chapter-organizer/WebApp/Components/Features/Students/Edit.razor

@page "/students/edit"
@attribute [Authorize]
@using Microsoft.EntityFrameworkCore
@using WebApp.Components.Shared.Components
@using MudBlazor
@using WebApp.Services
@inject AppDbContext Context
@inject NavigationManager NavigationManager
@inject ISnackbar Snackbar
@inject FormValidationService ValidationService

@if (Student is null || _editContext is null)
{
    <p><em>Loading...</em></p>
    return;
}

<PageHeader
    Title="Edit Student"
    Subtitle="@($"{Student.FirstNameLastName}")"
    ShowBackButton="true"
    BackButtonUrl="@(ReturnUrl ?? "/students")" />

@* https://www.mudblazor.com/components/form *@
@* https://medium.com/@husainalbar/applying-mudblazor-for-crud-operations-in-our-blazor-project-a343037a52ef *@
<EditForm method="post" EditContext="@_editContext" OnInvalidSubmit="OnInvalidSubmit" FormName="edit" Enhance>
        <FormChangeTracker @ref="_formChangeTracker" />
        <AntiforgeryToken />
        <DataAnnotationsValidator/>
        
        <ValidationErrorDisplay Errors="_validationErrors" />
        
        <MudGrid>
            <MudItem xs="12" sm="7">
                <MudPaper Elevation="2" Class="pa-3 pa-md-6">
                    <MudTextField T="string" Label="First Name" @bind-Value="Student.FirstName" For="@(() => Student.FirstName)"></MudTextField>
                    <MudTextField T="string" Label="Last Name" @bind-Value="Student.LastName" For="@(() => Student.LastName)"></MudTextField>
                    <MudTextField T="string" Label="Email Adress" @bind-Value="Student.Email" For="@(() => Student.Email)"></MudTextField>
                    <MudTextField T="string" Label="Phone Number" @bind-Value="Student.PhoneNumber" For="@(() => Student.PhoneNumber)"></MudTextField>
                    <MudTextField T="int" Label="Grade" @bind-Value="Student.Grade" For="@(() => Student.Grade)"></MudTextField>
                    <MudTextField T="int" Label="TSA Year" @bind-Value="Student.TsaYear" For="@(() => Student.TsaYear)"></MudTextField>
                    <MudTextField T="string" Label="Regional Id" @bind-Value="Student.RegionalId" For="@(() => Student.RegionalId)"></MudTextField>
                    <MudTextField T="string" Label="State Id" @bind-Value="Student.StateId" For="@(() => Student.StateId)"></MudTextField>
                    <MudTextField T="string" Label="National Id" @bind-Value="Student.NationalId" For="@(() => Student.NationalId)"></MudTextField>
                    <MudSelect T="OfficerRole?" @bind-Value="@Student.OfficerRole" Label="Officer Role">

                        <MudSelectItem T="OfficerRole?" Value="@null">-not an officer-</MudSelectItem>
                        @foreach (var officerRole in Enum.GetValues(typeof(OfficerRole)).Cast<OfficerRole>())
                        {
                            <MudSelectItem T="OfficerRole?" Value="@(officerRole)"></MudSelectItem>
                        }
                    </MudSelect>
                </MudPaper>
            </MudItem>
        </MudGrid>
</EditForm>

<FormActions>
    <MudButton OnClick="UpdateStudent" Variant="Variant.Filled" Color="Color.Primary">Save</MudButton>
    <MudButton OnClick="HandleCancel" Variant="Variant.Text">Cancel</MudButton>
</FormActions>

@code {
    [SupplyParameterFromQuery]
    private int Id { get; set; }

    [SupplyParameterFromQuery]
    private string? ReturnUrl { get; set; }

    [SupplyParameterFromForm]
    private Student? Student { get; set; }

    private FormChangeTracker? _formChangeTracker;
    private EditContext? _editContext;
    private List<string> _validationErrors = new();

    protected override async Task OnInitializedAsync()
    {
        Student ??= await Context.Students.FirstOrDefaultAsync(m => m.Id == Id);

        if (Student is null)
        {
            NavigationManager.NavigateTo("notfound");
        }
        else
        {
            _editContext = new EditContext(Student);
        }
    }

    private void OnInvalidSubmit(EditContext editContext)
    {
        _validationErrors = ValidationService.HandleInvalidSubmit(editContext, Student!, errors => _validationErrors = errors);
        StateHasChanged();
    }

    // To protect from overposting attacks, enable the specific properties you want to bind to.
    // For more information, see https://learn.microsoft.com/aspnet/core/blazor/forms/#mitigate-overposting-attacks.
    private async Task UpdateStudent()
    {
        // Validate before processing
        if (_editContext != null)
        {
            var errors = ValidationService.CollectValidationErrors(_editContext, Student!);
            if (errors.Any())
            {
                _validationErrors = ValidationService.HandleInvalidSubmit(_editContext, Student!, err => _validationErrors = err);
                StateHasChanged();
                return;
            }
        }

        _validationErrors.Clear();

        if (Student?.OfficerRole == 0)
            Student.OfficerRole = null;

        Context.Attach(Student!).State = EntityState.Modified;

        try
        {
            await Context.SaveChangesAsync();
            Snackbar.Add($"Student '{Student!.FirstNameLastName}' saved successfully.", Severity.Success);
            _formChangeTracker?.AllowNavigation();
            NavigationManager.NavigateTo(ReturnUrl ?? "/students");
        }
        catch (DbUpdateConcurrencyException ex)
        {
            if (!ValidationService.HandleDbUpdateConcurrencyException(
                ex,
                () => StudentExists(Student!.Id),
                "student",
                () => NavigationManager.NavigateTo("notfound")))
            {
                throw;
            }
        }
        catch (DbUpdateException ex)
        {
            ValidationService.HandleDbUpdateException(
                ex,
                "An error occurred while saving the student.",
                "student",
                "saving");
        }
        catch (Exception ex)
        {
            ValidationService.HandleException(ex);
        }
    }

    private async Task HandleCancel()
    {
        // Discard all in-memory changes by reloading from database
        if (Student != null)
        {
            await Context.Entry(Student).ReloadAsync();
        }

        _formChangeTracker?.AllowNavigation();
        NavigationManager.NavigateTo(ReturnUrl ?? "/students");
    }

    private bool StudentExists(int id)
    {
        return Context.Students.Any(e => e.Id == id);
    }
}