{Combobox] Fix loop when changing value (#3300)

* Fix #3297
ListComponentBase:
- Add a backing field for InternalValue
- Refine checks in OnParameterSet
- Use check on initialized parameters like FluentInputBase

FluentCobobox:
- Use check on initialized parameters like FluentInputBase
- Invoke SelectedOptionChanged if selectedOption is set to null

* Fix test

examples/Demo/Shared/Pages/Lab/IssueTester.razor

@@ -1 +1,76 @@
-
+@page "/FluentComboBox"
+
+@using System.Linq.Expressions
+
+<Form Model="modelTest" EnableFluentValidation=true>
+    <FluentCombobox
+    SelectedOptionChanged="@((selectedOption) => OnSelectedOptionChangedAsync(selectedOption))"
+    ValueChanged="@((value) => OnValueChangedAsync(value))"
+    ValueExpression="@(() => modelTest.SelectedValue)"
+    TOption="OptionItem"
+    Items="@Items"
+    OptionValue="@(i => i.Value)"
+    OptionText="@(i => i.Name)"
+    OptionDisabled="@(i => i.Disabled)"
+    OptionSelected="@(i => i.Value == modelTest.SelectedValue)"
+    Autocomplete=ComboboxAutocomplete.Both
+    Placeholder="Testing binding" />
+
+    <p>@modelTest.SelectedValue</p>
+    <p>@typedText</p>
+</Form>
+
+@code {
+    private string? typedText;
+    private OptionItem[] Items { get; set; } = [
+        new OptionItem { Name = "Test 1", Value = "TEST1", Disabled = false },
+        new OptionItem { Name = "Test 2", Value = "TEST2", Disabled = false },
+        new OptionItem { Name = "Test 3", Value = "TEST3", Disabled = false }
+    ];
+
+    public class ModelTest
+    {
+        public string? SelectedValue { get; set; }
+    }
+
+    private ModelTest modelTest = new();
+
+    private async Task OnSelectedOptionChangedAsync(OptionItem? selectedOption)
+    {
+        if (selectedOption is not null)
+        {
+            Console.WriteLine($"OnSelectedOptionChangedAsync enter modelTest.SelectedValue:{modelTest.SelectedValue}, selectedOption.Value:{selectedOption.Value}.");
+            if (modelTest.SelectedValue != selectedOption.Value)
+            {
+                Console.WriteLine($"OnSelectedOptionChangedAsync before modelTest.SelectedValue:{modelTest.SelectedValue}, selectedOption.Value:{selectedOption.Value}.");
+                modelTest.SelectedValue = selectedOption.Value;
+                Console.WriteLine($"OnSelectedOptionChangedAsync after modelTest.SelectedValue:{modelTest.SelectedValue}, selectedOption.Value:{selectedOption.Value}.");
+            }
+        }
+
+        await Task.CompletedTask;
+    }
+
+    private async Task OnValueChangedAsync(string? text)
+    {
+        Console.WriteLine($"OnValueChangedAsync enter modelTest.SelectedValue:{modelTest.SelectedValue}, text:{text}.");
+        typedText = text;
+        if (modelTest.SelectedValue != default
+            && (string.IsNullOrEmpty(text) || !Items.Select(i => i.Name).Contains(text)))
+        {
+            Console.WriteLine($"OnValueChangedAsync before value:{modelTest.SelectedValue}");
+            modelTest.SelectedValue = default;
+            Console.WriteLine($"OnValueChangedAsync after value:{modelTest.SelectedValue}");
+        }
+
+        await Task.CompletedTask;
+    }
+
+    public class OptionItem
+    {
+        public string? Name { get; set; }
+        public string? Value { get; set; }
+        public bool Hidden { get; set; }
+        public bool Disabled { get; set; }
+    }
+}

src/Core/Components/List/FluentCombobox.razor.cs

@@ -13,6 +13,7 @@ namespace Microsoft.FluentUI.AspNetCore.Components;
 public partial class FluentCombobox<TOption> : ListComponentBase<TOption>, IAsyncDisposable where TOption : notnull
 {
     private const string JAVASCRIPT_FILE = "./_content/Microsoft.FluentUI.AspNetCore.Components/Components/List/FluentCombobox.razor.js";
+    private bool _hasInitializedParameters;
 
