2.0 Bug: Mutations return the field type if output not supplied

[BossGrand]

You can reproduce by creating a simple mutation

import graphene

class TestMutation(grapheneMutation):
    test = graphene.String()

    @classmethod
    def mutate(cls, root, info, **kwargs):
        return TestMutation()

When this mutation is ran the return for test will be

mutation{
    testMutation{
         test
    }
}

"test": "<graphene.types.scalars.String object at 0x108617a20>"

took me a while to figure out what was happening, I'll keep digging see if I can find the root cause. Anyone else running into this issue?

[jlward]

I found this as well.

I was able to "fix" it by making my mutation explicitly set None for each field not being assigned. This fixed a possibly related bug where I was getting errors in the response for custom types and other scalars.

import graphene

class TestMutation(grapheneMutation):
    test = graphene.Int()

    @classmethod
    def mutate(cls, root, info, **kwargs):
        return TestMutation()

mutation{
    testMutation{
         test
    }
}

'errors': [{'message': "int() argument must be a string or a number, not 'Int'"}]

Funny thing is the rest of the response had the correct data (in my case). I think graphene.String accidentally doesn't produce an error because you can call str() on almost anything without it causing an exception.

Hope this helps, and if you would rather I make an independent issue I'd be happy to.

TLDR: Default values are no longer None. So explicitly pass along None for old behavior.

[BossGrand]

Yea thats what I ended up doing to. I have a subclass of mutation that I use on all my mutations so it was relatively painless.

I think that long term this needs to be fixed in the code base

[jlward]

def test():
    class CreateBlank(Mutation):

        class Arguments:
            name = String()

        string = String()
        integer = Int()

        def mutate(self, info, **args):
            return CreateBlank()

    class Query(ObjectType):
        a = String()

    class MyMutation(ObjectType):
        create_blank = CreateBlank.Field()

    schema = Schema(query=Query, mutation=MyMutation)
    result = schema.execute(''' mutation mymutation {
        createBlank(name:"Peter") {
            string
            integer
        }
    }
    ''')
    assert not result.errors
    assert result.data == {
        'createUser': {
            'string': None,
            'integer': None,
        }
    }

I had some trouble figuring out where the problem is happening at. But I was able to create a test that illustrates the issue here. It's not a PR, but since I haven't found where to actually fix it, I'd rather get the test out there. Hopefully it can help someone who actually knows what they are doing fix the problem.

[syrusakbary]

Just fixed this in master. The issue was happening on both ObjectTypes and Mutations (when used as containers)

I also added tests so this issue is not repeated in the future :)