Question

Assuming a ApiController with an action having multiple arguments:

[HttpPost]
public void AddAddress( Person person, Address address, int simple )

Or something like that.
Now I try to send a post request with content type application/json and json like this:

{
  person: {...}, address: {..}, simple: 1
}

just assume it’s valid json 😉

or in a json array like this:
[person, address, simple]

But WebApi won’t recognize this and tell me it can’t find the action, as it doesn’t support multiple parameters in a json request.

I’m doing this from a C# client using HttpClient and we’d like to do post requests using json. I wanted to use the WebApi.Client package, which provides several useful extensions to the HttpClient, but we have a portable library project(which webapi client doesn’t support).

How would I go about supporting this feature?

I tried to use an custom ActionFilter, which never get’s to run as it can’t find the action beforehand. I tried MediaTypeFormatter which doesn’t know the context and the arguments, and also I tried ModelBinder, which also seems only on a per argument basis and doesn’t always get executed.

Thanks!

Answer 1

The built-in parameter binding strategy in ASP.NET Web API with formatters only supports a single complex argument mapped to the request body. In your case, you are trying to map at least two complex arguments. The simplest solution without extending this infrastructure would be to create a new model class containing those arguments as properties

public class AddressModel
{
  public Person Person { get; set; }
  public Address Address { get; set; }
  public int Simple { get; set; }
}

And use that model in your controller action

public void AddAddress( AddressModel model );