feat: add validation behavior

Application/Common/Behaviors/ValidationBehavior.cs

@@ -0,0 +1,30 @@
+using FluentValidation;
+using MediatR;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Mirea.Api.DataAccess.Application.Common.Behaviors;
+
+public class ValidationBehavior<TRequest, TResponse>(IEnumerable<IValidator<TRequest>> validators)
+    : IPipelineBehavior<TRequest, TResponse> where TRequest : IRequest<TResponse>
+{
+    public Task<TResponse> Handle(TRequest request,
+        RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
+    {
+        var context = new ValidationContext<TRequest>(request);
+        var failures = validators
+            .Select(v => v.Validate(context))
+            .SelectMany(result => result.Errors)
+            .Where(failure => failure != null)
+            .ToList();
+
+        if (failures.Count != 0)
+        {
+            throw new ValidationException(failures);
+        }
+
+        return next();
+    }
+}