     /// <summary />
     [Inject]
@@ -83,56 +84,61 @@ public override async Task SetParametersAsync(ParameterView parameters)
     {
         parameters.SetParameterProperties(this);
 
-        var isSetSelectedOption = false;
-        TOption? newSelectedOption = default;
-
-        foreach (var parameter in parameters)
+        if (!_hasInitializedParameters)
         {
-            switch (parameter.Name)
+
+            var isSetSelectedOption = false;
+            TOption? newSelectedOption = default;
+
+            foreach (var parameter in parameters)
             {
-                case nameof(SelectedOption):
-                    isSetSelectedOption = true;
-                    newSelectedOption = (TOption?)parameter.Value;
-                    break;
-                default:
-                    break;
+                switch (parameter.Name)
+                {
+                    case nameof(SelectedOption):
+                        isSetSelectedOption = true;
+                        newSelectedOption = (TOption?)parameter.Value;
+                        break;
+                    default:
+                        break;
+                }
             }
-        }
 
-        if (isSetSelectedOption && !Equals(_currentSelectedOption, newSelectedOption))
-        {
-            if (Items != null)
+            if (isSetSelectedOption && !Equals(_currentSelectedOption, newSelectedOption))
             {
-                if (Items.Contains(newSelectedOption))
+                if (Items != null)
                 {
-                    _currentSelectedOption = newSelectedOption;
+                    if (Items.Contains(newSelectedOption))
+                    {
+                        _currentSelectedOption = newSelectedOption;
+                    }
+                    else if (OptionSelected != null && newSelectedOption != null && OptionSelected(newSelectedOption))
+                    {
+                        // The selected option might not be part of the Items list. But we can use OptionSelected to compare the current option.
+                        _currentSelectedOption = newSelectedOption;
+                    }
+                    else
+                    {
+                        // If the selected option is not in the list of items, reset the selected option
+                        _currentSelectedOption = SelectedOption = default;
+                        await SelectedOptionChanged.InvokeAsync(SelectedOption);
+                    }
                 }
-                else if (OptionSelected != null && newSelectedOption != null && OptionSelected(newSelectedOption))
+                else
                 {
-                    // The selected option might not be part of the Items list. But we can use OptionSelected to compare the current option.
+                    // If Items is null, we don't know if the selected option is in the list of items, so we just set it
                     _currentSelectedOption = newSelectedOption;
                 }
-                else
+
+                // Sync Value from selected option.
+                // If it is null, we set it to the default value so the attribute is not deleted & the webcomponents don't throw an exception
+                var value = GetOptionValue(_currentSelectedOption) ?? string.Empty;
+                if (Value != value)
                 {
-                    // If the selected option is not in the list of items, reset the selected option
-                    _currentSelectedOption = SelectedOption = default;
-                    await SelectedOptionChanged.InvokeAsync(SelectedOption);
+                    Value = value;
+                    await ValueChanged.InvokeAsync(Value);
                 }
             }
-            else
-            {
-                // If Items is null, we don't know if the selected option is in the list of items, so we just set it
-                _currentSelectedOption = newSelectedOption;
-            }
-
-            // Sync Value from selected option.
-            // If it is null, we set it to the default value so the attribute is not deleted & the webcomponents don't throw an exception
-            var value = GetOptionValue(_currentSelectedOption) ?? string.Empty;
-            if (Value != value)
-            {
-                Value = value;
-                await ValueChanged.InvokeAsync(Value);
-            }
+            _hasInitializedParameters = true;
         }
 
         await base.SetParametersAsync(ParameterView.Empty);
@@ -144,11 +150,12 @@ protected override async Task ChangeHandlerAsync(ChangeEventArgs e)
         if (e.Value is not null && Items is not null)
         {
             var value = e.Value.ToString();
-            TOption? item = Items.FirstOrDefault(i => GetOptionText(i) == value);
+            var item = Items.FirstOrDefault(i => GetOptionText(i) == value);
 
             if (item is null)
             {
                 SelectedOption = default;
+                await SelectedOptionChanged.InvokeAsync(SelectedOption);
             }
             else
             {