public class BandOption

DbFirst.BlazorWebApp/Program.cs

@@ -1,3 +1,4 @@
+using DbFirst.BlazorWebApp;
 using DbFirst.BlazorWebApp.Components;
 using DbFirst.BlazorWebApp.Services;
 using DevExpress.Blazor;
@@ -13,33 +14,18 @@ builder.Services.AddScoped<ThemeState>();
 builder.Services.AddScoped<BandLayoutService>();
 
 var apiBaseUrl = builder.Configuration["ApiBaseUrl"];
-if (!string.IsNullOrWhiteSpace(apiBaseUrl))
+builder.Services.Configure<AppSettings>(builder.Configuration);
+void ConfigureClient(HttpClient client)
 {
-    builder.Services.AddHttpClient<CatalogApiClient>(client =>
-    {
+    if (!string.IsNullOrWhiteSpace(apiBaseUrl))
         client.BaseAddress = new Uri(apiBaseUrl);
-    });
-    builder.Services.AddHttpClient<DashboardApiClient>(client =>
-    {
-        client.BaseAddress = new Uri(apiBaseUrl);
-    });
-    builder.Services.AddHttpClient<MassDataApiClient>(client =>
-    {
-        client.BaseAddress = new Uri(apiBaseUrl);
-    });
-    builder.Services.AddHttpClient<LayoutApiClient>(client =>
-    {
-        client.BaseAddress = new Uri(apiBaseUrl);
-    });
-}
-else
-{
-    builder.Services.AddHttpClient<CatalogApiClient>();
-    builder.Services.AddHttpClient<DashboardApiClient>();
-    builder.Services.AddHttpClient<MassDataApiClient>();
-    builder.Services.AddHttpClient<LayoutApiClient>();
 }
 
+builder.Services.AddHttpClient<ICatalogApiClient, CatalogApiClient>(ConfigureClient);
+builder.Services.AddHttpClient<IDashboardApiClient, DashboardApiClient>(ConfigureClient);
+builder.Services.AddHttpClient<IMassDataApiClient, MassDataApiClient>(ConfigureClient);
+builder.Services.AddHttpClient<ILayoutApiClient, LayoutApiClient>(ConfigureClient);
+
 var app = builder.Build();
 
 // Configure the HTTP request pipeline.

DbFirst.BlazorWebApp/Services/ApiClientHelper.cs

@@ -0,0 +1,59 @@
+using System.Net;
+
+namespace DbFirst.BlazorWebApp.Services;
+
+internal sealed class ProblemDetailsDto
+{
+    public string? Type { get; set; }
+    public string? Title { get; set; }
+    public string? Detail { get; set; }
+}
+
+internal static class ApiClientHelper
+{
+    public static async Task<string> ReadErrorAsync(HttpResponseMessage response)
+    {
+        string? problemTitle = null;
+        string? problemDetail = null;
+
+        try
+        {
+            var problem = await response.Content.ReadFromJsonAsync<ProblemDetailsDto>();
+            if (problem != null)
+            {
+                problemTitle = problem.Title;
+                problemDetail = problem.Detail ?? problem.Type;
+            }
+        }
+        catch { }
+
+        var status = response.StatusCode;
+        var reason = response.ReasonPhrase;
+        var body = await response.Content.ReadAsStringAsync();
+
+        string? detail = problemDetail;
+        if (string.IsNullOrWhiteSpace(detail) && !string.IsNullOrWhiteSpace(body))
+            detail = body;
+
+        return status switch
+        {
+            HttpStatusCode.BadRequest => $"Eingabe ungültig{FormatSuffix(problemTitle, detail, reason)}",
+            HttpStatusCode.NotFound => $"Nicht gefunden{FormatSuffix(problemTitle, detail, reason)}",
+            HttpStatusCode.Conflict => $"Konflikt{FormatSuffix(problemTitle, detail, reason)}",
+            HttpStatusCode.Unauthorized => $"Nicht autorisiert{FormatSuffix(problemTitle, detail, reason)}",
+            HttpStatusCode.Forbidden => $"Nicht erlaubt{FormatSuffix(problemTitle, detail, reason)}",
+            HttpStatusCode.InternalServerError => $"Serverfehler{FormatSuffix(problemTitle, detail, reason)}",
+            _ => $"Fehler {(int)status} {reason ?? string.Empty}{FormatSuffix(problemTitle, detail, reason)}"
+        };
+    }
+
+    private static string FormatSuffix(string? title, string? detail, string? reason)
+    {
+        var parts = new List<string>();
+        if (!string.IsNullOrWhiteSpace(title)) parts.Add(title);
+        if (!string.IsNullOrWhiteSpace(detail)) parts.Add(detail);
+        if (parts.Count == 0 && !string.IsNullOrWhiteSpace(reason)) parts.Add(reason);
+        if (parts.Count == 0) return string.Empty;
+        return ": " + string.Join(" | ", parts);
+    }
+}

