BlazorEditForms/CustomFluentValidator.cs

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Forms;

namespace BlazorEditForms;

public class CustomFluentValidator : ComponentBase, IDisposable
{
    private IDisposable? _subscriptions;
    private EditContext? _originalEditContext;

    [CascadingParameter] EditContext? CurrentEditContext { get; set; }
    [Inject] private IServiceProvider ServiceProvider { get; set; } = default!;

    protected override void OnInitialized()
    {
        if (CurrentEditContext == null)
        {
            throw new InvalidOperationException($"{nameof(DataAnnotationsValidator)} requires a cascading " +
                                                $"parameter of type {nameof(EditContext)}. For example, you can use {nameof(DataAnnotationsValidator)} " +
                                                $"inside an EditForm.");
        }

        _subscriptions = new CustomFluentValidationManager(CurrentEditContext, ServiceProvider);
        _originalEditContext = CurrentEditContext;
    }

    protected override void OnParametersSet()
    {
        if (CurrentEditContext != _originalEditContext)
        {
            // While we could support this, there's no known use case presently. Since InputBase doesn't support it,
            // it's more understandable to have the same restriction.
            throw new InvalidOperationException($"{GetType()} does not support changing the " +
                                                $"{nameof(EditContext)} dynamically.");
        }
    }

    public void Dispose()
    {
        _subscriptions?.Dispose();
        _subscriptions = null;
    }
}