Refactor MassDataGrid to use BandGridBase for layout logic

Move band and column management to BandGridBase, reducing duplication in MassDataGrid. Column definitions and layout key are now provided via overridden properties. Band editor actions now use feedback methods for user messages. Grid layout application and error display are streamlined. Improves maintainability and enables reuse across grid components.

DbFirst.BlazorWebApp/Components/BandGridBase.cs

@@ -0,0 +1,215 @@
+using DbFirst.BlazorWebApp.Models.Grid;
+using DbFirst.BlazorWebApp.Services;
+using DevExpress.Blazor;
+using Microsoft.AspNetCore.Components;
+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 bool bandEditorExpanded;
+    protected IGrid? gridRef;
+
+    // --- SizeMode ---
+    protected SizeMode _sizeMode = SizeMode.Medium;
+    protected static readonly List<SizeMode> _sizeModes = Enum.GetValues<SizeMode>().ToList();
+
+    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 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();
+        }
+        StateHasChanged();
+    }
+
+    protected 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 }));
+    }
+
+    // --- 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;
+        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();
+    }
+}

DbFirst.BlazorWebApp/Components/CatalogsGrid.razor

@@ -1,5 +1,5 @@
+@inherits BandGridBase<CatalogReadDto>
 @inject CatalogApiClient Api
-@inject BandLayoutService BandLayoutService
 
 @if (!string.IsNullOrWhiteSpace(errorMessage))
 {
@@ -34,8 +34,8 @@ else
             <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" />
+                    <DxButton Text="Layout speichern" Click="SaveLayoutWithFeedbackAsync" Enabled="@CanSaveBandLayout" />
+                    <DxButton Text="Layout zurücksetzen" Click="ResetLayoutWithFeedbackAsync" />
                 </div>
                 @foreach (var band in bandLayout.Bands)
                 {
@@ -45,7 +45,7 @@ else
                     </div>
                 }
                 <DxFormLayout CssClass="band-columns" ColCount="2">
-                    @foreach (var column in columnDefinitions)
+                    @foreach (var column in ColumnDefinitions)
                     {
                         <DxFormLayoutItem Caption="@column.Caption">
                             <DxComboBox Data="@bandOptions"
@@ -148,20 +148,12 @@ else
     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()
+    protected override string LayoutKey => "CatalogsGrid";
+
+    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 },
@@ -178,44 +170,15 @@ 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()
@@ -238,174 +201,6 @@ 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;
@@ -575,4 +370,25 @@ else
         public int Value { get; set; }
         public string Text { get; set; } = string.Empty;
     }
+
+    private async Task SaveLayoutWithFeedbackAsync()
+    {
+        try
+        {
+            await SaveLayoutAsync();
+            infoMessage = "Layout gespeichert.";
+            errorMessage = null;
+        }
+        catch (Exception ex)
+        {
+            errorMessage = $"Layout konnte nicht gespeichert werden: {ex.Message}";
+        }
+    }
+
+    private async Task ResetLayoutWithFeedbackAsync()
+    {
+        await ResetLayoutAsync();
+        infoMessage = "Layout zurückgesetzt.";
+        errorMessage = null;
+    }
 }

DbFirst.BlazorWebApp/Components/MassDataGrid.razor

@@ -1,5 +1,5 @@
+@inherits BandGridBase<MassDataReadDto>
 @inject MassDataApiClient Api
-@inject BandLayoutService BandLayoutService
 
 @if (!string.IsNullOrWhiteSpace(errorMessage))
 {
@@ -35,8 +35,8 @@ else
             <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" />
+                    <DxButton Text="Layout speichern" Click="SaveLayoutWithFeedbackAsync" Enabled="@CanSaveBandLayout" />
+                    <DxButton Text="Layout zurücksetzen" Click="ResetLayoutWithFeedbackAsync" />
                 </div>
                 @foreach (var band in bandLayout.Bands)
                 {
@@ -46,7 +46,7 @@ else
                     </div>
                 }
                 <DxFormLayout CssClass="band-columns" ColCount="2">
-                    @foreach (var column in columnDefinitions)
+                    @foreach (var column in ColumnDefinitions)
                     {
                         <DxFormLayoutItem Caption="@column.Caption">
                             <DxComboBox Data="@bandOptions"
@@ -178,19 +178,11 @@ else
     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()
+    protected override string LayoutKey => "MassDataGrid";
+
+    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 },
@@ -215,44 +207,15 @@ 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)
@@ -288,160 +251,6 @@ 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;
@@ -575,4 +384,25 @@ else
         public int? Value { get; set; }
         public string Text { get; set; } = string.Empty;
     }
+
+    private async Task SaveLayoutWithFeedbackAsync()
+    {
+        try
+        {
+            await SaveLayoutAsync();
+            infoMessage = "Layout gespeichert.";
+            errorMessage = null;
+        }
+        catch (Exception ex)
+        {
+            errorMessage = $"Layout konnte nicht gespeichert werden: {ex.Message}";
+        }
+    }
+
+    private async Task ResetLayoutWithFeedbackAsync()
+    {
+        await ResetLayoutAsync();
+        infoMessage = "Layout zurückgesetzt.";
+        errorMessage = null;
+    }
 }