QuickGrid: Adds EmptyContentTemplate

src/Components/QuickGrid/Microsoft.AspNetCore.Components.QuickGrid/src/EmptyContentTemplate.razor

@@ -0,0 +1,6 @@
+@namespace Microsoft.AspNetCore.Components.QuickGrid
+@typeparam TGridItem
+
+@{
+    InternalGridContext.Grid.SetEmptyContent(this);
+}

src/Components/QuickGrid/Microsoft.AspNetCore.Components.QuickGrid/src/EmptyContentTemplate.razor.cs

@@ -0,0 +1,20 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Components.QuickGrid.Infrastructure;
+
+namespace Microsoft.AspNetCore.Components.QuickGrid;
+
+/// <summary>
+/// A component that is displayed when the <see cref="QuickGrid{TGridItem}"/> has no data available.
+/// </summary>
+/// <typeparam name="TGridItem">The type of data represented by each row in the grid.</typeparam>
+public partial class EmptyContentTemplate<TGridItem>
+{
+    [CascadingParameter] internal InternalGridContext<TGridItem> InternalGridContext { get; set; } = default!;
+
+    /// <summary>
+    /// Defines the content to be rendered by <see cref="QuickGrid{TGridItem}"/> when no data is available.
+    /// </summary>
+    [Parameter] public RenderFragment? ChildContent { get; set; }
+}

src/Components/QuickGrid/Microsoft.AspNetCore.Components.QuickGrid/src/PublicAPI.Unshipped.txt

@@ -1,4 +1,11 @@
 #nullable enable
+~override Microsoft.AspNetCore.Components.QuickGrid.EmptyContentTemplate<TGridItem>.BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder) -> void
+Microsoft.AspNetCore.Components.QuickGrid.EmptyContentTemplate<TGridItem>
+Microsoft.AspNetCore.Components.QuickGrid.EmptyContentTemplate<TGridItem>.ChildContent.get -> Microsoft.AspNetCore.Components.RenderFragment?
+Microsoft.AspNetCore.Components.QuickGrid.EmptyContentTemplate<TGridItem>.ChildContent.set -> void
+Microsoft.AspNetCore.Components.QuickGrid.EmptyContentTemplate<TGridItem>.EmptyContentTemplate() -> void
+Microsoft.AspNetCore.Components.QuickGrid.QuickGrid<TGridItem>.EmptyContent.get -> Microsoft.AspNetCore.Components.RenderFragment?
+Microsoft.AspNetCore.Components.QuickGrid.QuickGrid<TGridItem>.EmptyContent.set -> void
 Microsoft.AspNetCore.Components.QuickGrid.QuickGrid<TGridItem>.HideColumnOptionsAsync() -> System.Threading.Tasks.Task!
 Microsoft.AspNetCore.Components.QuickGrid.QuickGrid<TGridItem>.RowClass.get -> System.Func<TGridItem, string?>?
-Microsoft.AspNetCore.Components.QuickGrid.QuickGrid<TGridItem>.RowClass.set -> void
+Microsoft.AspNetCore.Components.QuickGrid.QuickGrid<TGridItem>.RowClass.set -> void

src/Components/QuickGrid/Microsoft.AspNetCore.Components.QuickGrid/src/QuickGrid.razor

@@ -20,12 +20,13 @@
                 @if (Virtualize)
                 {
                     <Virtualize @ref="@_virtualizeComponent"
-                        TItem="(int RowIndex, TGridItem Data)"
-                        ItemSize="@ItemSize"
-                        OverscanCount="@OverscanCount"
-                        ItemsProvider="@ProvideVirtualizedItems"
-                        ItemContent="@(item => builder => RenderRow(builder, item.RowIndex, item.Data))"
-                        Placeholder="@(placeholderContext => builder => RenderPlaceholderRow(builder, placeholderContext))" />
+                                TItem="(int RowIndex, TGridItem Data)"
+                                ItemSize="@ItemSize"
+                                OverscanCount="@OverscanCount"
+                                ItemsProvider="@ProvideVirtualizedItems"
+                                ItemContent="@(item => builder => RenderRow(builder, item.RowIndex, item.Data))"
+                                EmptyContent="@EmptyContent"
+                                Placeholder="@(placeholderContext => builder => RenderPlaceholderRow(builder, placeholderContext))" />
                 }
                 else
                 {
@@ -41,9 +42,17 @@
     {
         var initialRowIndex = 2; // aria-rowindex is 1-based, plus the first row is the header
         var rowIndex = initialRowIndex;
-        foreach (var item in _currentNonVirtualizedViewItems)
+
+        if (EmptyContent != null && _currentNonVirtualizedViewItems.Count == 0)
+        {
+            RenderEmptyRow(__builder, rowIndex++);
+        }
+        else
         {
-            RenderRow(__builder, rowIndex++, item);
+            foreach (var item in _currentNonVirtualizedViewItems)
+            {
+                RenderRow(__builder, rowIndex++, item);
+            }
         }
 
         // When pagination is enabled, by default ensure we render the exact number of expected rows per page,
@@ -63,6 +72,15 @@
         }
     }
 
+    private void RenderEmptyRow(RenderTreeBuilder __builder, int rowIndex)
+    {
+        <tr aria-rowindex="@rowIndex">
+            <td colspan="@_columns.Count">
+                @EmptyContent
+            </td>
+        </tr>
+    }
+
     private void RenderRow(RenderTreeBuilder __builder, int rowIndex, TGridItem item)
     {
         var rowClass = RowClass?.Invoke(item);

src/Components/QuickGrid/Microsoft.AspNetCore.Components.QuickGrid/src/QuickGrid.razor.cs

@@ -124,6 +124,13 @@ public partial class QuickGrid<TGridItem> : IAsyncDisposable
     // We cascade the InternalGridContext to descendants, which in turn call it to add themselves to _columns
     // This happens on every render so that the column list can be updated dynamically
     private readonly InternalGridContext<TGridItem> _internalGridContext;
+
+    /// <summary>
+    /// Gets or sets a <see cref="RenderFragment" /> that will be rendered when no data is available to display.
+    /// This allows derived components to specify a default if the user does not specify it.
+    /// </summary>
+    protected internal RenderFragment? EmptyContent { get; protected set; }
+
     private readonly List<ColumnBase<TGridItem>> _columns;
     private bool _collectingColumns; // Columns might re-render themselves arbitrarily. We only want to capture them at a defined time.
 
@@ -216,6 +223,11 @@ protected override async Task OnAfterRenderAsync(bool firstRender)
         }
     }
 
+    internal void SetEmptyContent(EmptyContentTemplate<TGridItem> emptyContentTemplate)
+    {
+        EmptyContent = emptyContentTemplate.ChildContent;
+    }
+
     // Invoked by descendant columns at a special time during rendering
     internal void AddColumn(ColumnBase<TGridItem> column, SortDirection? initialSortDirection, bool isDefaultSortColumn)
     {