Refactor: centralize grid band layout logic in service

Introduce BandLayoutService and shared models to manage grid band layouts across components. Refactor CatalogsGrid and MassDataGrid to use the new service, removing duplicated layout logic. Update _Imports.razor and register the service in Program.cs for improved maintainability and code reuse.

DbFirst.BlazorWebApp/Components/CatalogsGrid.razor

@@ -1,6 +1,5 @@
 @inject CatalogApiClient Api
-@inject LayoutApiClient LayoutApi
+@inject BandLayoutService BandLayoutService
-@inject IJSRuntime JsRuntime
 
 @if (!string.IsNullOrWhiteSpace(errorMessage))
 {
@@ -101,7 +100,9 @@ else
                 @RenderColumns()
             </Columns>
             <EditFormTemplate Context="editFormContext">
-                @{ SetEditContext(editFormContext.EditContext); var editModel = (CatalogEditModel)editFormContext.EditModel; SetPopupHeaderText(editModel.IsNew); }
+                @{
+                    SetEditContext(editFormContext.EditContext); var editModel = (CatalogEditModel)editFormContext.EditModel; SetPopupHeaderText(editModel.IsNew);
+                }
                 <DxFormLayout ColCount="2">
                     <DxFormLayoutItem Caption="Titel">
                         <DxTextBox @bind-Text="editModel.CatTitle" Width="100%" />
@@ -143,13 +144,13 @@ else
     private string popupHeaderText = "Edit";
     private const string LayoutType = "GRID_BANDS";
     private const string LayoutKey = "CatalogsGrid";
-    private const string LayoutUserStorageKey = "layoutUser";
     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 readonly JsonSerializerOptions jsonOptions = new(JsonSerializerDefaults.Web);
+    private bool gridLayoutApplied;
+
     private List<ColumnDefinition> columnDefinitions = new()
     {
         new() { FieldName = nameof(CatalogReadDto.Guid), Caption = "Id", Width = "140px", FilterType = ColumnFilterType.Text },
@@ -168,30 +169,32 @@ else
     };
 
     private bool CanSaveBandLayout => !string.IsNullOrWhiteSpace(layoutUser);
-    private bool gridLayoutApplied;
 
-    private DevExpress.Blazor.SizeMode _sizeMode = DevExpress.Blazor.SizeMode.Medium;
+    private SizeMode _sizeMode = SizeMode.Medium;
-    private static readonly List<DevExpress.Blazor.SizeMode> _sizeModes =
+    private static readonly List<SizeMode> _sizeModes = Enum.GetValues<SizeMode>().ToList();
-        Enum.GetValues<DevExpress.Blazor.SizeMode>().ToList();
 
-    private string FormatSizeText(DevExpress.Blazor.SizeMode size) => size switch
+    private string FormatSizeText(SizeMode size) => size switch
     {
-        DevExpress.Blazor.SizeMode.Small  => "Klein",
+        SizeMode.Small => "Klein",
-        DevExpress.Blazor.SizeMode.Medium => "Mittel",
+        SizeMode.Medium => "Mittel",
-        DevExpress.Blazor.SizeMode.Large  => "Groß",
+        SizeMode.Large => "Groß",
         _ => size.ToString()
     };
 
     private void OnSizeChange(DropDownButtonItemClickEventArgs args)
     {
-        _sizeMode = Enum.Parse<DevExpress.Blazor.SizeMode>(args.ItemInfo.Id);
+        _sizeMode = Enum.Parse<SizeMode>(args.ItemInfo.Id);
     }
 
     protected override async Task OnInitializedAsync()
     {
-        columnLookup = columnDefinitions.ToDictionary(column => column.FieldName, StringComparer.OrdinalIgnoreCase);
+        columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-        await EnsureLayoutUserAsync();
+        layoutUser = await BandLayoutService.EnsureLayoutUserAsync();
-        await LoadBandLayoutAsync();
+        bandLayout = await BandLayoutService.LoadBandLayoutAsync(LayoutType, LayoutKey, layoutUser, columnLookup);
+        columnBandAssignments = BandLayoutService.BuildAssignmentsFromLayout(bandLayout);
+        ApplyColumnLayoutFromStorage();
+        _sizeMode = bandLayout.SizeMode;
+        UpdateBandOptions();
         await LoadCatalogs();
     }
 
