WebApi Put "The parameters dictionary contains a null entry for parameter..." - asp.net-mvc-4

Question

public class ContactsController : ApiController
{
private static readonly List<Contact> _contacts = new List<Contact>();
public Contact PutContacts(int id, Contact contact)
{
if (_contacts.Any(c => c.Id == contact.Id) == false)
{
throw new HttpResponseException(HttpStatusCode.NotFound);
}
contact.LastModified = DateTime.Now;
return contact;
}
}
http put header:
PUT /api/contacts/3 HTTP/1.1
User-Agent: Fiddler
Content-Type: application/json
Host: localhost:8080
body:
{"Id":3,"Name":"mmm","Phone":"000 000 0000","Email":"mmm#gmail.com","LastModified":"2012-03-08T23:42:13.8681395+08:00"}
response:
HTTP/1.1 400 Bad Request
"The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'SelfHost.Contact PutContacts(Int32, SelfHost.Contact)' in 'SelfHost.ContactsController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter."
Why? thanks.
PS:
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);

Answer 1

I am having this same issue. The query parameter, "id" is null and the object "contact" is filled in. I think this is a model binding issue. If you put a break point in the controller, look at this expression:
this.ControllerContext.RouteData.Values["id"]
You will see that the value is there in the route data; its just not getting set on the model. I have an ActionFilter and if I put a break point in there as well, I see that the actionContext's ActionArgument has a key for it, but a null value.
Im still researching...

Answer 2

I am unable to reproduce the issue you are describing.
Model:
public class Contact
{
public int Id { get; set; }
public string Name { get; set; }
public string Phone { get; set; }
public string Email { get; set; }
public DateTime LastModified { get; set; }
}
Controller:
public class ContactsController : ApiController
{
public Contact Put(int id, Contact contact)
{
return contact;
}
}
Client:
class Program
{
static void Main()
{
using (var client = new WebClient())
{
client.Headers[HttpRequestHeader.ContentType] = "application/json";
var data = Encoding.UTF8.GetBytes(#"{""Id"":3,""Name"":""mmm"",""Phone"":""000 000 0000"",""Email"":""mmm#gmail.com"",""LastModified"":""2012-03-08T23:42:13.8681395+08:00""}");
var result = client.UploadData("http://localhost:1405/api/contacts/4", "PUT", data);
Console.WriteLine(Encoding.UTF8.GetString(result));
}
}
}
When I run the client, the following request is being sent:
PUT /api/contacts/4 HTTP/1.1
Content-Type: application/json
Host: localhost:1405
Content-Length: 119
Expect: 100-continue
Connection: Keep-Alive
{"Id":3,"Name":"mmm","Phone":"000 000 0000","Email":"mmm#gmail.com","LastModified":"2012-03-08T23:42:13.8681395+08:00"}
and I get the correct result from the server. So I guess that the request you are showing is not the actual request that's being sent to the server.

Answer 3

craigtadlock, thanks for your help and sending the bug over to Microsoft. I was having the same problem with PUTs. None of them worked. As a workaround, I hacked POST to handle PUT. If the object I'm posting to the server already has it's ID, the POST code treats it as a PUT with that ID. Pseudo code is:
public HttpResponseMessage<MyClass> PostMyClass(MyClass myObject)
{
if( myObject.ID != 0 ){
//do PUT code
}else{
//do POST code
}
}