Asp.Net Core - Model Binding For Generic Model Stopped Working After Upgrade To Core 3.0

Question

I have an Asp.Net Core Web Api project that I just upgraded from 2.2 to 3.0. In my app I have entities were the keys can be either string, guid, int (a lot of Legacy code). In order to manage some of the API requests in a generic way, I've created this view model:

public class EntityRequestViewModel<T>
{
    [Required]
    public T Id;
}

Which I used in different controllers like

[HttpPost]
    [Route("delete")]
    public async Task<IActionResult> Delete([FromBody]EntityRequestViewModel<Guid> deleteEntityRequest)
    {
      //Do something
    }

There are also many view models extending this EntityRequestViewModel. This worked great, but for some reason, after the upgrade, the value is not bound to the Id.

Answer 1

The generic parameter is fine, what you are doing wrong is that this is a public field :

public T Id;

What you really need for model binding to kick in is a property with a public setter:

public T Id { get; set; }