@@ -205,71 +208,6 @@ else
         }
     }
 
-    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)
-    {
-        if (validationMessageStore == null || editContext == null)
-        {
-            return;
-        }
-
-        if (e.FieldIdentifier.FieldName == nameof(CatalogEditModel.UpdateProcedure))
-        {
-            validationMessageStore.Clear();
-            editContext.NotifyValidationStateChanged();
-            return;
-        }
-
-        if (e.FieldIdentifier.FieldName == nameof(CatalogEditModel.CatTitle))
-        {
-            var field = new FieldIdentifier(editContext.Model, nameof(CatalogEditModel.CatTitle));
-            validationMessageStore.Clear(field);
-            editContext.NotifyValidationStateChanged();
-        }
-    }
-
-    private void SetPopupHeaderText(bool isNew)
-    {
-        popupHeaderText = isNew ? "Neu" : "Edit";
-    }
-
-    private void OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
-    {
-        popupHeaderText = e.IsNew ? "Neu" : "Edit";
-        if (e.IsNew)
-        {
-            e.EditModel = new CatalogEditModel { IsNew = true };
-            return;
-        }
-
-        var item = (CatalogReadDto)e.DataItem;
-        e.EditModel = new CatalogEditModel
-        {
-            Guid = item.Guid,
-            CatTitle = item.CatTitle,
-            CatString = item.CatString,
-            UpdateProcedure = 0,
-            OriginalCatTitle = item.CatTitle,
-            IsNew = false
-        };
-    }
-
     private async Task LoadCatalogs()
     {
         isLoading = true;
@@ -290,11 +228,229 @@ 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)
+    {
+        if (validationMessageStore == null || editContext == null) return;
+
+        if (e.FieldIdentifier.FieldName == nameof(CatalogEditModel.UpdateProcedure))
+        {
+            validationMessageStore.Clear();
+            editContext.NotifyValidationStateChanged();
+            return;
+        }
+
+        if (e.FieldIdentifier.FieldName == nameof(CatalogEditModel.CatTitle))
+        {
+            validationMessageStore.Clear(new FieldIdentifier(editContext.Model, nameof(CatalogEditModel.CatTitle)));
+            editContext.NotifyValidationStateChanged();
+        }
+    }
+
+    private void SetPopupHeaderText(bool isNew) => popupHeaderText = isNew ? "Neu" : "Edit";
+
+    private void OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
+    {
+        popupHeaderText = e.IsNew ? "Neu" : "Edit";
+        if (e.IsNew)
+        {
+            e.EditModel = new CatalogEditModel { IsNew = true };
+            return;
+        }
+
+        var item = (CatalogReadDto)e.DataItem;
+        e.EditModel = new CatalogEditModel
+        {
+            Guid = item.Guid,
+            CatTitle = item.CatTitle,
+            CatString = item.CatString,
+            UpdateProcedure = 0,
+            OriginalCatTitle = item.CatTitle,
+            IsNew = false
+        };
+    }
+
     private async Task OnEditModelSaving(GridEditModelSavingEventArgs e)
     {
         errorMessage = null;
         infoMessage = null;
-
         validationMessageStore?.Clear();
         editContext?.NotifyValidationStateChanged();
 
@@ -320,18 +476,12 @@ else
                 if (!created.Success || created.Value == null)
                 {
                     if (!string.IsNullOrWhiteSpace(created.Error))
-                    {
                         AddValidationError(editModel, nameof(CatalogEditModel.CatTitle), created.Error);
-                    }
                     else
-                    {
                         errorMessage = "Anlegen fehlgeschlagen.";
-                    }
-
                     e.Cancel = true;
                     return;
                 }
-
                 infoMessage = "Katalog angelegt.";
                 focusedRowKey = created.Value.Guid;
             }
@@ -344,7 +494,6 @@ else
                     e.Cancel = true;
                     return;
                 }
-
                 infoMessage = "Katalog aktualisiert.";
                 focusedRowKey = editModel.Guid;
             }
@@ -360,30 +509,20 @@ else
 
     private void AddValidationError(CatalogEditModel editModel, string fieldName, string message)
     {
-        if (editContext == null || validationMessageStore == null)
+        if (editContext == null || validationMessageStore == null) return;
-        {
+        validationMessageStore.Add(new FieldIdentifier(editModel, fieldName), message);
-            return;
-        }
-
-        var field = new FieldIdentifier(editModel, fieldName);
-        validationMessageStore.Add(field, message);
         editContext.NotifyValidationStateChanged();
     }
 
     private bool ValidateEditModel(CatalogEditModel editModel, bool isNew)
     {
-        if (isNew)
+        if (isNew) return true;
-        {
-            return true;
-        }
-
         if (editModel.UpdateProcedure == 0 &&
             !string.Equals(editModel.CatTitle, editModel.OriginalCatTitle, StringComparison.OrdinalIgnoreCase))
         {
             AddValidationError(editModel, nameof(CatalogEditModel.CatTitle), "Titel kann nicht geändert werden.");
             return false;
         }
-
         return true;
     }
 
@@ -391,9 +530,7 @@ else
     {
         errorMessage = null;
         infoMessage = null;
-
         var item = (CatalogReadDto)e.DataItem;
-
         try
         {
             var deleted = await Api.DeleteAsync(item.Guid);
@@ -403,350 +540,16 @@ else
                 e.Cancel = true;
                 return;
             }
-
             infoMessage = "Katalog gelöscht.";
             await LoadCatalogs();
         }
         catch (Exception ex)
         {
-            errorMessage = $"Fehler beim L&#246;schen: {ex.Message}";
+            errorMessage = $"Fehler beim Löschen: {ex.Message}";
             e.Cancel = true;
         }
     }
 
