Differences in models for GET and POST requests

Question

I am creating a Web API using Asp .NET Core and am having troubles figuring out how to create my data models.

Lets say I get the following model from the backend:

public class Author : AuditEntity
{
    public int Id { get; set; }

    [StringLength(45)]
    public string Name { get; set; } = null!;

    public Label DescriptionLabel { get; set; } = null!;

    public int DescriptionLabelId { get; set; }

    public ICollection<Quote> Quotes { get; } = new List<Quote>();
}

When we get a GET request we use the following trivial model:

public class Author
{
    public Author() {}

    public Author(Core.Entities.Author model)
    {
        Id = model.Id;
        Name = model.Name;
        DescriptionLabel = new Label(model.DescriptionLabel);
    }

    public int Id { get; set; }

    public string Name { get; set; } = null!;

    public Label DescriptionLabel { get; set; } = null!;
}

Important here is that the DescriptionLabel can not be null. But if I want to process a POST or PUT request, I will want to be able to allow that the DescriptionLabel is null. So my question is, should I just use the GET model and make the label there nullable or do I have to create a new model just for the label to be nullable there?

what are some standards for small differences in the models for Getting and Posting data to a web api?

Answer 1

Short example on separate input output classes inside controller. Key to note also is that each controller class have only one method. This is to keep it more clean. I find this approach simple and easy to read.

[ApiController]
[Route("[controller]")]
[AllowAnonymous]
public class SignIn : ControllerBase
{
    [HttpPost]
    public Output Post(Input input)
    {
        var user = Users.ValidateLoginCredentials(input.Email, input.Password);
        if (user != null)
        {
            return new Output
            {
                FirstName = user.FirstName,
                LastName = user.LastName,
                JWT = GenerateJWT(user)
            };
        }
        return null;
    }

    public class Input
    {
        public string Email { get; set; }
        public string Password { get; set; }
    }

    public class Output
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string JWT { get; set; }
    }
}