DbFirst.BlazorWebApp/Services/BandLayoutService.cs

@@ -5,20 +5,26 @@ using System.Text.Json;
 
 namespace DbFirst.BlazorWebApp.Services
 {
-    public class BandLayoutService(LayoutApiClient layoutApi, IJSRuntime jsRuntime)
+    public class BandLayoutService(ILayoutApiClient layoutApi, IJSRuntime jsRuntime)
     {
         private const string LayoutUserStorageKey = "layoutUser";
         private readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
+        private string? _cachedLayoutUser;
 
         public async Task<string> EnsureLayoutUserAsync()
         {
+            if (!string.IsNullOrWhiteSpace(_cachedLayoutUser))
+                return _cachedLayoutUser;
+
             var layoutUser = await jsRuntime.InvokeAsync<string?>("localStorage.getItem", LayoutUserStorageKey);
             if (string.IsNullOrWhiteSpace(layoutUser))
             {
                 layoutUser = Guid.NewGuid().ToString("N");
                 await jsRuntime.InvokeVoidAsync("localStorage.setItem", LayoutUserStorageKey, layoutUser);
             }
-            return layoutUser;
+
+            _cachedLayoutUser = layoutUser;
+            return _cachedLayoutUser;
         }
 
         public async Task<BandLayout> LoadBandLayoutAsync(
@@ -82,9 +88,9 @@ namespace DbFirst.BlazorWebApp.Services
             Dictionary<string, ColumnDefinition> columnLookup)
         {
             layout ??= new BandLayout();
-            layout.Bands ??= new List<BandDefinition>();
-            layout.ColumnOrder ??= new List<string>();
-            layout.ColumnWidths ??= new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase);
+            layout.Bands ??= [];
+            layout.ColumnOrder ??= [];
+            layout.ColumnWidths ??= [];
 
             foreach (var band in layout.Bands)
             {

DbFirst.BlazorWebApp/Services/CatalogApiClient.cs

@@ -1,10 +1,8 @@
-using System.Net;
-using System.Net.Http.Json;
 using DbFirst.BlazorWebApp.Models;
 
 namespace DbFirst.BlazorWebApp.Services;
 
-public class CatalogApiClient
+public class CatalogApiClient : ICatalogApiClient
 {
     private readonly HttpClient _httpClient;
     private const string Endpoint = "api/catalogs";
@@ -14,123 +12,51 @@ public class CatalogApiClient
         _httpClient = httpClient;
     }
 
-    public async Task<List<CatalogReadDto>> GetAllAsync()
+    public async Task<List<CatalogReadDto>> GetAllAsync(CancellationToken ct = default)
     {
-        var result = await _httpClient.GetFromJsonAsync<List<CatalogReadDto>>(Endpoint);
-        return result ?? new List<CatalogReadDto>();
+        var result = await _httpClient.GetFromJsonAsync<List<CatalogReadDto>>(Endpoint, ct);
+        return result ?? [];
     }
 
-    public async Task<CatalogReadDto?> GetByIdAsync(int id)
+    public async Task<CatalogReadDto?> GetByIdAsync(int id, CancellationToken ct = default)
     {
-        return await _httpClient.GetFromJsonAsync<CatalogReadDto>($"{Endpoint}/{id}");
+        return await _httpClient.GetFromJsonAsync<CatalogReadDto>($"{Endpoint}/{id}", ct);
     }
 
-    public async Task<ApiResult<CatalogReadDto?>> CreateAsync(CatalogWriteDto dto)
+    public async Task<ApiResult<CatalogReadDto?>> CreateAsync(CatalogWriteDto dto, CancellationToken ct = default)
     {
-        var response = await _httpClient.PostAsJsonAsync(Endpoint, dto);
+        var response = await _httpClient.PostAsJsonAsync(Endpoint, dto, ct);
         if (response.IsSuccessStatusCode)
         {
             var payload = await response.Content.ReadFromJsonAsync<CatalogReadDto>();
             return ApiResult<CatalogReadDto?>.Ok(payload);
         }
 
