refactor: 增加内部缓存提高性能

Author: ArgoZhang

src/BootstrapBlazor/Components/Select/MultiSelect.razor

@@ -66,7 +66,7 @@
                 @ButtonTemplate
             </div>
         }
-        @foreach (var itemGroup in GetData().GroupBy(i => i.GroupName))
+        @foreach (var itemGroup in Rows.GroupBy(i => i.GroupName))
         {
             if (!string.IsNullOrEmpty(itemGroup.Key))
             {
@@ -102,7 +102,7 @@
                 </DynamicElement>
             }
         }
-        @if (GetData().Count == 0)
+        @if (Rows.Count == 0)
         {
             <div class="dropdown-item">@NoSearchDataText</div>
         }

src/BootstrapBlazor/Components/Select/MultiSelect.razor.cs

@@ -195,6 +195,17 @@ public partial class MultiSelect<TValue>
     [NotNull]
     private IStringLocalizer<MultiSelect<TValue>>? Localizer { get; set; }
 
+    private List<SelectedItem>? _itemsCache;
+
+    private List<SelectedItem> Rows
+    {
+        get
+        {
+            _itemsCache ??= string.IsNullOrEmpty(SearchText) ? GetRowsByItems() : GetRowsBySearch();
+            return _itemsCache;
+        }
+    }
+
     private string? PreviousValue { get; set; }
 
     private string? PlaceholderString => SelectedItems.Count == 0 ? PlaceHolder : null;
@@ -220,7 +231,6 @@ protected override void OnParametersSet()
         ClearIcon ??= IconTheme.GetIconByKey(ComponentIcons.MultiSelectClearIcon);
 
         ResetItems();
-        OnSearchTextChanged ??= text => Items.Where(i => i.Text.Contains(text, StringComparison.OrdinalIgnoreCase));
         ResetRules();
 
         // 通过 Value 对集合进行赋值
@@ -250,6 +260,26 @@ protected override void OnAfterRender(bool firstRender)
     /// <returns></returns>
     protected override Task InvokeInitAsync() => InvokeVoidAsync("init", Id, Interop, new { ConfirmMethodCallback = nameof(ConfirmSelectedItem), SearchMethodCallback = nameof(TriggerOnSearch), TriggerEditTag = nameof(TriggerEditTag), ToggleRow = nameof(ToggleRow) });
 
+    private List<SelectedItem> GetRowsByItems()
+    {
+        var items = new List<SelectedItem>();
+        if (Items != null)
+        {
+            items.AddRange(Items);
+        }
+        return items;
+    }
+
+    private List<SelectedItem> GetRowsBySearch()
+    {
+        var items = OnSearchTextChanged?.Invoke(SearchText) ?? FilterBySearchText(GetRowsByItems());
+        return items.ToList();
+    }
+
+    private IEnumerable<SelectedItem> FilterBySearchText(IEnumerable<SelectedItem> source) => string.IsNullOrEmpty(SearchText)
+        ? source
+        : source.Where(i => i.Text.Contains(SearchText, StringComparison));
+
     /// <summary>
     /// FormatValueAsString 方法
     /// </summary>
@@ -540,6 +570,7 @@ private void ResetItems()
     [JSInvokable]
     public Task TriggerOnSearch(string searchText)
     {
+        _itemsCache = null;
         SearchText = searchText;
         StateHasChanged();
         return Task.CompletedTask;