Adds async auto validation to FluentValidation

fluent-async-autovalidation.cs

using System;
using System.Threading.Tasks;
using FluentValidation;
using FluentValidation.AspNetCore;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.AspNetCore.Mvc.ModelBinding;

namespace Actions
{
    public class AsyncAutoValidation : IAsyncActionFilter
    {
        public static int OrderLowerThanModelStateInvalidFilter => -2001;

        private readonly IServiceProvider serviceProvider;
        public AsyncAutoValidation(IServiceProvider serviceProvider)
        {
            this.serviceProvider = serviceProvider;
        }
        public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
        {
            foreach (var parameter in context.ActionDescriptor.Parameters)
            {
                if ((parameter.BindingInfo.BindingSource == BindingSource.Body
                     || parameter.BindingInfo.BindingSource == BindingSource.Query
                         && parameter.ParameterType.IsClass)
                    && serviceProvider.GetService(typeof(IValidator<>).MakeGenericType(parameter.ParameterType)) is IValidator validator)
                {
                    var subject = context.ActionArguments[parameter.Name];
                    var result = await validator.ValidateAsync(new ValidationContext<object>(subject), context.HttpContext.RequestAborted);
                    if (!result.IsValid)
                    {
                        result.AddToModelState(context.ModelState, null);
                    }
                }
            }
            await next();
        }
    }
}

program.cs

builder.Services.AddControllers().AddFluentValidationAsyncAutoValidation();

servicecollectionextensions.cs

using Microsoft.Extensions.DependencyInjection;

namespace Extensions
{
    public static class ServiceCollectionExtensions
    {
        public static IMvcBuilder AddFluentValidationAsyncAutoValidation(this IMvcBuilder builder)
        {
            return builder.AddMvcOptions(o =>
            {
                o.Filters.Add<AsyncAutoValidation>(AsyncAutoValidation.OrderLowerThanModelStateInvalidFilter);
            });
        }
    }
}