问如何创建自定义Blazor多选择HTML组件？错误: MultipleSelect需要“ValueExpression”参数的值

EN

@using CustomComponents.DataModels
@using System.Linq.Expressions
@using System
@using System.Collections.Generic
@inherits InputBase<string>

<div class="row">
    <div class="col-3">
        <select id="@Id" @bind=@CurrentValue class="form-control @CssClass" multiple="multiple" size="@BoxHieght" style="width:@BoxWidth">
            @foreach (var option in Options)
            {
                <option @onclick="@(() => SelectOption(option))" value="@option.Value">@option.Text</option>
            }
        </select>
    </div>
</div>

@code {
    [Parameter]
    public string Id { get; set; }
    [Parameter]
    public List<Option> Options { get; set; } = new List<Option>();
    [Parameter]
    public Option SelectedOption { get; set; } = new Option { Text = " ", Value = " " };
    [Parameter]
    public int BoxHieght { get; set; } = 5;
    [Parameter]
    public string BoxWidth { get; set; } = "auto";
    [Parameter, EditorRequired]
    public Expression<Func<string>> ValidationFor { get; set; } = default!;

    private void SelectOption(Option option)
    {
        SelectedOption = option;
    }
    protected override bool TryParseValueFromString(string value, out string result, out string validationErrorMessage)
    {
        try
        {
            result = value;
            validationErrorMessage = null;
            return true;
        }
        catch (Exception exception)
        {
            result = null;
            validationErrorMessage = exception.Message;
            return false;
        }

    }    
}

namespace CustomComponents.DataModels
{
    public class Option
    {
        public string Text { get; set; }
        public string Value { get; set; }
    }
}

using CustomComponents.Data.DataModels;

namespace BlazorApp2.Pages.PageModels
{
    public class FormModel
    {
        public Option Option { get; set; } = new Option();
    }
}

using System.ComponentModel.DataAnnotations;

namespace BlazorApp2.Data.DataModels
{
    public class State
    {
        [Required]
        public string Name { get; set; }
        [Required]
        public string Abbreviation { get; set; }
    }
}

@page "/"
@using CustomComponents.Components
@using CustomComponents.Data.DataModels
@using CustomComponents.Pages.PageModels
<PageTitle>Mutiple Select Component</PageTitle>

<EditForm Model="@model" OnValidSubmit="ValidSubmit">  
<DataAnnotationsValidator /> 
<ValidationSummary />
<MyComponent Options="@options" @bind-Value="@model.Option" ValidationFor="() => State.Name"></MyComponent>
Selected option:
<div class="row">
    <div class="col">
        @model.Option.Value  @model.Option.Text
    </div>

</div>
<div class="row">
    <div class="col">
        <button class="btn btn-primary" type="submit">Submit</button>
    </div>
</div>
<div class="row">
    <div class="col">
        @if (formSubmitted) @FormSubmitted
    </div>
</div>
<div class="row">
    <div class="col">
        @if (formSubmitted) @StateSubmitted
    </div>
</div>
</EditForm>

    @code {
    private List<Option> options = new List<Option>();
    public FormModel model = new FormModel();
    public State State { get; set; } = new State();
    private List<State> states = new List<State>
    {
        new State { Name = "Utah", Abbreviation = "UT" },
        new State { Name = "Texas", Abbreviation = "TX" },
        new State { Name = "Florida", Abbreviation = "FL" }
    };
    public string FormSubmitted { get; set; } = "Form submitted.";
    public string StateSubmitted { get; set; } = string.Empty;
    private bool formSubmitted = false;

    protected override void OnInitialized()
    {
        foreach(State state in states)
        {
            options.Add(new Option{ Value = state.Abbreviation, Text = state.Name});
        }
        model.Option = options[0];
    }

    public void ValidSubmit()
    {
        State.Abbreviation = model.Option.Value;
        State.Name = model.Option.Text;
        formSubmitted = true;
        StateSubmitted = $"{State.Abbreviation}  {State.Name}";
    }
}