feat(Textarea): add OnBlurAsync parameter (#4518)

* feat: 增加 OnBlurAsync 回调方法

* test: 更新单元测试

Author: ArgoZhang

src/BootstrapBlazor/Components/Textarea/Textarea.razor

@@ -6,4 +6,4 @@
 {
     <BootstrapLabel required="@Required" for="@Id" ShowLabelTooltip="ShowLabelTooltip" Value="@DisplayText" />
 }
-<textarea @attributes="AdditionalAttributes" placeholder="@PlaceHolder" id="@Id" class="@ClassName" disabled="@Disabled" @bind-value="@CurrentValueAsString" @bind-value:event="@EventString" data-bb-scroll="@AutoScrollString" @ref="FocusElement"></textarea>
+<textarea @attributes="AdditionalAttributes" placeholder="@PlaceHolder" id="@Id" class="@ClassName" disabled="@Disabled" @bind-value="@CurrentValueAsString" @bind-value:event="@EventString" @onblur="OnBlur" data-bb-scroll="@AutoScrollString" @ref="FocusElement"></textarea>

src/BootstrapBlazor/Components/Textarea/Textarea.razor.cs

@@ -34,6 +34,12 @@ public partial class Textarea
     [Parameter]
     public bool IsAutoScroll { get; set; }
 
+    /// <summary>
+    /// 获得/设置 失去焦点回调方法 默认 null
+    /// </summary>
+    [Parameter]
+    public Func<string?, Task>? OnBlurAsync { get; set; }
+
     /// <summary>
     /// 获得 客户端是否自动滚屏标识
     /// </summary>
@@ -53,4 +59,15 @@ protected override async Task OnAfterRenderAsync(bool firstRender)
             await InvokeVoidAsync("execute", Id, "update");
         }
     }
+
+    /// <summary>
+    /// OnBlur 方法
+    /// </summary>
+    protected virtual async Task OnBlur()
+    {
+        if (OnBlurAsync != null)
+        {
+            await OnBlurAsync(Value);
+        }
+    }
 }

test/UnitTest/Components/TextareaTest.cs

@@ -53,4 +53,21 @@ public void AutoScrollString_OK()
         cut.Instance.ScrollToTop();
         cut.Instance.ScrollToBottom();
     }
+
+    [Fact]
+    public async Task OnBlurAsync_Ok()
+    {
+        var blur = false;
+        var cut = Context.RenderComponent<Textarea>(builder =>
+        {
+            builder.Add(a => a.OnBlurAsync, v =>
+            {
+                blur = true;
+                return Task.CompletedTask;
+            });
+        });
+        var input = cut.Find("textarea");
+        await cut.InvokeAsync(() => { input.Blur(); });
+        Assert.True(blur);
+    }
 }