Exception traceback disappears when running middleware

[Felipe Lacerda]

Here's a small example that illustrates the issue:

import logging

import graphene

logging.basicConfig()


class Query(graphene.ObjectType):
    hello = graphene.String()

    def resolve_hello(self, info):
        raise Exception('error')
        return 'Hello'


schema = graphene.Schema(query=Query)


def middleware(next, root, info, **kwargs):
    return next(root, info, **kwargs)

If we execute a query without any middleware, we get the traceback:

In [3]: schema.execute('{ hello }')
ERROR:graphql.execution.executor:An error occurred while resolving field Query.hello
Traceback (most recent call last):
  File "/home/felipe/.local/share/virtualenvs/graphene-hello-viSdSxbU/local/lib/python2.7/site-packages/graphql/execution/executor.py", line 447, in resolve_or_error
    return executor.execute(resolve_fn, source, info, **args)
  File "/home/felipe/.local/share/virtualenvs/graphene-hello-viSdSxbU/local/lib/python2.7/site-packages/graphql/execution/executors/sync.py", line 16, in execute
    return fn(*args, **kwargs)
  File "<ipython-input-1-89a125ef67fc>", line 12, in resolve_hello
    raise Exception('error')
Exception: error
ERROR:graphql.execution.utils:Traceback (most recent call last):
  File "/home/felipe/.local/share/virtualenvs/graphene-hello-viSdSxbU/local/lib/python2.7/site-packages/graphql/execution/executor.py", line 447, in resolve_or_error
    return executor.execute(resolve_fn, source, info, **args)
  File "/home/felipe/.local/share/virtualenvs/graphene-hello-viSdSxbU/local/lib/python2.7/site-packages/graphql/execution/executors/sync.py", line 16, in execute
    return fn(*args, **kwargs)
  File "<ipython-input-1-89a125ef67fc>", line 12, in resolve_hello
    raise Exception('error')
GraphQLLocatedError: error

But if we run it with the middleware, we get very little information:

In [4]: schema.execute('{ hello }', middleware=[middleware])
ERROR:graphql.execution.utils:GraphQLLocatedError: error

While investigating the issue, it looks like the point the traceback gets lost is around https://github.com/graphql-python/graphql-core/blob/master/graphql/execution/executor.py#L529. The promise gets rejected because of the exception, and then the is_reject handler returns another promise that gets immediately rejected. This new error has no traceback, so it doesn't get logged when it's caught inside complete_value_catching_error.

[Manu Ebert]

Is there a good workaround for this until this is fixed in graphql-core?

[Jessamyn Hodge]

@maebert this could be tidied up, but I'm using this middleware which seems to work well. (obv switch out so it raises what is useful to you, I send things to sentry.io so they weren't relevant to include but you get the idea)

from api.utils.logging import get_logger


class LoggingMiddleware(object):
    @staticmethod
    def resolve(next, root, info, **args):
        logger = get_logger('ctx_logging')
        try:
            return next(root, info, **args)
        except Exception as e:
            logger.error(e)
            logger.warn(args)
            logger.debug(
                "{parent_type}.{field_name}".format(
                    parent_type=root._meta.name
                    if root and hasattr(root, "_meta")
                    else "",
                    field_name=info.field_name,
                )
            )
            raise

[Lucas Simon Rodrigues Magalhaes]

This traceback it's just print on console? Because the tests ran ok.

from graphql import GraphQLError

from .auth import get_authorization_header, decode_token


class AuthorizationMiddleware(object):
    def resolve(self, next, root, info, **args):
        try:
            token = get_authorization_header(info.context.META)
            decode_token(token)
        except GraphQLError as e:
            raise e

        # TODO: get the user in payload
        return next(root, info, **args)

class AllTestCase(GraphQLTestCase, GenerateToken):
    def make_request(self, headers=None):
        token = self.make_jwt().decode('utf-8')
        if headers is None:
            headers = {'Authorization': f'Bearer {token}'}

        response = self._client.post(
            self.GRAPHQL_URL, json.dumps({"query": self.QUERY}), content_type="application/json",
            headers=headers
        )
          return response

    def test_should_returns_error_response_without_headers(self):
        headers = {}
        response = self.make_request(headers)

        content = json.loads(response.content)
        self.assertTrue(content['data']['all'] is None)
        self.assertResponseHasErrors(response)

$ python manage.py test -k
Using existing test database for alias 'default'...
System check identified no issues (0 silenced).
...An error occurred while resolving field Query.all
Traceback (most recent call last):
  File "/Users/lucas/.virtualenvs/invoice/lib/python3.7/site-packages/graphql/execution/executor.py", line 450, in resolve_or_error
    return executor.execute(resolve_fn, source, info, **args)
  File "/Users/lucas/.virtualenvs/invoice/lib/python3.7/site-packages/graphql/execution/executors/sync.py", line 16, in execute
    return fn(*args, **kwargs)
  File "/Users/lucas/dev/projects/invoice-service/utils/middleware.py", line 10, in resolve
    token = get_authorization_header(info.context.META)
  File "/Users/lucas/dev/projects/invoice-service/utils/auth.py", line 14, in get_authorization_header
    raise GraphQLError(Messages.AUTH_NOT_FOUND_AUTHORIZATION.value)
graphql.error.base.GraphQLError: Not found Authorization.
Traceback (most recent call last):
  File "/Users/lucas/.virtualenvs/invoice/lib/python3.7/site-packages/graphql/execution/executor.py", line 450, in resolve_or_error
    return executor.execute(resolve_fn, source, info, **args)
  File "/Users/lucas/.virtualenvs/invoice/lib/python3.7/site-packages/graphql/execution/executors/sync.py", line 16, in execute
    return fn(*args, **kwargs)
  File "/Users/lucas/dev/projects/invoice-service/utils/middleware.py", line 10, in resolve
    token = get_authorization_header(info.context.META)
  File "/Users/lucas/dev/projects/invoice-service/utils/auth.py", line 14, in get_authorization_header
    raise GraphQLError(Messages.AUTH_NOT_FOUND_AUTHORIZATION.value)
graphql.error.located_error.GraphQLLocatedError: Not found Authorization.

.........................................