feat(TreeView): add keep toggle/check state function

src/BootstrapBlazor.Server/Components/Samples/TreeViews.razor

@@ -37,15 +37,15 @@
     <section ignore>
         <div>@((MarkupString)Localizer["TreeViewCheckboxTips1"].Value)</div>
         <div>@((MarkupString)Localizer["TreeViewCheckboxTips2"].Value)</div>
-    </section>
-    <section ignore class="row form-inline">
-        <div class="col-12 col-lg-auto">
-            <Checkbox DisplayText="@Localizer["TreeViewCheckboxCheckBoxDisplayText1"]" ShowAfterLabel="true" @bind-Value="@AutoCheckChildren"></Checkbox>
-            <Checkbox DisplayText="@Localizer["TreeViewCheckboxCheckBoxDisplayText2"]" ShowAfterLabel="true" @bind-Value="@AutoCheckParent" class="ms-3"></Checkbox>
-        </div>
-        <div class="col-12 col-lg-auto">
-            <Button Text="@Localizer["TreeViewCheckboxButtonText"]" OnClick="@OnRefresh"></Button>
-            <Button Text="@Localizer["TreeViewCheckboxAddButtonText"]" OnClick="OnClickAddNode" class="ms-3"></Button>
+        <div class="row form-inline">
+            <div class="col-12 col-lg-auto">
+                <Checkbox DisplayText="@Localizer["TreeViewCheckboxCheckBoxDisplayText1"]" ShowAfterLabel="true" @bind-Value="@AutoCheckChildren"></Checkbox>
+                <Checkbox DisplayText="@Localizer["TreeViewCheckboxCheckBoxDisplayText2"]" ShowAfterLabel="true" @bind-Value="@AutoCheckParent" class="ms-3"></Checkbox>
+            </div>
+            <div class="col-12 col-lg-auto">
+                <Button Text="@Localizer["TreeViewCheckboxButtonText"]" OnClick="@OnRefresh"></Button>
+                <Button Text="@Localizer["TreeViewCheckboxAddButtonText"]" OnClick="OnClickAddNode" class="ms-3"></Button>
+            </div>
         </div>
     </section>
     <TreeView Items="@CheckedItems" ShowCheckbox="true" OnTreeItemChecked="@OnTreeItemChecked" AutoCheckChildren="@AutoCheckChildren" AutoCheckParent="@AutoCheckParent"></TreeView>

src/BootstrapBlazor/BootstrapBlazor.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Razor">
 
   <PropertyGroup>
-    <Version>9.3.1-beta11</Version>
+    <Version>9.3.1-beta16</Version>
   </PropertyGroup>
 
   <ItemGroup>

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

@@ -316,6 +316,8 @@ public partial class TreeView<TItem> : IModelEqualityComparer<TItem>
 
     private string? EnableKeyboardString => EnableKeyboard ? "true" : null;
 
+    private bool _shouldRender = true;
+
     private static string? GetItemTextClassString(TreeViewItem<TItem> item) => CssBuilder.Default("tree-node-text")
         .AddClass(item.CssClass)
         .Build();
@@ -355,13 +357,15 @@ protected override void OnParametersSet()
     protected override async Task OnParametersSetAsync()
     {
         _rows = null;
-        TreeNodeStateCache.Reset();
-
         if (Items != null)
         {
             if (Items.Count > 0)
             {
+                _shouldRender = false;
                 await CheckExpand(Items);
+                _shouldRender = true;
+
+                _rows = null;
             }
 
             if (ShowCheckbox && (AutoCheckParent || AutoCheckChildren))
@@ -402,6 +406,12 @@ protected override async Task OnAfterRenderAsync(bool firstRender)
         }
     }
 
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    /// <returns></returns>
+    protected override bool ShouldRender() => _shouldRender;
+
     /// <summary>
     /// <inheritdoc/>
     /// </summary>

src/BootstrapBlazor/Misc/ExpandableNodeCache.cs

@@ -99,7 +99,7 @@ public async Task CheckExpandAsync(TNode node, Func<TNode, Task<IEnumerable<IExp
             if (ExpandedNodeCache.Contains(node.Value))
             {
                 // 原来是展开状态，
-                if (node.HasChildren)
+                if (node.HasChildren || node.Items.Any())
                 {
                     // 当前节点有子节点
                     node.IsExpand = true;

test/UnitTest/Components/TreeViewTest.cs

@@ -363,6 +363,80 @@ public async Task OnExpandRowAsync_Ok()
         Assert.True(expanded);
     }
 
+    [Fact]
+    public async Task KeepExpandState_Ok()
+    {
+        // UI 重新刷新后保持状态节点状态
+        var items = TreeFoo.GetTreeItems();
+        items.RemoveAt(1);
+        items.RemoveAt(1);
+        items[0].HasChildren = true;
+
+        var cut = Context.RenderComponent<TreeView<TreeFoo>>(pb =>
+        {
+            pb.Add(a => a.Items, items);
+            pb.Add(a => a.OnExpandNodeAsync, item =>
+            {
+                return OnExpandNodeAsync(item.Value);
+            });
+        });
+        var nodes = cut.FindAll(".tree-node");
+        Assert.Single(nodes);
+
+        // 展开节点
+        var bar = cut.Find(".fa-caret-right.visible");
+        await cut.InvokeAsync(() => bar.Click());
+
+        cut.WaitForAssertion(() =>
+        {
+            nodes = cut.FindAll(".tree-node");
+            Assert.Equal(3, nodes.Count);
+        });
+
+        // 重新渲染
+        items = TreeFoo.GetTreeItems();
+        items.RemoveAt(1);
+        items.RemoveAt(1);
+        items[0].HasChildren = true;
+        cut.SetParametersAndRender(pb =>
+        {
+            pb.Add(a => a.Items, items);
+        });
+
+        cut.WaitForAssertion(() =>
+        {
+            nodes = cut.FindAll(".tree-node");
+            Assert.Equal(3, nodes.Count);
+        });
+
+        // 重新渲染
+        items = TreeFoo.GetTreeItems();
+        items.RemoveAt(1);
+        items.RemoveAt(1);
+        items[0].HasChildren = false;
+        items[0].Items =
+        [
+            new(new TreeFoo() { Id = "101", ParentId = "1010" })
+            {
+                Text = "懒加载子节点11",
+                HasChildren = true
+            },
+            new(new TreeFoo(){ Id = "102", ParentId = "1010" })
+            {
+                Text = "懒加载子节点22"
+            }
+        ];
+        cut.SetParametersAndRender(pb =>
+        {
+            pb.Add(a => a.Items, items);
+        });
+        cut.WaitForAssertion(() =>
+        {
+            nodes = cut.FindAll(".tree-node");
+            Assert.Equal(3, nodes.Count);
+        });
+    }
+
     [Fact]
     public async Task OnExpandRowAsync_CheckCascadeState_Ok()
     {