Send HTTP 204 response with Google Cloud Endpoints - google-app-engine

Question

I'm creating an API using Google Cloud Endpoints where I would like to return a "no content" HTTP 204 response if there's nothing to return. I tried returning null, which throws an error on the development server, and a non-empty result on production with status code 200.
It is possible to send out a true 204 empty response or other types or custom responses?

Answer 1

To return a 204 No Content for a production Python Cloud Endpoints API, you can use VoidMessage.
from google.appengine.ext import endpoints
from protorpc import messages
from protorpc import message_types
from protorpc import remote
class MyMessage(messages.Message):
...
#endpoints.api('someapi', 'v1', 'Description')
class MyApi(remote.Service):
#endpoints.method(MyMessage, message_types.VoidMessage,
...)
def my_method(self, request):
...
return message_types.VoidMessage()
This currently returns a 200 on the development server, thanks for finding this bug!

Answer 2

This probably doesn't help, but the only way I know to manipulate the status code is by raising an exception. There are a default set of exceptions provided which map to 400, 401, 403, 404 and 500. The docs say you can subclass endpoints.ServiceException to generate other status codes, however I haven't been able to get this to work. If you set http_status to anything other than one of those listed above, it always results in a 400.
class TestException(endpoints.ServiceException):
http_status = httplib.NO_CONTENT
I run a test in my handler like this:
raise TestException('The status should be 204')
And I see this output when testing it using the API explorer:
400 Bad Request
- Show headers -
{
"error": {
"errors": [
{
"domain": "global",
"reason": "badRequest",
"message": "The status should be 204"
}
],
"code": 400,
"message": "The status should be 204"
}
}