-    private async Task EnsureLayoutUserAsync()
-    {
-        layoutUser = await JsRuntime.InvokeAsync<string?>("localStorage.getItem", LayoutUserStorageKey);
-        if (string.IsNullOrWhiteSpace(layoutUser))
-        {
-            layoutUser = Guid.NewGuid().ToString("N");
-            await JsRuntime.InvokeVoidAsync("localStorage.setItem", LayoutUserStorageKey, layoutUser);
-        }
-    }
-
-    private async Task SaveLayoutAsync()
-    {
-        if (string.IsNullOrWhiteSpace(layoutUser))
-        {
-            return;
-        }
-
-        try
-        {
-            CaptureColumnLayoutFromGrid();
-
-            var layoutData = JsonSerializer.Serialize(bandLayout, jsonOptions);
-            await LayoutApi.UpsertAsync(new LayoutDto
-            {
-                LayoutType = LayoutType,
-                LayoutKey = LayoutKey,
-                UserName = layoutUser,
-                LayoutData = layoutData
-            });
-            infoMessage = "Layout gespeichert.";
-            errorMessage = null;
-        }
-        catch (Exception ex)
-        {
-            errorMessage = $"Layout konnte nicht gespeichert werden: {ex.Message}";
-        }
-    }
-
-    private void CaptureColumnLayoutFromGrid()
-    {
-        if (gridRef == null)
-        {
-            return;
-        }
-
-        var layout = gridRef.SaveLayout();
-        bandLayout.GridLayout = layout;
-        bandLayout.SizeMode = _sizeMode;
-
-        var orderedColumns = layout.Columns
-            .Where(column => !string.IsNullOrWhiteSpace(column.FieldName))
-            .OrderBy(column => column.VisibleIndex)
-            .ToList();
-
-        bandLayout.ColumnOrder = orderedColumns
-            .Select(column => column.FieldName)
-            .ToList();
-
-        bandLayout.ColumnWidths = orderedColumns
-            .Where(column => !string.IsNullOrWhiteSpace(column.Width))
-            .ToDictionary(column => column.FieldName, column => column.Width, StringComparer.OrdinalIgnoreCase);
-    }
-
-    private async Task LoadBandLayoutAsync()
-    {
-        if (string.IsNullOrWhiteSpace(layoutUser))
-        {
-            bandLayout = new BandLayout();
-            UpdateBandOptions();
-            return;
-        }
-
-        var stored = await LayoutApi.GetAsync(LayoutType, LayoutKey, layoutUser);
-        if (stored != null && !string.IsNullOrWhiteSpace(stored.LayoutData))
-        {
-            var parsed = JsonSerializer.Deserialize<BandLayout>(stored.LayoutData, jsonOptions);
-            bandLayout = NormalizeBandLayout(parsed);
-        }
-        else
-        {
-            bandLayout = new BandLayout();
-        }
-
-        columnBandAssignments = BuildAssignmentsFromLayout(bandLayout);
-        ApplyColumnLayoutFromStorage();
-        _sizeMode = bandLayout.SizeMode;
-        UpdateBandOptions();
-    }
-
-    private async Task ResetLayoutAsync()
-    {
-        if (string.IsNullOrWhiteSpace(layoutUser))
-        {
-            return;
-        }
-
-        await LayoutApi.DeleteAsync(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 = DevExpress.Blazor.SizeMode.Medium;
-
-        if (gridRef != null)
-            gridRef.LoadLayout(new GridPersistentLayout());
-        gridLayoutApplied = false;
-
-        infoMessage = "Layout zur\u00fcckgesetzt.";
-        errorMessage = null;
-    }
-
-    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(column => column.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);
-        var removedColumns = columnBandAssignments.Where(pair => pair.Value == band.Id)
-            .Select(pair => pair.Key)
-            .ToList();
-        foreach (var column in removedColumns)
-        {
-            columnBandAssignments.Remove(column);
-        }
-        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)
-    {
-        return columnBandAssignments.TryGetValue(fieldName, out var bandId) ? bandId : string.Empty;
-    }
-
-    private void SyncBandsFromAssignments()
-    {
-        foreach (var band in bandLayout.Bands)
-        {
-            band.Columns = columnDefinitions
-                .Where(column => columnBandAssignments.TryGetValue(column.FieldName, out var bandId) && bandId == band.Id)
-                .Select(column => column.FieldName)
-                .ToList();
-        }
-
-        StateHasChanged();
-    }
-
-    private void UpdateBandOptions()
-    {
-        bandOptions = new List<BandOption> { new() { Id = string.Empty, Caption = "Ohne Band" } };
-        bandOptions.AddRange(bandLayout.Bands.Select(band => new BandOption { Id = band.Id, Caption = band.Caption }));
-    }
-
-    private BandLayout NormalizeBandLayout(BandLayout? layout)
-    {
-        layout ??= new BandLayout();
-        layout.Bands ??= new List<BandDefinition>();
-        layout.ColumnOrder ??= new List<string>();
-        layout.ColumnWidths ??= new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase);
-        foreach (var band in layout.Bands)
-        {
-            if (string.IsNullOrWhiteSpace(band.Id))
-            {
-                band.Id = Guid.NewGuid().ToString("N");
-            }
-
-            if (string.IsNullOrWhiteSpace(band.Caption))
-            {
-                band.Caption = "Band";
-            }
-
-            band.Columns = band.Columns?.Where(columnLookup.ContainsKey).ToList() ?? new List<string>();
-        }
-
-        return layout;
-    }
-
-    private Dictionary<string, string> BuildAssignmentsFromLayout(BandLayout layout)
-    {
-        var assignments = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-        foreach (var band in layout.Bands)
-        {
-            foreach (var column in band.Columns)
-            {
-                assignments[column] = band.Id;
-            }
-        }
-
-        return assignments;
-    }
-
-    private RenderFragment RenderColumns() => builder =>
-    {
-        var seq = 0;
-        builder.OpenComponent<DxGridCommandColumn>(seq++);
-        builder.AddAttribute(seq++, "Width", "120px");
-        builder.CloseComponent();
-
-        var grouped = bandLayout.Bands.SelectMany(band => band.Columns).ToHashSet(StringComparer.OrdinalIgnoreCase);
-        foreach (var column in columnDefinitions.Where(column => !grouped.Contains(column.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 sealed class BandLayout
-    {
-        public List<BandDefinition> Bands { get; set; } = new();
-        public List<string> ColumnOrder { get; set; } = new();
-        public Dictionary<string, string?> ColumnWidths { get; set; } = new(StringComparer.OrdinalIgnoreCase);
-        public GridPersistentLayout? GridLayout { get; set; }
-        public DevExpress.Blazor.SizeMode SizeMode { get; set; } = DevExpress.Blazor.SizeMode.Medium;
-    }
-
-    private sealed class BandDefinition
-    {
-        public string Id { get; set; } = string.Empty;
-        public string Caption { get; set; } = string.Empty;
-        public List<string> Columns { get; set; } = new();
-    }
-
-    private sealed class BandOption
-    {
-        public string Id { get; set; } = string.Empty;
-        public string Caption { get; set; } = string.Empty;
-    }
-
-    private sealed class ColumnDefinition
-    {
-        public string FieldName { get; init; } = string.Empty;
-        public string Caption { get; init; } = string.Empty;
-        public string? Width { get; set; }
-        public string? DisplayFormat { get; init; }
-        public bool ReadOnly { get; init; }
-        public ColumnFilterType FilterType { get; init; }
-    }
-
-    private enum ColumnFilterType
-    {
-        Text,
-        Date
-    }
-
     private sealed class CatalogEditModel
     {
         public int Guid { get; set; }
@@ -762,10 +565,4 @@ else
         public int Value { get; set; }
         public string Text { get; set; } = string.Empty;
     }
-
+}
-    private sealed class FilterOperatorOption
-    {
-        public string Value { get; set; } = string.Empty;
-        public string Text { get; set; } = string.Empty;
-    }
-}