-        var error = await ReadErrorAsync(response);
+        var error = await ApiClientHelper.ReadErrorAsync(response);
         return ApiResult<CatalogReadDto?>.Fail(error);
     }
 
-    public async Task<ApiResult<bool>> UpdateAsync(int id, CatalogWriteDto dto)
+    public async Task<ApiResult<bool>> UpdateAsync(int id, CatalogWriteDto dto, CancellationToken ct = default)
     {
-        var response = await _httpClient.PutAsJsonAsync($"{Endpoint}/{id}", dto);
+        var response = await _httpClient.PutAsJsonAsync($"{Endpoint}/{id}", dto, ct);
         if (response.IsSuccessStatusCode)
         {
             return ApiResult<bool>.Ok(true);
         }
 
-        var error = await ReadErrorAsync(response);
+        var error = await ApiClientHelper.ReadErrorAsync(response);
         return ApiResult<bool>.Fail(error);
     }
 
-    public async Task<ApiResult<bool>> DeleteAsync(int id)
+    public async Task<ApiResult<bool>> DeleteAsync(int id, CancellationToken ct = default)
     {
-        var response = await _httpClient.DeleteAsync($"{Endpoint}/{id}");
+        var response = await _httpClient.DeleteAsync($"{Endpoint}/{id}", ct);
         if (response.IsSuccessStatusCode)
         {
             return ApiResult<bool>.Ok(true);
         }
 
-        var error = await ReadErrorAsync(response);
+        var error = await ApiClientHelper.ReadErrorAsync(response);
         return ApiResult<bool>.Fail(error);
     }
-
-    private static async Task<string> ReadErrorAsync(HttpResponseMessage response)
-    {
-        string? problemTitle = null;
-        string? problemDetail = null;
-
-        try
-        {
-            var problem = await response.Content.ReadFromJsonAsync<ProblemDetailsDto>();
-            if (problem != null)
-            {
-                problemTitle = problem.Title;
-                problemDetail = problem.Detail ?? problem.Type;
-            }
-        }
-        catch
-        {
-        }
-
-        var status = response.StatusCode;
-        var reason = response.ReasonPhrase;
-        var body = await response.Content.ReadAsStringAsync();
-
-        string? detail = problemDetail;
-        if (string.IsNullOrWhiteSpace(detail) && !string.IsNullOrWhiteSpace(body))
-        {
-            detail = body;
-        }
-
-        if (status == HttpStatusCode.Conflict)
-        {
-            return "Datensatz existiert bereits. Bitte wählen Sie einen anderen Titel.";
-        }
-        if (status == HttpStatusCode.BadRequest && (detail?.Contains("CatTitle cannot be changed", StringComparison.OrdinalIgnoreCase) ?? false))
-        {
-            return "Titel kann nicht geändert werden.";
-        }
-
-        return status switch
-        {
-            HttpStatusCode.BadRequest => $"Eingabe ungültig{FormatSuffix(problemTitle, detail, reason)}",
-            HttpStatusCode.NotFound => $"Nicht gefunden{FormatSuffix(problemTitle, detail, reason)}",
-            HttpStatusCode.Conflict => $"Konflikt{FormatSuffix(problemTitle, detail, reason)}",
-            HttpStatusCode.Unauthorized => $"Nicht autorisiert{FormatSuffix(problemTitle, detail, reason)}",
-            HttpStatusCode.Forbidden => $"Nicht erlaubt{FormatSuffix(problemTitle, detail, reason)}",
-            HttpStatusCode.InternalServerError => $"Serverfehler{FormatSuffix(problemTitle, detail, reason)}",
-            _ => $"Fehler {(int)status} {reason ?? string.Empty}{FormatSuffix(problemTitle, detail, reason)}"
-        };
-    }
-
-    private static string FormatSuffix(string? title, string? detail, string? reason)
-    {
-        var parts = new List<string>();
-        if (!string.IsNullOrWhiteSpace(title)) parts.Add(title);
-        if (!string.IsNullOrWhiteSpace(detail)) parts.Add(detail);
-        if (parts.Count == 0 && !string.IsNullOrWhiteSpace(reason)) parts.Add(reason);
-        if (parts.Count == 0) return string.Empty;
-        return ": " + string.Join(" | ", parts);
-    }
-}
-
-public record ApiResult<T>(bool Success, T? Value, string? Error)
-{
-    public static ApiResult<T> Ok(T? value) => new(true, value, null);
-    public static ApiResult<T> Fail(string? error) => new(false, default, error);
-}
-
-internal sealed class ProblemDetailsDto
-{
-    public string? Type { get; set; }
-    public string? Title { get; set; }
-    public string? Detail { get; set; }
-}
+}

