Returning http status code from Web Api controller
You can also do the following if you want to preserve the action signature as returning User:
public User GetUser(int userId, DateTime lastModifiedAtClient)
If you want to return something other than 200
then you throw an HttpResponseException
in your action and pass in the HttpResponseMessage
you want to send to the client.
I did not know the answer so asked the ASP.NET team here.
So the trick is to change the signature to HttpResponseMessage
and use Request.CreateResponse
.
[ResponseType(typeof(User))]
public HttpResponseMessage GetUser(HttpRequestMessage request, int userId, DateTime lastModifiedAtClient)
{
var user = new DataEntities().Users.First(p => p.Id == userId);
if (user.LastModified <= lastModifiedAtClient)
{
return new HttpResponseMessage(HttpStatusCode.NotModified);
}
return request.CreateResponse(HttpStatusCode.OK, user);
}
Change the GetXxx API method to return HttpResponseMessage and then return a typed version for the full response and the untyped version for the NotModified response.
public HttpResponseMessage GetComputingDevice(string id)
{
ComputingDevice computingDevice =
_db.Devices.OfType<ComputingDevice>()
.SingleOrDefault(c => c.AssetId == id);
if (computingDevice == null)
{
return this.Request.CreateResponse(HttpStatusCode.NotFound);
}
if (this.Request.ClientHasStaleData(computingDevice.ModifiedDate))
{
return this.Request.CreateResponse<ComputingDevice>(
HttpStatusCode.OK, computingDevice);
}
else
{
return this.Request.CreateResponse(HttpStatusCode.NotModified);
}
}
*The ClientHasStale data is my extension for checking ETag and IfModifiedSince headers.
The MVC framework should still serialize and return your object.
NOTE
I think the generic version is being removed in some future version of the Web API.
In MVC 5, things got easier:
return new StatusCodeResult(HttpStatusCode.NotModified, this);