12. Validate DTO Using Data Annotations | Required, Nullable, Optional Fields (.NET 9)

Welcome back to Code Nest Code Nest Institute!
In the previous video, we tested all CRUD operations using Postman.

In this video, we will add Data Annotation Validation to our DTOs inside the Application Layer.

What You Will Learn

✔ What is Data Annotation?
✔ [Required] attribute and how validation works
✔ How ASP.NET Core returns validation errors
✔ Making fields optional using nullable ?
✔ Why description should allow null values
✔ Testing validation errors in Postman
✔ How ASP.NET Core automatically validates DTOs
✔ How to fix unexpected validation messages

We will test different scenarios:

Empty JSON request
Missing required fields
Passing only one field
Passing all required fields
Allowing optional fields (Description)

This helps ensure your API rejects invalid requests before they reach your handlers or database.

In the next video, we will learn how to create unique field validation using database constraints and EF Core.

Stay connected and keep learning!

#dotnet9 #DataAnnotations #Validation #aspnetcore #CleanArchitecture #csharp #WebAPI #EFCore #BackendDevelopment #Programming #CodeNestAcademy

Видео 12. Validate DTO Using Data Annotations | Required, Nullable, Optional Fields (.NET 9) канала Code Nest