DbFirst.BlazorWebApp/Services/DashboardApiClient.cs

@@ -1,9 +1,8 @@
-using System.Net.Http.Json;
 using DbFirst.BlazorWebApp.Models;
 
 namespace DbFirst.BlazorWebApp.Services;
 
-public class DashboardApiClient
+public class DashboardApiClient : IDashboardApiClient
 {
     private readonly HttpClient _httpClient;
     private const string Endpoint = "api/dashboard/dashboards";
@@ -13,9 +12,9 @@ public class DashboardApiClient
         _httpClient = httpClient;
     }
 
-    public async Task<List<DashboardInfoDto>> GetAllAsync()
+    public async Task<List<DashboardInfoDto>> GetAllAsync(CancellationToken ct = default)
     {
-        var result = await _httpClient.GetFromJsonAsync<List<DashboardInfoDto>>(Endpoint);
-        return result ?? new List<DashboardInfoDto>();
+        var result = await _httpClient.GetFromJsonAsync<List<DashboardInfoDto>>(Endpoint, ct);
+        return result ?? [];
     }
 }

DbFirst.BlazorWebApp/Services/ICatalogApiClient.cs

@@ -0,0 +1,12 @@
+using DbFirst.BlazorWebApp.Models;
+
+namespace DbFirst.BlazorWebApp.Services;
+
+public interface ICatalogApiClient
+{
+    Task<List<CatalogReadDto>> GetAllAsync(CancellationToken ct = default);
+    Task<CatalogReadDto?> GetByIdAsync(int id, CancellationToken ct = default);
+    Task<ApiResult<CatalogReadDto?>> CreateAsync(CatalogWriteDto dto, CancellationToken ct = default);
+    Task<ApiResult<bool>> UpdateAsync(int id, CatalogWriteDto dto, CancellationToken ct = default);
+    Task<ApiResult<bool>> DeleteAsync(int id, CancellationToken ct = default);
+}

DbFirst.BlazorWebApp/Services/IDashboardApiClient.cs

@@ -0,0 +1,9 @@
+using DbFirst.BlazorWebApp.Models;
+
+namespace DbFirst.BlazorWebApp.Services
+{
+    public interface IDashboardApiClient
+    {
+        Task<List<DashboardInfoDto>> GetAllAsync(CancellationToken ct = default);
+    }
+}

DbFirst.BlazorWebApp/Services/ILayoutApiClient.cs

@@ -0,0 +1,11 @@
+using DbFirst.BlazorWebApp.Models;
+
+namespace DbFirst.BlazorWebApp.Services
+{
+    public interface ILayoutApiClient
+    {
+        Task<LayoutDto?> GetAsync(string layoutType, string layoutKey, string userName, CancellationToken ct = default);
+        Task<LayoutDto> UpsertAsync(LayoutDto dto, CancellationToken ct = default);
+        Task DeleteAsync(string layoutType, string layoutKey, string userName, CancellationToken ct = default);
+    }
+}

DbFirst.BlazorWebApp/Services/IMassDataApiClient.cs

@@ -0,0 +1,12 @@
+using DbFirst.BlazorWebApp.Models;
+
+namespace DbFirst.BlazorWebApp.Services
+{
+    public interface IMassDataApiClient
+    {
+        Task<int> GetCountAsync(CancellationToken ct = default);
+        Task<List<MassDataReadDto>> GetAllAsync(int? skip, int? take, CancellationToken ct = default);
+        Task<ApiResult<MassDataReadDto?>> UpsertAsync(MassDataWriteDto dto, CancellationToken ct = default);
+        Task<MassDataReadDto?> GetByCustomerNameAsync(string customerName, CancellationToken ct = default);
+    }
+}