DbFirst.BlazorWebApp/Components/MassDataGrid.razor

@@ -1,6 +1,5 @@
 @inject MassDataApiClient Api
-@inject LayoutApiClient LayoutApi
+@inject BandLayoutService BandLayoutService
-@inject IJSRuntime JsRuntime
 
 @if (!string.IsNullOrWhiteSpace(errorMessage))
 {
@@ -113,7 +112,9 @@ else
                 @RenderColumns()
             </Columns>
             <EditFormTemplate Context="editFormContext">
-                @{ SetEditContext(editFormContext.EditContext); var editModel = (MassDataEditModel)editFormContext.EditModel; SetPopupHeaderText(editModel.IsNew); }
+                @{
+                    SetEditContext(editFormContext.EditContext); var editModel = (MassDataEditModel)editFormContext.EditModel; SetPopupHeaderText(editModel.IsNew);
+                }
                 <DxFormLayout ColCount="2">
                     <DxFormLayoutItem Caption="CustomerName">
                         <DxTextBox @bind-Text="editModel.CustomerName" Width="100%" />
@@ -171,13 +172,13 @@ else
     private int? focusedRowKey;
     private const string LayoutType = "GRID_BANDS";
     private const string LayoutKey = "MassDataGrid";
-    private const string LayoutUserStorageKey = "layoutUser";
     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 readonly JsonSerializerOptions jsonOptions = new(JsonSerializerDefaults.Web);
+    private bool gridLayoutApplied;
+
     private List<ColumnDefinition> columnDefinitions = new()
     {
         new() { FieldName = nameof(MassDataReadDto.Id), Caption = "Id", Width = "90px", ReadOnly = true, FilterType = ColumnFilterType.Text },
@@ -189,15 +190,13 @@ else
         new() { FieldName = nameof(MassDataReadDto.ChangedWhen), Caption = "Changed", ReadOnly = true, FilterType = ColumnFilterType.Date }
     };
 
-    private bool CanSaveBandLayout => !string.IsNullOrWhiteSpace(layoutUser);
-
     private readonly List<PageSizeOption> pageSizeOptions = new()
     {
-        new() { Value = 100, Text = "100" },
+        new() { Value = 100,    Text = "100" },
-        new() { Value = 1000, Text = "1.000" },
+        new() { Value = 1000,   Text = "1.000" },
-        new() { Value = 10000, Text = "10.000" },
+        new() { Value = 10000,  Text = "10.000" },
         new() { Value = 100000, Text = "100.000" },
-        new() { Value = null, Text = "Alle" }
+        new() { Value = null,   Text = "Alle" }
     };
 
     private readonly List<ProcedureOption> procedureOptions = new()
@@ -205,33 +204,46 @@ else
         new() { Value = 0, Text = "PRMassdata_UpsertByCustomerName" }
     };
 
-    private bool gridLayoutApplied;
+    private bool CanSaveBandLayout => !string.IsNullOrWhiteSpace(layoutUser);
 
-    private DevExpress.Blazor.SizeMode _sizeMode = DevExpress.Blazor.SizeMode.Medium;
+    private SizeMode _sizeMode = SizeMode.Medium;
-    private static readonly List<DevExpress.Blazor.SizeMode> _sizeModes =
+    private static readonly List<SizeMode> _sizeModes = Enum.GetValues<SizeMode>().ToList();
-        Enum.GetValues<DevExpress.Blazor.SizeMode>().ToList();
 
