Under Posting Attack in .NET Core

Question

In .NET 6 I have a DTO with value data types like int.

But while sending a POST request if user omits the value for that default value is getting assigned without any Error.

What are the best practices to avoid this under posting?

I have tried using [Required] ,[BindRequired] but still not addressed my concern.

I know we can add some other validation attribute to check if value is not equal to 0. But I want to know how to validate the under posting attack.

Answer 1

Use a nullable int type and check for null.

    public class MyClass
    {
        public int? MyNullableInt { get; set; }
    } 

The official documentation covers model validation.

https://learn.microsoft.com/en-us/aspnet/core/mvc/models/validation?view=aspnetcore-8.0