DbFirst.BlazorWebApp/Services/LayoutApiClient.cs

@@ -1,9 +1,8 @@
-using System.Net.Http.Json;
 using DbFirst.BlazorWebApp.Models;
 
 namespace DbFirst.BlazorWebApp.Services;
 
-public class LayoutApiClient
+public class LayoutApiClient : ILayoutApiClient
 {
     private readonly HttpClient _httpClient;
     private const string Endpoint = "api/layouts";
@@ -13,10 +12,10 @@ public class LayoutApiClient
         _httpClient = httpClient;
     }
 
-    public async Task<LayoutDto?> GetAsync(string layoutType, string layoutKey, string userName)
+    public async Task<LayoutDto?> GetAsync(string layoutType, string layoutKey, string userName, CancellationToken ct = default)
     {
         var url = $"{Endpoint}?layoutType={Uri.EscapeDataString(layoutType)}&layoutKey={Uri.EscapeDataString(layoutKey)}&userName={Uri.EscapeDataString(userName)}";
-        var response = await _httpClient.GetAsync(url);
+        var response = await _httpClient.GetAsync(url, ct);
         if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
         {
             return null;
@@ -26,12 +25,12 @@ public class LayoutApiClient
         return await response.Content.ReadFromJsonAsync<LayoutDto>();
     }
 
-    public async Task<LayoutDto> UpsertAsync(LayoutDto dto)
+    public async Task<LayoutDto> UpsertAsync(LayoutDto dto, CancellationToken ct = default)
     {
-        var response = await _httpClient.PostAsJsonAsync(Endpoint, dto);
+        var response = await _httpClient.PostAsJsonAsync(Endpoint, dto, ct);
         if (!response.IsSuccessStatusCode)
         {
-            var detail = await ReadErrorAsync(response);
+            var detail = await ApiClientHelper.ReadErrorAsync(response);
             throw new InvalidOperationException(detail);
         }
 
@@ -39,21 +38,10 @@ public class LayoutApiClient
         return payload ?? dto;
     }
 
-    private static async Task<string> ReadErrorAsync(HttpResponseMessage response)
-    {
-        var body = await response.Content.ReadAsStringAsync();
-        if (!string.IsNullOrWhiteSpace(body))
-        {
-            return body;
-        }
-
-        return $"{(int)response.StatusCode} {response.ReasonPhrase}".Trim();
-    }
-
-    public async Task DeleteAsync(string layoutType, string layoutKey, string userName)
+    public async Task DeleteAsync(string layoutType, string layoutKey, string userName, CancellationToken ct = default)
     {
         var url = $"{Endpoint}?layoutType={Uri.EscapeDataString(layoutType)}&layoutKey={Uri.EscapeDataString(layoutKey)}&userName={Uri.EscapeDataString(userName)}";
-        var response = await _httpClient.DeleteAsync(url);
+        var response = await _httpClient.DeleteAsync(url, ct);
         if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
         {
             return;

DbFirst.BlazorWebApp/Services/MassDataApiClient.cs

@@ -1,9 +1,8 @@
-using System.Net.Http.Json;
 using DbFirst.BlazorWebApp.Models;
 
 namespace DbFirst.BlazorWebApp.Services;
 
-public class MassDataApiClient
+public class MassDataApiClient : IMassDataApiClient
 {
     private readonly HttpClient _httpClient;
     private const string Endpoint = "api/massdata";
@@ -13,13 +12,13 @@ public class MassDataApiClient
         _httpClient = httpClient;
     }
 
-    public async Task<int> GetCountAsync()
+    public async Task<int> GetCountAsync(CancellationToken ct = default)
     {
-        var result = await _httpClient.GetFromJsonAsync<int?>("api/massdata/count");
+        var result = await _httpClient.GetFromJsonAsync<int?>("api/massdata/count", ct);
         return result ?? 0;
     }
 
-    public async Task<List<MassDataReadDto>> GetAllAsync(int? skip, int? take)
+    public async Task<List<MassDataReadDto>> GetAllAsync(int? skip, int? take, CancellationToken ct = default)
     {
         var query = new List<string>();
         if (skip.HasValue)
@@ -32,26 +31,31 @@ public class MassDataApiClient
         }
 
         var url = query.Count == 0 ? Endpoint : $"{Endpoint}?{string.Join("&", query)}";
-        var result = await _httpClient.GetFromJsonAsync<List<MassDataReadDto>>(url);
-        return result ?? new List<MassDataReadDto>();
+        var result = await _httpClient.GetFromJsonAsync<List<MassDataReadDto>>(url, ct);
+        return result ?? [];
     }
 