-    private string FormatSizeText(DevExpress.Blazor.SizeMode size) => size switch
+    private string FormatSizeText(SizeMode size) => size switch
     {
-        DevExpress.Blazor.SizeMode.Small  => "Klein",
+        SizeMode.Small => "Klein",
-        DevExpress.Blazor.SizeMode.Medium => "Mittel",
+        SizeMode.Medium => "Mittel",
-        DevExpress.Blazor.SizeMode.Large  => "Groß",
+        SizeMode.Large => "Groß",
         _ => size.ToString()
     };
 
     private void OnSizeChange(DropDownButtonItemClickEventArgs args)
     {
-        _sizeMode = Enum.Parse<DevExpress.Blazor.SizeMode>(args.ItemInfo.Id);
+        _sizeMode = Enum.Parse<SizeMode>(args.ItemInfo.Id);
     }
 
     protected override async Task OnInitializedAsync()
     {
-        columnLookup = columnDefinitions.ToDictionary(column => column.FieldName, StringComparer.OrdinalIgnoreCase);
+        columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-        await EnsureLayoutUserAsync();
+        layoutUser = await BandLayoutService.EnsureLayoutUserAsync();
-        await LoadBandLayoutAsync();
+        bandLayout = await BandLayoutService.LoadBandLayoutAsync(LayoutType, LayoutKey, layoutUser, columnLookup);
+        columnBandAssignments = BandLayoutService.BuildAssignmentsFromLayout(bandLayout);
+        ApplyColumnLayoutFromStorage();
+        _sizeMode = bandLayout.SizeMode;
+        UpdateBandOptions();
         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);
+        }
+    }
+
     private async Task LoadPage(int page)
     {
         isLoading = true;
@@ -242,7 +254,6 @@ else
             var effectivePageSize = pageSize ?? (total == 0 ? 1 : total);
             pageCount = Math.Max(1, (int)Math.Ceiling(total / (double)effectivePageSize));
             pageIndex = Math.Clamp(page, 0, pageCount - 1);
-
             var skip = pageSize.HasValue ? pageIndex * pageSize.Value : 0;
             items = await Api.GetAllAsync(skip, pageSize);
         }
@@ -258,10 +269,7 @@ else
         }
     }
 
-    private async Task OnPageChanged(int index)
+    private async Task OnPageChanged(int index) => await LoadPage(index);
-    {
-        await LoadPage(index);
-    }
 
     private async Task OnPageSizeChanged(int? size)
     {
@@ -269,61 +277,15 @@ else
         await LoadPage(0);
     }
 
-    private async Task EnsureLayoutUserAsync()
-    {
-        layoutUser = await JsRuntime.InvokeAsync<string?>("localStorage.getItem", LayoutUserStorageKey);
-        if (string.IsNullOrWhiteSpace(layoutUser))
-        {
-            layoutUser = Guid.NewGuid().ToString("N");
-            await JsRuntime.InvokeVoidAsync("localStorage.setItem", LayoutUserStorageKey, layoutUser);
-        }
-    }
-
-    private async Task LoadBandLayoutAsync()
-    {
-        if (string.IsNullOrWhiteSpace(layoutUser))
-        {
-            bandLayout = new BandLayout();
-            UpdateBandOptions();
-            return;
-        }
-
-        var stored = await LayoutApi.GetAsync(LayoutType, LayoutKey, layoutUser);
-        if (stored != null && !string.IsNullOrWhiteSpace(stored.LayoutData))
-        {
-            var parsed = JsonSerializer.Deserialize<BandLayout>(stored.LayoutData, jsonOptions);
-            bandLayout = NormalizeBandLayout(parsed);
-        }
-        else
-        {
-            bandLayout = new BandLayout();
-        }
-
-        columnBandAssignments = BuildAssignmentsFromLayout(bandLayout);
-        ApplyColumnLayoutFromStorage();
-        _sizeMode = bandLayout.SizeMode;
-        UpdateBandOptions();
-    }
-
     private async Task SaveLayoutAsync()
     {
         if (string.IsNullOrWhiteSpace(layoutUser))
-        {
             return;
-        }
 
         try
         {
             CaptureColumnLayoutFromGrid();
-
+            await BandLayoutService.SaveBandLayoutAsync(LayoutType, LayoutKey, layoutUser, bandLayout);
-            var layoutData = JsonSerializer.Serialize(bandLayout, jsonOptions);
-            await LayoutApi.UpsertAsync(new LayoutDto
-            {
-                LayoutType = LayoutType,
-                LayoutKey = LayoutKey,
-                UserName = layoutUser,
-                LayoutData = layoutData
-            });
             infoMessage = "Layout gespeichert.";
             errorMessage = null;
         }
@@ -333,41 +295,12 @@ else
         }
     }
 
-    private void CaptureColumnLayoutFromGrid()
-    {
-        if (gridRef == null)
-        {
-            return;
-        }
-
-        var layout = gridRef.SaveLayout();
-        bandLayout.GridLayout = layout;
-        bandLayout.SizeMode = _sizeMode;
-
-        var orderedColumns = layout.Columns
-            .Where(column => !string.IsNullOrWhiteSpace(column.FieldName))
-            .OrderBy(column => column.VisibleIndex)
-            .ToList();
-
-        bandLayout.ColumnOrder = orderedColumns
-            .Select(column => column.FieldName)
-            .ToList();
-
-        bandLayout.ColumnWidths = orderedColumns
-            .Where(column => !string.IsNullOrWhiteSpace(column.Width))
-            .ToDictionary(column => column.FieldName, column => column.Width, StringComparer.OrdinalIgnoreCase);
-
-        bandLayout.SizeMode = _sizeMode;
-    }
-
     private async Task ResetLayoutAsync()
     {
         if (string.IsNullOrWhiteSpace(layoutUser))
-        {
             return;
-        }
 
