fix(Cascade): display incorrect when set Items async (#6954)

* fix: 修复数据源为 null 时赋值逻辑

* chore: bump version 9.11.3-beta05

* test: 增加单元测试

Author: ArgoZhang

src/BootstrapBlazor/BootstrapBlazor.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Razor">
 
   <PropertyGroup>
-    <Version>9.11.3-beta04</Version>
+    <Version>9.11.3-beta05</Version>
   </PropertyGroup>
 
   <ItemGroup>

src/BootstrapBlazor/Components/Cascader/Cascader.razor.cs

@@ -133,10 +133,16 @@ protected override void OnParametersSet()
         SubMenuIcon ??= IconTheme.GetIconByKey(ComponentIcons.CascaderSubMenuIcon);
         ClearIcon ??= IconTheme.GetIconByKey(ComponentIcons.SelectClearIcon);
 
-        Items ??= [];
-
         PlaceHolder ??= Localizer[nameof(PlaceHolder)];
 
+        Items ??= [];
+        if (!Items.Any())
+        {
+            _lastValue = string.Empty;
+            Value = default;
+            return;
+        }
+
         if (_lastValue != CurrentValueAsString)
         {
             _lastValue = CurrentValueAsString;

test/UnitTest/Components/CascaderTest.cs

@@ -173,7 +173,16 @@ public void SetDefaultValue_Ok()
             pb.Add(a => a.Value, "1");
             pb.Add(a => a.ShowFullLevels, false);
         });
-        Assert.Empty(cut.Instance.Value);
+
+        // 未提供数据源时 Value 赋值无效
+        Assert.Null(cut.Instance.Value);
+
+        cut.SetParametersAndRender(pb =>
+        {
+            pb.Add(a => a.Items, items);
+            pb.Add(a => a.Value, "3");
+            pb.Add(a => a.ShowFullLevels, false);
+        });
     }
 
     [Fact]