How to return customized JSON response for an error in graphene / django-graphene? - graphene-python

Question

I want to add status field to error response, so instead of this:
{
"errors": [
{
"message": "Authentication credentials were not provided",
"locations": [
{
"line": 2,
"column": 3
}
]
}
],
"data": {
"viewer": null
}
}
It should be like this:
{
"errors": [
{
"status": 401, # or 400 or 403 or whatever error status suits
"message": "Authentication credentials were not provided",
"locations": [
{
"line": 2,
"column": 3
}
]
}
],
"data": {
"viewer": null
}
}
I found out that I only can change message by raising Exception inside resolver: raise Error('custom error message'), but how to add field?
Code example:
class Query(UsersQuery, graphene.ObjectType):
me = graphene.Field(SelfUserNode)
def resolve_me(self, info: ResolveInfo):
user = info.context.user
if not user.is_authenticated:
# but status attr doesn't exist...
raise GraphQLError('Authentication credentials were not provided', status=401)
return user

Answer 1

Update the default GraphQLView with the following:
from graphene_django.views import GraphQLView as BaseGraphQLView
class GraphQLView(BaseGraphQLView):
#staticmethod
def format_error(error):
formatted_error = super(GraphQLView, GraphQLView).format_error(error)
try:
formatted_error['context'] = error.original_error.context
except AttributeError:
pass
return formatted_error
urlpatterns = [
path('api', GraphQLView.as_view()),
]
This will look for the context attribute in any exceptions raised. If it exists, it'll populate the error with this data.
Now you can create exceptions for different use cases that populate the context attribute. In this case you want to add the status code to errors, here's an example of how you'd do that:
class APIException(Exception):
def __init__(self, message, status=None):
self.context = {}
if status:
self.context['status'] = status
super().__init__(message)
You'd use it like this:
raise APIException('Something went wrong', status=400)

Answer 2

I didn't found a way to solve your problem int the way that you propose, otherwise i extend the LoginRequiredMixin class like this:
class LoginRequiredMixin:
def dispatch(self, info, *args, **kwargs):
if not info.user.is_authenticated:
e = HttpError(HttpResponse(status=401, content_type='application/json'), 'Please log in first')
response = e.response
response.content = self.json_encode(info, [{'errors': [self.format_error(e)]}])
return response
return super().dispatch(info, *args, **kwargs)
class PrivateGraphQLView(LoginRequiredMixin, GraphQLView):
schema=schema
and in your url:
from django.views.decorators.csrf import csrf_exempt
from educor.schema import PrivateGraphQLView
url(r'^graphql', csrf_exempt(PrivateGraphQLView.as_view(batch=True)))
you can't see the status with the graphiql but in your client you can get it in the headers or you could modify this line to add in the response response.content = self.json_encode(info, [{'errors': [self.format_error(e)]}])
. Hope it helps anyway i'll leave you another possible solution https://github.com/graphql-python/graphene-django/issues/252