-        await LayoutApi.DeleteAsync(LayoutType, LayoutKey, layoutUser);
+        await BandLayoutService.ResetBandLayoutAsync(LayoutType, LayoutKey, layoutUser);
 
         bandLayout = new BandLayout();
         columnBandAssignments.Clear();
@@ -377,49 +310,57 @@ else
             column.Width = null;
         columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
 
-        _sizeMode = DevExpress.Blazor.SizeMode.Medium;
+        _sizeMode = SizeMode.Medium;
 
         if (gridRef != null)
             gridRef.LoadLayout(new GridPersistentLayout());
         gridLayoutApplied = false;
 
-        infoMessage = "Layout zur\u00fcckgesetzt.";
+        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);
-        columnLookup = columnDefinitions.ToDictionary(column => column.FieldName, StringComparer.OrdinalIgnoreCase);
     }
 
     private void AddBand()
     {
-        bandLayout.Bands.Add(new BandDefinition
+        bandLayout.Bands.Add(new BandDefinition { Id = Guid.NewGuid().ToString("N"), Caption = "Band" });
-        {
-            Id = Guid.NewGuid().ToString("N"),
-            Caption = "Band"
-        });
         UpdateBandOptions();
     }
 
     private void RemoveBand(BandDefinition band)
     {
         bandLayout.Bands.Remove(band);
-        var removedColumns = columnBandAssignments.Where(pair => pair.Value == band.Id)
+        foreach (var key in columnBandAssignments.Where(p => p.Value == band.Id).Select(p => p.Key).ToList())
-            .Select(pair => pair.Key)
+            columnBandAssignments.Remove(key);
-            .ToList();
-        foreach (var column in removedColumns)
-        {
-            columnBandAssignments.Remove(column);
-        }
         UpdateBandOptions();
         SyncBandsFromAssignments();
     }
@@ -433,77 +374,31 @@ else
     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;
-        return columnBandAssignments.TryGetValue(fieldName, out var bandId) ? bandId : string.Empty;
-    }
 
     private void SyncBandsFromAssignments()
     {
         foreach (var band in bandLayout.Bands)
         {
             band.Columns = columnDefinitions
-                .Where(column => columnBandAssignments.TryGetValue(column.FieldName, out var bandId) && bandId == band.Id)
+                .Where(c => columnBandAssignments.TryGetValue(c.FieldName, out var id) && id == band.Id)
-                .Select(column => column.FieldName)
+                .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(band => new BandOption { Id = band.Id, Caption = band.Caption }));
+        bandOptions.AddRange(bandLayout.Bands.Select(b => new BandOption { Id = b.Id, Caption = b.Caption }));
-    }
-
-    private Dictionary<string, string> BuildAssignmentsFromLayout(BandLayout layout)
-    {
-        var assignments = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-        foreach (var band in layout.Bands)
-        {
-            foreach (var column in band.Columns)
-            {
-                assignments[column] = band.Id;
-            }
-        }
-
-        return assignments;
-    }
-
-    private BandLayout NormalizeBandLayout(BandLayout? layout)
-    {
-        layout ??= new BandLayout();
-        layout.Bands ??= new List<BandDefinition>();
-        layout.ColumnOrder ??= new List<string>();
-        layout.ColumnWidths ??= new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase);
-        foreach (var band in layout.Bands)
-        {
-            if (string.IsNullOrWhiteSpace(band.Id))
-            {
-                band.Id = Guid.NewGuid().ToString("N");
-            }
-
-            if (string.IsNullOrWhiteSpace(band.Caption))
-            {
-                band.Caption = "Band";
-            }
-
-            band.Columns = band.Columns?.Where(columnLookup.ContainsKey).ToList() ?? new List<string>();
-        }
-
-        return layout;
     }
 
     private RenderFragment RenderColumns() => builder =>
@@ -513,18 +408,13 @@ else
         builder.AddAttribute(seq++, "Width", "120px");
         builder.CloseComponent();
 
-        var grouped = bandLayout.Bands.SelectMany(band => band.Columns).ToHashSet(StringComparer.OrdinalIgnoreCase);
+        var grouped = bandLayout.Bands.SelectMany(b => b.Columns).ToHashSet(StringComparer.OrdinalIgnoreCase);
-        foreach (var column in columnDefinitions.Where(column => !grouped.Contains(column.FieldName)))
+        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)
+            if (band.Columns.Count == 0) continue;
-            {
-                continue;
-            }
 
             builder.OpenComponent<DxGridBandColumn>(seq++);
             builder.AddAttribute(seq++, "Caption", band.Caption);
@@ -534,9 +424,7 @@ else
                 foreach (var columnName in band.Columns)
                 {
                     if (columnLookup.TryGetValue(columnName, out var column))
-                    {
                         BuildDataColumn(bandBuilder, ref bandSeq, column);
-                    }
                 }
             }));
             builder.CloseComponent();
@@ -549,35 +437,19 @@ else
         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)
+        if (editContext == context) return;
-        {
-            return;
-        }
-
         if (editContext != null)
-        {
             editContext.OnFieldChanged -= OnEditFieldChanged;
-        }
-
         editContext = context;
         validationMessageStore = new ValidationMessageStore(editContext);
         editContext.OnFieldChanged += OnEditFieldChanged;
@@ -585,10 +457,7 @@ else
 
