Add ValueLoaded callback to LazyValue, Fix issues with Typeahead

Author: pwelter34

src/LoreSoft.Blazor.Controls/Lazy/LazyValue.cs

@@ -47,6 +47,12 @@ public class LazyValue<TKey, TValue> : ComponentBase
     [Parameter]
     public string? LoadingText { get; set; }
 
+    /// <summary>
+    /// Gets or sets the callback invoked when the value has been successfully loaded.
+    /// </summary>
+    [Parameter]
+    public EventCallback<TValue?> ValueLoaded { get; set; }
+
     /// <summary>
     /// Gets or sets the loaded value.
     /// </summary>
@@ -74,6 +80,8 @@ protected override async Task OnParametersSetAsync()
             // load the value async
             Value = await LoadMethod(Key);
             _previousKey = Key;
+
+            await ValueLoaded.InvokeAsync(Value);
         }
         finally
         {

src/LoreSoft.Blazor.Controls/Typeahead/Typeahead.razor

@@ -168,7 +168,8 @@
                            TValue="TItem"
                            Key="@value"
                            LoadingText="Loading..."
-                           LoadMethod="@LookupMethod" />
+                           LoadMethod="@LookupMethod"
+                           ValueLoaded="@OnValueLoaded" />
             }
             else if (value == null)
             {

src/LoreSoft.Blazor.Controls/Typeahead/Typeahead.razor.cs

@@ -24,6 +24,8 @@ public partial class Typeahead<TItem, TValue> : StandardComponent
 {
     private readonly DebounceAction<string?> _debouncer = new();
     private readonly LoadingState _loadingState = new();
+    private bool _suppressValueLoadedEvent;
+    private bool _previousDisabled = true;
 
     /// <summary>
     /// Gets or sets the cascading <see cref="EditContext"/> for form validation.
@@ -268,20 +270,17 @@ protected override void OnParametersSet()
                 .AddStyle(MenuStyle)
                 .ToString();
         });
-    }
 
-    /// <inheritdoc />
-    protected override async Task OnInitializedAsync()
-    {
-        await base.OnInitializedAsync();
-
-        // load items if an item loader is provided
-        // will overwrite Items parameter if both are set
-        if (!Disabled && ItemLoader != null)
+        // load items when component transitions from disabled to enabled
+        if (_previousDisabled && !Disabled && ItemLoader != null && CurrentItems.Count == 0)
             ExecuteAfterRender(LoadItems);
+
+        _previousDisabled = Disabled;
     }
 
 
+
+
     /// <summary>
     /// Performs a search using the current search text and updates the search results.
     /// </summary>
@@ -353,6 +352,7 @@ public async Task SelectResult(TItem item)
             {
                 valueList.Add(value);
                 await ValuesChanged.InvokeAsync(valueList);
+                _suppressValueLoadedEvent = true;
                 await SelectionAdded.InvokeAsync(item);
             }
             else
@@ -364,6 +364,7 @@ public async Task SelectResult(TItem item)
         else
         {
             await ValueChanged.InvokeAsync(value);
+            _suppressValueLoadedEvent = true;
             await SelectionAdded.InvokeAsync(item);
         }
 
@@ -606,6 +607,24 @@ private void MoveSelection(int count)
         SelectedIndex = index;
     }
 
+    /// <summary>
+    /// Handles the <see cref="LazyValue{TKey, TValue}.ValueLoaded"/> callback,
+    /// forwarding to <see cref="SelectionAdded"/> unless the event was already
+    /// raised by <see cref="SelectResult"/>.
+    /// </summary>
+    /// <param name="item">The item resolved by the lazy loader.</param>
+    private async Task OnValueLoaded(TItem? item)
+    {
+        if (_suppressValueLoadedEvent)
+        {
+            _suppressValueLoadedEvent = false;
+            return;
+        }
+
+        if (item is not null)
+            await SelectionAdded.InvokeAsync(item);
+    }
+
     /// <summary>
     /// Converts an item to its corresponding value using <see cref="ConvertMethod"/> or direct casting.
     /// </summary>

test/LoreSoft.Blazor.Controls.Tests/Lazy/LazyValueTests.cs

@@ -460,4 +460,58 @@ public void Loading_Property_Is_False_After_Completion()
             Assert.NotNull(cut.Instance.Value);
         });
     }
+
+    [Fact]
+    public void Invokes_ValueLoaded_After_Successful_Load()
+    {
+        // arrange
+        var fruit = Fruit.Data().First();
+        var key = fruit.Id;
+        var loadMethod = Fruit.GetByIdAsync;
+        Fruit? loadedValue = null;
+
+        // act
+        var cut = Render<LazyValue<Guid, Fruit>>(parameters => parameters
+            .Add(p => p.LoadMethod, loadMethod)
+            .Add(p => p.Key, key)
+            .Add(p => p.ValueLoaded, value => loadedValue = value)
+        );
+
+        // assert
+        cut.WaitForAssertion(() =>
+        {
+            Assert.NotNull(loadedValue);
+            Assert.Equal(fruit.Id, loadedValue.Id);
+        });
+    }
+
+    [Fact]
+    public void Invokes_ValueLoaded_On_Key_Change()
+    {
+        // arrange
+        var fruits = Fruit.Data().Take(2).ToArray();
+        var loadMethod = Fruit.GetByIdAsync;
+        var loadedValues = new List<Fruit?>();
+
+        // act
+        var cut = Render<LazyValue<Guid, Fruit>>(parameters => parameters
+            .Add(p => p.LoadMethod, loadMethod)
+            .Add(p => p.Key, fruits[0].Id)
+            .Add(p => p.ValueLoaded, value => loadedValues.Add(value))
+        );
+
+        cut.WaitForAssertion(() => Assert.Single(loadedValues));
+
+        // change key
+        cut.Render(parameters => parameters
+            .Add(p => p.Key, fruits[1].Id)
+        );
+
+        // assert both values were loaded
+        cut.WaitForAssertion(() =>
+        {
+            Assert.Equal(2, loadedValues.Count);
+            Assert.Equal(fruits[1].Id, loadedValues[1]!.Id);
+        });
+    }
 }

test/LoreSoft.Blazor.Controls.Tests/Snapshots/PublicApiTest.PublicApiHasNotChanged.verified.txt

@@ -985,6 +985,8 @@ namespace LoreSoft.Blazor.Controls
         [Microsoft.AspNetCore.Components.Parameter]
         public string? LoadingText { get; set; }
         public TValue Value { get; set; }
+        [Microsoft.AspNetCore.Components.Parameter]
+        public Microsoft.AspNetCore.Components.EventCallback<TValue?> ValueLoaded { get; set; }
         protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder builder) { }
         protected override System.Threading.Tasks.Task OnParametersSetAsync() { }
     }
@@ -1674,7 +1676,6 @@ namespace LoreSoft.Blazor.Controls
         protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder @__builder) { }
         public System.Threading.Tasks.Task Clear() { }
         public void CloseMenu() { }
-        protected override System.Threading.Tasks.Task OnInitializedAsync() { }
         protected override void OnParametersSet() { }
         public System.Threading.Tasks.Task RemoveValue(TValue item) { }
         public System.Threading.Tasks.Task Search(string? searchText) { }