fix(TreeView): reset Items to null (#4894)

* TreeView 修复 IsReset 为false时，Items变化后无法正常刷新

* refactor: support Items null

* feat: support null items

* test: 增加单元测试

* revert: 撤销代码更改

---------

Co-authored-by: Argo-AsicoTech <[email protected]>

Author: kimdiego2098

src/BootstrapBlazor/Components/TreeView/TreeView.razor

@@ -6,7 +6,11 @@
 
 @if (Items == null)
 {
-    if (ShowSkeleton)
+    if (_init)
+    {
+        
+    }
+    else if (ShowSkeleton)
     {
         <SkeletonTree AdditionalAttributes="AdditionalAttributes"></SkeletonTree>
     }

src/BootstrapBlazor/Components/TreeView/TreeView.razor.cs

@@ -315,6 +315,8 @@ public partial class TreeView<TItem> : IModelEqualityComparer<TItem>
         .AddClass(item.CssClass)
         .Build();
 
+    private bool _init;
+
     /// <summary>
     /// <inheritdoc/>
     /// </summary>
@@ -377,6 +379,13 @@ protected override async Task OnParametersSetAsync()
             // 设置 ActiveItem 默认值
             ActiveItem ??= Items.FirstOrDefaultActiveItem();
             ActiveItem?.SetParentExpand<TreeViewItem<TItem>, TItem>(true);
+            _init = true;
+        }
+        else
+        {
+            _rows = null;
+            TreeNodeStateCache.Reset();
+            ActiveItem = null;
         }
     }
 

test/UnitTest/Components/TreeViewTest.cs

@@ -26,6 +26,13 @@ public void Items_Ok()
             pb.Add(a => a.Items, TreeFoo.GetTreeItems());
         });
         cut.Contains("li");
+
+        cut.SetParametersAndRender(pb =>
+        {
+            pb.Add(a => a.Items, null);
+            pb.Add(a => a.ShowSkeleton, false);
+        });
+        Assert.Equal("", cut.Markup);
     }
 
     [Fact]