     private void OnEditFieldChanged(object? sender, FieldChangedEventArgs e)
     {
-        if (validationMessageStore == null || editContext == null)
+        if (validationMessageStore == null || editContext == null) return;
-        {
-            return;
-        }
 
         if (e.FieldIdentifier.FieldName == nameof(MassDataEditModel.UpdateProcedure))
         {
@@ -599,16 +468,12 @@ else
 
         if (e.FieldIdentifier.FieldName == nameof(MassDataEditModel.CustomerName))
         {
-            var field = new FieldIdentifier(editContext.Model, nameof(MassDataEditModel.CustomerName));
+            validationMessageStore.Clear(new FieldIdentifier(editContext.Model, nameof(MassDataEditModel.CustomerName)));
-            validationMessageStore.Clear(field);
             editContext.NotifyValidationStateChanged();
         }
     }
 
-    private void SetPopupHeaderText(bool isNew)
+    private void SetPopupHeaderText(bool isNew) => popupHeaderText = isNew ? "Neu" : "Edit";
-    {
-        popupHeaderText = isNew ? "Neu" : "Edit";
-    }
 
     private async Task OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
     {
@@ -638,7 +503,6 @@ else
     {
         errorMessage = null;
         infoMessage = null;
-
         validationMessageStore?.Clear();
         editContext?.NotifyValidationStateChanged();
 
@@ -685,13 +549,8 @@ else
 
     private void AddValidationError(MassDataEditModel editModel, string fieldName, string message)
     {
-        if (editContext == null || validationMessageStore == null)
+        if (editContext == null || validationMessageStore == null) return;
-        {
+        validationMessageStore.Add(new FieldIdentifier(editModel, fieldName), message);
-            return;
-        }
-
-        var field = new FieldIdentifier(editModel, fieldName);
-        validationMessageStore.Add(field, message);
         editContext.NotifyValidationStateChanged();
     }
 
@@ -703,55 +562,6 @@ else
         return Task.CompletedTask;
     }
 
-    protected override async Task OnAfterRenderAsync(bool firstRender)
-    {
-        if (!gridLayoutApplied && gridRef != null && bandLayout.GridLayout != null)
-        {
-            gridRef.LoadLayout(bandLayout.GridLayout);
-            gridLayoutApplied = true;
-            await InvokeAsync(StateHasChanged);
-        }
-    }
-
-    private sealed class BandLayout
-    {
-        public List<BandDefinition> Bands { get; set; } = new();
-        public List<string> ColumnOrder { get; set; } = new();
-        public Dictionary<string, string?> ColumnWidths { get; set; } = new(StringComparer.OrdinalIgnoreCase);
-        public GridPersistentLayout? GridLayout { get; set; }
-        public DevExpress.Blazor.SizeMode SizeMode { get; set; } = DevExpress.Blazor.SizeMode.Medium;
-    }
-
-    private sealed class BandDefinition
-    {
-        public string Id { get; set; } = string.Empty;
-        public string Caption { get; set; } = string.Empty;
-        public List<string> Columns { get; set; } = new();
-    }
-
-    private sealed class BandOption
-    {
-        public string Id { get; set; } = string.Empty;
-        public string Caption { get; set; } = string.Empty;
-    }
-
-    private sealed class ColumnDefinition
-    {
-        public string FieldName { get; init; } = string.Empty;
-        public string Caption { get; init; } = string.Empty;
-        public string? Width { get; set; }
-        public string? DisplayFormat { get; init; }
-        public bool ReadOnly { get; init; }
-        public ColumnFilterType FilterType { get; init; }
-    }
-
-    private enum ColumnFilterType
-    {
-        Text,
-        Bool,
-        Date
-    }
-
     private sealed class MassDataEditModel
     {
         public int Id { get; set; }
@@ -770,21 +580,9 @@ else
         public string Text { get; set; } = string.Empty;
     }
 
-    private sealed class BoolFilterOption
-    {
-        public bool? Value { get; set; }
-        public string Text { get; set; } = string.Empty;
-    }
-
     private sealed class PageSizeOption
     {
         public int? Value { get; set; }
         public string Text { get; set; } = string.Empty;
     }
-
+}
-    private sealed class FilterOperatorOption
-    {
-        public string Value { get; set; } = string.Empty;
-        public string Text { get; set; } = string.Empty;
-    }
-}

DbFirst.BlazorWebApp/Components/_Imports.razor

@@ -1,5 +1,6 @@
 @using System.Net.Http
 @using System.Net.Http.Json
+@using System.Text.Json
 @using Microsoft.AspNetCore.Components.Forms
 @using Microsoft.AspNetCore.Components.Rendering
 @using Microsoft.AspNetCore.Components.Routing
@@ -11,10 +12,9 @@
 @using DbFirst.BlazorWebApp
 @using DbFirst.BlazorWebApp.Components
 @using DbFirst.BlazorWebApp.Models
+@using DbFirst.BlazorWebApp.Models.Grid
 @using DbFirst.BlazorWebApp.Services
 @using DevExpress.Blazor
 @using DevExpress.DashboardBlazor
 @using DevExpress.DashboardWeb
-@using DevExpress.Data.Filtering
+@using DevExpress.Data.Filtering
-@using DbFirst.BlazorWebApp
-@using System.Text.Json

