Autocomplete: Add MoreItemsTemplate RenderFragment. (MudBlazor#4566)

* Autocomplete: Add MoreItemsTemplate RenderFragment.

* Fix unit test.

* Always count returned items on search.

src/MudBlazor.UnitTests.Viewer/TestComponents/Autocomplete/AutocompleteTest6.razor

@@ -0,0 +1,43 @@
+@namespace MudBlazor.UnitTests.TestComponents
+<MudPopoverProvider></MudPopoverProvider>
+
+<MudAutocomplete T="string" Label="US States" @bind-Value="value1" SearchFunc="@Search1" MaxItems="10">
+    <MoreItemsTemplate>
+        <MudText>Not all items are shown</MudText>
+    </MoreItemsTemplate>
+</MudAutocomplete>
+
+@code {
+    public static string __description__ = "There are more than 10 items, so the more items template should render";
+
+    private string value1;
+
+    private string[] states =
+    {
+        "Alabama", "Alaska", "American Samoa", "Arizona",
+        "Arkansas", "California", "Colorado", "Connecticut",
+        "Delaware", "District of Columbia", "Federated States of Micronesia",
+        "Florida", "Georgia", "Guam", "Hawaii", "Idaho",
+        "Illinois", "Indiana", "Iowa", "Kansas", "Kentucky",
+        "Louisiana", "Maine", "Marshall Islands", "Maryland",
+        "Massachusetts", "Michigan", "Minnesota", "Mississippi",
+        "Missouri", "Montana", "Nebraska", "Nevada",
+        "New Hampshire", "New Jersey", "New Mexico", "New York",
+        "North Carolina", "North Dakota", "Northern Mariana Islands", "Ohio",
+        "Oklahoma", "Oregon", "Palau", "Pennsylvania", "Puerto Rico",
+        "Rhode Island", "South Carolina", "South Dakota", "Tennessee",
+        "Texas", "Utah", "Vermont", "Virgin Island", "Virginia",
+        "Washington", "West Virginia", "Wisconsin", "Wyoming",
+    };
+
+    private async Task<IEnumerable<string>> Search1(string value)
+    {
+        // In real life use an asynchronous function for fetching data from an api.
+        await Task.Delay(5);
+
+        // if text is null or empty, show complete list
+        if (string.IsNullOrEmpty(value))
+            return states;
+        return states.Where(x => x.Contains(value, StringComparison.InvariantCultureIgnoreCase));
+    }
+}

src/MudBlazor.UnitTests/Components/AutocompleteTests.cs

@@ -221,6 +221,22 @@ public async Task Autocomplete_ReadOnly_Should_Not_Open()
             comp.WaitForAssertion(() => comp.FindAll("div.mud-popover-open").Count.Should().Be(0));
         }
 
+        /// <summary>
+        /// MoreItemsTemplate should render when there are more items than the MaxItems limit
+        /// </summary>
+        [Test]
+        public async Task AutocompleteTest6()
+        {
+            var comp = Context.RenderComponent<AutocompleteTest6>();
+
+            var inputControl = comp.Find("div.mud-input-control");
+            inputControl.Click();
+            comp.WaitForAssertion(() => comp.Find("div.mud-popover").ClassList.Should().Contain("mud-popover-open"));
+
+            var mudText = comp.FindAll("p.mud-typography");
+            mudText[mudText.Count - 1].InnerHtml.Should().Contain("Not all items are shown"); //ensure the text is shown
+        }
+
         /// <summary>
         /// After press Enter key down, the selected value should be shown in the input value
         /// </summary>
@@ -655,7 +671,8 @@ public async Task Autocomplete_Should_Not_Select_Disabled_Item()
         [Test]
         public async Task Autocomplete_ChangeBoundValue()
         {
-            await ImproveChanceOfSuccess(async () => { 
+            await ImproveChanceOfSuccess(async () =>
+            {
                 var comp = Context.RenderComponent<AutocompleteChangeBoundObjectTest>();
                 var autocompletecomp = comp.FindComponent<MudAutocomplete<string>>();
                 var autocomplete = autocompletecomp.Instance;

src/MudBlazor/Components/Autocomplete/MudAutocomplete.razor

@@ -9,7 +9,7 @@
             <InputContent>
                 <MudInput @ref="_elementReference" @key="_elementKey" InputType="InputType.Text"
                           Class="mud-select-input" Margin="@Margin"
-                          Variant="@Variant" 
+                          Variant="@Variant"
                           TextUpdateSuppression="@TextUpdateSuppression"
                           Value="@Text" DisableUnderLine="@DisableUnderLine"
                           Disabled="@Disabled" ReadOnly="@ReadOnly" Error="@Error"
@@ -53,6 +53,12 @@
                                     }
                                 </MudListItem>
                             }
+                            @if (MoreItemsTemplate != null && _itemsReturned > MaxItems)
+                            {
+                                <div class="pa-1">
+                                    @MoreItemsTemplate
+                                </div>
+                            }
                         </MudList>
                     }
                 </MudPopover>

src/MudBlazor/Components/Autocomplete/MudAutocomplete.razor.cs

@@ -183,6 +183,13 @@ public bool Dense
         [Category(CategoryTypes.FormComponent.ListBehavior)]
         public RenderFragment<T> ItemDisabledTemplate { get; set; }
 
+        /// <summary>
+        /// Optional template when more items were returned from the Search function than the MaxItems limit
+        /// </summary>
+        [Parameter]
+        [Category(CategoryTypes.FormComponent.ListBehavior)]
+        public RenderFragment MoreItemsTemplate { get; set; }
+
         /// <summary>
         /// On drop-down close override Text with selected Value. This makes it clear to the user
         /// which list value is currently selected and disallows incomplete values in Text.
@@ -356,6 +363,8 @@ protected override async Task UpdateValuePropertyAsync(bool updateText)
 
         private void OnTimerComplete(object stateInfo) => InvokeAsync(OnSearchAsync);
 
+        private int _itemsReturned; //the number of items returned by the search function
+
         /// <remarks>
         /// This async method needs to return a task and be awaited in order for
         /// unit tests that trigger this method to work correctly.
@@ -378,8 +387,11 @@ private async Task OnSearchAsync()
             {
                 Console.WriteLine("The search function failed to return results: " + e.Message);
             }
+            _itemsReturned = searched_items.Count();
             if (MaxItems.HasValue)
+            {
                 searched_items = searched_items.Take(MaxItems.Value);
+            }
             _items = searched_items.ToArray();
 
             _enabledItemIndices = _items.Select((item, idx) => (item, idx)).Where(tuple => ItemDisabledFunc?.Invoke(tuple.item) != true).Select(tuple => tuple.idx).ToList();