Asp.Net Web API 2 model not automatically binding

Question

Simple ApiController method:

public class TestController : ApiController
{
    public void TakeIt(MyObject o){
        Console.Write(o.ToString());
    }
}

Simple data type:

public class MyObject{
    public string V1{ get; set; }
    public string V2{ get; set; }
}

Simple post:

POST http://localhost:11026/api/test/takeit HTTP/1.1
Accept: application/json
Content-Type: application/json
Host: localhost:11026

{"V1":"Something","V2": "Something else"}

For some reason the MyObject o will not automatically bind from the JSON form post body (even with [FromBody] inserted before the parameter on the method.

Am I doing something wrong?

SOLUTION (DUH!)

To debug my incoming requests, I had put this in my global.asax (because I was failing to get the requests to flow through Fiddler) so I could inspect them first

    protected void Application_BeginRequest()
    {
        using (Stream receiveStream = Request.InputStream)
        {
            using (StreamReader readStream = new StreamReader(receiveStream, Encoding.UTF8))
            {
                var content = readStream.ReadToEnd();
                Console.WriteLine(content);
            }
        }
    }

This was stopping anything down the line from reading the posted data. Soon as I removed that, the automatic model binding worked fine.

Mark Wagoner · Accepted Answer · 2017-07-27 12:46:31Z

1

I think you either need to decorate your method with [HttpPost] or rename it to PostTakeIt. Web API defaults to GET I believe.

answered Jul 27, 2017 at 12:46

Mark Wagoner

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Comments

Nkosi · Accepted Answer · 2017-07-27 12:55:47Z

1

Two things

public class TestController : ApiController
{
    [HttpPost]
    public void TakeIt([FromBody]MyObject o){
        Console.Write(o.ToString());
    }
}

Tag the action with HttpPost as is it not actually conforming to convention-based routing, and next tag the parameter with [FromBody] so the model binder know where to look for the model.

Also, given the URI api/test/takeit the assumption here is that the route template is api/{controller}/{action}.

The default template is usually api/{controller}/

// Convention-based routing.
config.Routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{id}",
    defaults: new { id = RouteParameter.Optional }
);

which does not cater for the action name.

You would either have to add another route

// Convention-based routing.    
config.Routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{id}",
    defaults: new { id = RouteParameter.Optional }
);

config.Routes.MapHttpRoute(
    name: "DefaultActionApi",
    routeTemplate: "api/{controller}/{action}/{id}",
    defaults: new { id = RouteParameter.Optional }
);

or use Attribute routing

// Attribute routing.
config.MapHttpAttributeRoutes();

// Convention-based routing.
config.Routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{id}",
    defaults: new { id = RouteParameter.Optional }
);

With updated controller

[RoutePrefix("api/test")]
public class TestController : ApiController
{
    [HttpPost]
    [Route("takeit")] //Matches POST api/test/takeit
    public IHttpActionResult TakeIt([FromBody]MyObject o){
        Console.Write(o.ToString());
        return Ok();
    }
}

edited Jul 27, 2017 at 12:55

answered Jul 27, 2017 at 12:48

Nkosi

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3 Comments

Jimbo Over a year ago

I should have explicitly stated that I changed the API route mapper to "api/{controller}/{action}/{id}". Unfortunately neither adding [FromBody] to the parameter nor [HttpPost] to the method makes any difference to the binding on my controller. I have a feeling its a config setting somewhere that is missing.

Nkosi Over a year ago

@Jimbo I would have to agree. There is not enough info in the OP for use to tell though. provide a minimal reproducible example that can be used to reproduce your problem and help find a solution.

Jimbo Over a year ago

Dammit, knew it was something simple... I have put more info in my OP explaining why this wasnt working. Thanks for your efforts.

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