Question about mutation in the documentation

[laurent-brisbois]

Is your feature request related to a problem? Please describe.
No. It is about a clarification that might be helpful about mutations in the documentation.

Describe the solution you'd like
In the documentation, here, in the QuestionMutation class, there is a question attribute. What does that actually mean ? It says that it defines the response and I don't understand this.

In my code I've been able to do this :

My type :

class UserType(DjangoObjectType):

    class Meta:
        model = User
        fields = (
            'id',
            'username',
            'password',
            'email',
            'first_name',
            'last_name',
            'is_active',
            'group_ids',
        )

    full_name = graphene.String()           # Python property
    full_identification = graphene.String() # Python property

My mutation :

class UpdateUser(graphene.Mutation):
    # --------> I could comment these and no problem. Why ? <--------
    # id = graphene.ID()
    # username = graphene.String()
    # email = graphene.String()
    # first_name = graphene.String()
    # last_name = graphene.String()
    # is_active = graphene.Boolean()

    class Arguments:
        id = graphene.ID()
        username = graphene.String()
        email = graphene.String()
        first_name = graphene.String()
        last_name = graphene.String()
        is_active = graphene.Boolean()

    class Meta:
        output = UserType

    @login_required
    def mutate(self, info, **kwargs):
        user = get_object_or_404(User, id=kwargs['id'])
        for attr, value in kwargs.items():
            setattr(user, attr, value)
        user.save()
        return user
        # I'm not returning explicit UserType, is it a problem ?
        # I actually do it with the Meta class. I guess it is the same for this

and it works whereas I didn't specify anything for the response attributes. And I don't even return the same kind of thing.
Can someone explain if I'm doing it wrong ?

[zbyte64]

If you do not define an output type then you must define the return fields on your mutation itself. The example documentation does not define output but opts to return an instance of itself instead. Returning the user model instance works for you because it duck types to UserType.

From the code docs:

output (graphene.ObjectType): Or ``Output`` inner class with attributes on Mutation class.
            Or attributes from Mutation class. Fields which can be returned from this mutation
            field.

[laurent-brisbois]

@zbyte64 Thanks for your answer !
So, I can get rid of the return values in my UserType class since I define the output = UserType which is linked to the User model.
And I can return an instance of the User model while I mentioned output = UserType because these two are bound to each other by model = User

Is that correct ?
Is that a good way to do this ?

[zbyte64]

Generally/Recommended we define the return field at the top level of the class, like user = Field(UserType) instead of using the output meta option. This was we know the exact field name the return value will be, and in the mutate method we return the mutation class with that return value, like cls(user=user) or UpdateUser(user=user).

[laurent-brisbois]

@zbyte64
Okay I see, thanks.
Last thing. You say Generally/Recommended. What does that mean ? That the way I do it isn't exactly the same ? That there are "deep inside differences" ? Or is it for pure conventions and clarity ?

[zbyte64]

I meant it's what I've seen done generally and what I recommend doing for clarity purposes.

[laurent-brisbois]

I see. Thanks for your advices !