-    public async Task<MassDataReadDto> UpsertAsync(MassDataWriteDto dto)
+    public async Task<ApiResult<MassDataReadDto?>> UpsertAsync(MassDataWriteDto dto, CancellationToken ct = default)
     {
-        var response = await _httpClient.PostAsJsonAsync($"{Endpoint}/upsert", dto);
-        response.EnsureSuccessStatusCode();
-        var payload = await response.Content.ReadFromJsonAsync<MassDataReadDto>();
-        return payload ?? new MassDataReadDto();
+        var response = await _httpClient.PostAsJsonAsync($"{Endpoint}/upsert", dto, ct);
+        if (response.IsSuccessStatusCode)
+        {
+            var payload = await response.Content.ReadFromJsonAsync<MassDataReadDto>();
+            return ApiResult<MassDataReadDto?>.Ok(payload);
+        }
+
+        var error = await ApiClientHelper.ReadErrorAsync(response);
+        return ApiResult<MassDataReadDto?>.Fail(error);
     }
 
-    public async Task<MassDataReadDto?> GetByCustomerNameAsync(string customerName)
+    public async Task<MassDataReadDto?> GetByCustomerNameAsync(string customerName, CancellationToken ct = default)
     {
         if (string.IsNullOrWhiteSpace(customerName))
         {
             return null;
         }
 
-        var response = await _httpClient.GetAsync($"{Endpoint}/{Uri.EscapeDataString(customerName)}");
+        var response = await _httpClient.GetAsync($"{Endpoint}/{Uri.EscapeDataString(customerName)}", ct);
         if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
         {
             return null;

DbFirst.Domain/Entities/VwmyCatalog.cs

@@ -4,12 +4,12 @@ public partial class VwmyCatalog
 {
     public int Guid { get; set; }
 
-    public string CatTitle { get; set; } = null!;
+    public string CatTitle { get; set; } = string.Empty;
 
-    public string CatString { get; set; } = null!;
-
-    public string AddedWho { get; set; } = null!;
+    public string CatString { get; set; } = string.Empty;
 
+    public string AddedWho { get; set; } = string.Empty;
+    
     public DateTime AddedWhen { get; set; }
 
     public string? ChangedWho { get; set; }

DbFirst.Infrastructure/DbFirst.Infrastructure.csproj

@@ -15,7 +15,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Microsoft.Data.SqlClient" Version="5.2.1" />
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="8.0.2" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="10.0.0" />
     <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="8.0.0" />
   </ItemGroup>
 

DbFirst.Infrastructure/DependencyInjection.cs

@@ -1,3 +1,5 @@
+using DbFirst.Application.Repositories;
+using DbFirst.Infrastructure.Repositories;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -15,6 +17,10 @@ public static class DependencyInjection
         services.AddDbContext<MassDataDbContext>(options =>
             options.UseSqlServer(configuration.GetConnectionString("MassDataConnection")));
 
+        services.AddScoped<ICatalogRepository, CatalogRepository>();
+        services.AddScoped<IMassDataRepository, MassDataRepository>();
+        services.AddScoped<ILayoutRepository, LayoutRepository>();
+
         return services;
     }
 }

DbFirst.Infrastructure/Repositories/LayoutRepository.cs

@@ -34,7 +34,7 @@ public class LayoutRepository : ILayoutRepository
                 UserName = userName,
                 LayoutData = layoutData,
                 AddedWho = userName,
-                AddedWhen = DateTime.Now
+                AddedWhen = DateTime.UtcNow
             };
             _db.SmfLayouts.Add(entity);
         }

DbFirst.Infrastructure/Repositories/MassDataRepository.cs

@@ -20,11 +20,6 @@ public class MassDataRepository : IMassDataRepository
         return await _db.Massdata.AsNoTracking().CountAsync(cancellationToken);
     }
 
-    public async Task<List<Massdata>> GetAllAsync(CancellationToken cancellationToken = default)
-    {
-        return await _db.Massdata.AsNoTracking().ToListAsync(cancellationToken);
-    }
-
     public async Task<Massdata?> GetByCustomerNameAsync(string customerName, CancellationToken cancellationToken = default)
     {
         return await _db.Massdata.AsNoTracking()