How to use inheritance in controller action request?

What is the easiest way to use inheritance in action using ASP.NET CORE MVC?

For example, I have 3 classes:

public class Common { public string CommonField { get; set; } } public class A : Common { public string FieldA { get; set; } } public class B : Common { public string FieldB { get; set; } } 

I have controller action

IActionResult Post([FromBody] [ModelBinder(BinderType = typeof(MyCustomeBinder))] Common field) { //process field here } 

what is the best way to replace field initialization(based on some query parameter (for example, type=a)) in action before binding? I still need all properties to be filled from body.

I already have something like:

public class MyCustomBinder : IModelBinder { public Task BindModelAsync(ModelBindingContext bindingContext) { switch (bindingContext.HttpContext.Request.Headers["type"]) { case "a": bindingContext.Result = ModelBindingResult.Success(new A()); break; case "b": bindingContext.Result = ModelBindingResult.Success(new B()); break; default: } return TaskCache.CompletedTask; } } 

It's correct object coming to action, but all fields are empty.