I'm creating a new webapi using attribute routing to create a nested route as so:
// PUT: api/Channels/5/Messages
[ResponseType(typeof(void))]
[Route("api/channels/{id}/messages")]
public async Task<IHttpActionResult> PostChannelMessage(int id, Message message)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
if (id != message.ChannelId)
{
return BadRequest();
}
db.Messages.Add(message);
await db.SaveChangesAsync();
return CreatedAtRoute("DefaultApi", new { id = message.Id }, message);
}
I however want to return a route that isn't nested i.e.:
/api/Messages/{id}
which is defined on the messages controller. However The CreatedAtRoute call above is not resolving this route and instead throwing. Have I done something wrong, or does it not support routing to different api controller? n.b. the route I am trying to hit is not an attribute route, just a default one.
The exception is:
Message: "An error has occurred." ExceptionMessage: "UrlHelper.Link must not return null." ExceptionType: "System.InvalidOperationException" StackTrace: " at System.Web.Http.Results.CreatedAtRouteNegotiatedContentResult
1.Execute() at System.Web.Http.Results.CreatedAtRouteNegotiatedContentResult
1.ExecuteAsync(CancellationToken cancellationToken) at System.Web.Http.Controllers.ApiControllerActionInvoker.d__0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter1.GetResult() at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter
1.GetResult() at System.Web.Http.Dispatcher.HttpControllerDispatcher.d__0.MoveNext()"
If it doesn't support this, what is the canonical way to return a 201 and can I do it in a refactor safe way?
Oh dear, this may be a new record for answering my own question.
return CreatedAtRoute("DefaultApi", new { controller = "messages", id = message.Id }, message);
does the trick. i.e. explicitly specifying the controller. I worked this our by seeing that the exception was related to the UrlHelper and reading its docs...