I am Working On A Blazor 8 Project . I am Unable get the Courses (on the basis of Specialization Id) In Course Select Element and also As With @bind cannot use @onChange Event Together

HandleSpecilaizationOnChangeEvent Not Getting Called in this way. but With @onchange it is working..

below Is the Code Please Help.

Child Component

<section>
    <div class="row">
        <div class="col-4">
            <label>Name</label>
            <input class="form-control" type="text" @bind="Model.Name" />
        </div>

        <div class="col-4">
            <label>Gender</label>
            <select class="form-control" @bind="Model.Gender">
                <option value="0">Select</option>
                @foreach (var gender in Genders)
                {
                    <option value="@gender">@gender</option>
                }
            </select>
        </div>

        <div class="col-4">
            <label>Age</label>
            <input class="form-control" type="number" @bind="Model.Age" />
        </div>


        <div class="col-4">
            <label>Contact No</label>
            <input class="form-control" type="text" @bind="Model.ContactNo" />
        </div>

        <div class="col-4">
            <label>Specialization </label>
            <select class="form-control" @bind="Model.Specialisation">
                <option value="0">Select</option>
                @foreach (var Specialization in Specializations)
                {
                    <option value="@Specialization.Key">@Specialization.Value</option>
                }
            </select>
        </div>

        <div class="col-4">
            <label>Course</label>
            <select class="form-control" @bind="Model.Course">
                <option value="0">Select</option>
                @if (Courses != null)
                {
                    @foreach (var course in Courses)
                    {
                        <option value="@course.Key">@course.Value</option>
                    }
                }
            </select>
        </div>
    </div>
    @if (Id == null)
    {
        <div class="row mt-5">
            <div class="col-6">
                <button type="submit" @onclick="HandleSave" class="btn btn-outline-primary">Save</button>
            </div>

        </div>
    }
    else
    {
        <div class="row mt-5">
            <div class="col-6">
                <button type="submit" class="btn btn-outline-warning">Update</button>
            </div>

        </div>
    }

</section>

@code {

    [Parameter] public StudentModel Model { get; set; } = new StudentModel();
    [Parameter] public string? Id { get; set; }
    [Parameter] public List<string> Genders { get; set; } = [];
    [Parameter] public Dictionary<int, string> Specializations { get; set; } = [];
    [Parameter] public Dictionary<int, string> Courses { get; set; } = [];
    [Parameter] public EventCallback OnSpecialisationChangeEvent { get; set; }
    [Parameter] public EventCallback OnHandleSave{ get; set; }


    public async Task HandleSpecilaizationOnChangeEvent(ChangeEventArgs value)
    {
        Model.Specialisation =value!.ToString()!;
        await OnSpecialisationChangeEvent.InvokeAsync(Model.Specialisation);
    }

    public async Task HandleSave()
    {
        await OnHandleSave.InvokeAsync();
    }
}

Parent Component

@page "/Add"
@page "/Add/{Id}"
@using BlazorApp1.Models
@using BlazorApp1.Services
@rendermode InteractiveServer
@inject IStudentService service

<section class="container">

    @if (Id == null)
    {
        <span>Add Student Record</span>
    }
    else
    {
        <span>Edit Student Record</span>
    }
    <UserForm Model="StudentModel" Id="@Id" Genders="@Genders"
              Specializations="@Specializations" OnSpecialisationChangeEvent="@HandleSpecializationChangeEvent"
              Courses="@Courses" OnHandleSave="@HandleValidSubmit"  />

</section>

@code {

    [Parameter] public string? Id { get; set; }
    private StudentModel StudentModel { get; set; } = new StudentModel();
    private List<string> Genders = [];
    private Dictionary<int, string> Specializations = [];
    private Dictionary<int, string> Courses = [];

    protected override async Task OnInitializedAsync()
    {
        Genders = await service.GetGenders();
        Specializations = await service.GetSpecialisations();

        if (Id is not null)
        {
            StudentModel = await service.FetchStudentDetails(int.Parse(Id));
            await HandleSpecializationChangeEvent(Id);
        }

    }

    private async Task HandleSpecializationChangeEvent(Object e)
    {
        if (e is ChangeEventArgs changeEventArgs)
        {
            string selectedValue = changeEventArgs.Value?.ToString()!;
            if (!string.IsNullOrEmpty(selectedValue))
            {
                if (int.TryParse(selectedValue, out int SpecializationId))
                {
                    if (SpecializationId != 0)
                    {
                        Courses = await service.GetCourses(SpecializationId);
                    }
                    else
                    {
                        Courses.Clear();
                    }
                }
            }
        }
        else
        {
            Courses = await service.GetCourses(int.Parse(e.ToString()!));
        }
    }

    private async Task HandleValidSubmit()
    {
        var res = await service.SaveCourseDetails(StudentModel);
    }

}

 public class StudentModel
 {
     public int Id { get; set; } 
     [Required] public string Name { get; set; } = string.Empty;
     [Required] public int Age { get; set; } 
     [Required] public int ContactNo { get; set; }
     [Required] public string Gender { get; set; } = "0";
     [Required] public string Specialisation { get; set; } = "0";
     [Required] public string Course { get; set; } = "0";
 }

there are two scenarios Direct Add(Problem) and Edit Mode (Working Fine)

On Direct Mode , When I change the Specialization , its relevant data Should be Populated On Course Select List..

also I My OnInitializedAsync Methods Runs Two Times .

Please Help.