DbFirst.BlazorWebApp/Models/Grid/BandLayoutModels.cs

@@ -0,0 +1,43 @@
+using DevExpress.Blazor;
+
+namespace DbFirst.BlazorWebApp.Models.Grid
+{
+    public class BandLayout
+    {
+        public List<BandDefinition> Bands { get; set; } = new();
+        public List<string> ColumnOrder { get; set; } = new();
+        public Dictionary<string, string?> ColumnWidths { get; set; } = new(StringComparer.OrdinalIgnoreCase);
+        public GridPersistentLayout? GridLayout { get; set; }
+        public SizeMode SizeMode { get; set; } = SizeMode.Medium;
+    }
+
+    public class BandDefinition
+    {
+        public string Id { get; set; } = string.Empty;
+        public string Caption { get; set; } = string.Empty;
+        public List<string> Columns { get; set; } = new();
+    }
+
+    public class BandOption
+    {
+        public string Id { get; set; } = string.Empty;
+        public string Caption { get; set; } = string.Empty;
+    }
+
+    public class ColumnDefinition
+    {
+        public string FieldName { get; init; } = string.Empty;
+        public string Caption { get; init; } = string.Empty;
+        public string? Width { get; set; }
+        public string? DisplayFormat { get; init; }
+        public bool ReadOnly { get; init; }
+        public ColumnFilterType FilterType { get; init; }
+    }
+
+    public enum ColumnFilterType
+    {
+        Text,
+        Bool,
+        Date
+    }
+}

DbFirst.BlazorWebApp/Program.cs

@@ -10,6 +10,7 @@ builder.Services.AddRazorComponents()
 
 builder.Services.AddDevExpressBlazor(options => options.BootstrapVersion = BootstrapVersion.v5);
 builder.Services.AddScoped<ThemeState>();
+builder.Services.AddScoped<BandLayoutService>();
 
 var apiBaseUrl = builder.Configuration["ApiBaseUrl"];
 if (!string.IsNullOrWhiteSpace(apiBaseUrl))

DbFirst.BlazorWebApp/Services/BandLayoutService.cs

@@ -0,0 +1,103 @@
+using DbFirst.BlazorWebApp.Models;
+using DbFirst.BlazorWebApp.Models.Grid;
+using Microsoft.JSInterop;
+using System.Text.Json;
+
+namespace DbFirst.BlazorWebApp.Services
+{
+    public class BandLayoutService(LayoutApiClient layoutApi, IJSRuntime jsRuntime)
+    {
+        private const string LayoutUserStorageKey = "layoutUser";
+        private readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
+
+        public async Task<string> EnsureLayoutUserAsync()
+        {
+            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;
+        }
+
+        public async Task<BandLayout> LoadBandLayoutAsync(
+            string layoutType,
+            string layoutKey,
+            string layoutUser,
+            Dictionary<string, ColumnDefinition> columnLookup)
+        {
+            if (string.IsNullOrWhiteSpace(layoutUser))
+                return new BandLayout();
+
+            var stored = await layoutApi.GetAsync(layoutType, layoutKey, layoutUser);
+            if (stored != null && !string.IsNullOrWhiteSpace(stored.LayoutData))
+            {
+                var parsed = JsonSerializer.Deserialize<BandLayout>(stored.LayoutData, _jsonOptions);
+                return NormalizeBandLayout(parsed, columnLookup);
+            }
+
+            return new BandLayout();
+        }
+
+        public async Task SaveBandLayoutAsync(
+            string layoutType,
+            string layoutKey,
+            string layoutUser,
+            BandLayout bandLayout)
+        {
+            var layoutData = JsonSerializer.Serialize(bandLayout, _jsonOptions);
+            await layoutApi.UpsertAsync(new LayoutDto
+            {
+                LayoutType = layoutType,
+                LayoutKey = layoutKey,
+                UserName = layoutUser,
+                LayoutData = layoutData
+            });
+        }
+
+        public async Task ResetBandLayoutAsync(
+            string layoutType,
+            string layoutKey,
+            string layoutUser)
+        {
+            await layoutApi.DeleteAsync(layoutType, layoutKey, layoutUser);
+        }
+
+        public Dictionary<string, string> BuildAssignmentsFromLayout(BandLayout layout)
+        {
+            var assignments = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            foreach (var band in layout.Bands)
+            {
+                foreach (var column in band.Columns)
+                {
+                    assignments[column] = band.Id;
+                }
+            }
+            return assignments;
+        }
+
+        public BandLayout NormalizeBandLayout(
+            BandLayout? layout,
+            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);
+
+            foreach (var band in layout.Bands)
+            {
+                if (string.IsNullOrWhiteSpace(band.Id))
+                    band.Id = Guid.NewGuid().ToString("N");
+
+                if (string.IsNullOrWhiteSpace(band.Caption))
+                    band.Caption = "Band";
+
+                band.Columns = band.Columns?.Where(columnLookup.ContainsKey).ToList() ?? new List<string>();
+            }
+
+            return layout;
+        }
+    }
+}