Queries do not support multiple inheritance

[adamcharnock]

Use Case: splitting out query definition logic into smaller and more manageable files (e.g. in Django app directories)

Something like this will not currently work:

schema = graphene.Schema(name='Swiftwind Schema')


class Query1(ObjectType):
    all_accounts = relay.ConnectionField(accounts_nodes.Account)
    account = relay.NodeField(accounts_nodes.Account)


class Query2(ObjectType):
    all_transactions = relay.ConnectionField(accounts_nodes.Transaction)
    transaction = relay.NodeField(accounts_nodes.Transaction)


class Query3(ObjectType):
    all_users = relay.ConnectionField(accounts_nodes.User)
    resolve_all_users = ConnectionResolver(accounts_nodes.User)


class Query(Query1, Query2, Query3):
    pass


schema.query = Query

It dies with the following error:

  File "/Users/adam/Envs/swiftwind/src/graphql-core/graphql/core/type/schema.py", line 30, in __init__
    assert isinstance(query, GraphQLObjectType), 'Schema query must be Object Type but got: {}.'.format(query)

I have also tried:

schema = graphene.Schema(name='Swiftwind Schema')


class Query1(object):
    all_accounts = relay.ConnectionField(accounts_nodes.Account)
    account = relay.NodeField(accounts_nodes.Account)


class Query2(object):
    all_transactions = relay.ConnectionField(accounts_nodes.Transaction)
    transaction = relay.NodeField(accounts_nodes.Transaction)


class Query3(object):
    all_users = relay.ConnectionField(accounts_nodes.User)
    resolve_all_users = ConnectionResolver(accounts_nodes.User)


class Query(Query1, Query2, Query3, ObjectType):
    pass


schema.query = Query

Which dies with the error:

  File "/Users/adam/Envs/swiftwind/src/graphql-core/graphql/core/type/definition.py", line 211, in define_field_map
    ).format(type)
AssertionError: Query fields must be a mapping (dict / OrderedDict) with field names as keys or a function which returns such a mapping.

Presumably because the fields never get initialised?

Anyway, if this is possible I'd love to know how.

[syrusakbary]

The main reason is:

• In the first example, the Query object, as inherits more than one ObjectType is automatically mapped to a Union type. Some how graphql doesn't allow union types for the root query object.
• In the second example, the objects are not inheriting for ObjectType, so when Query inherit those objects is not copying their fields.

However I certainly believe we should be able to do this in a good way.
I'm thinking about create the concept of abstract ObjectTypes so you can extend from them without converting in a UnionType.
Something like:

class Query1(ObjectType):
    class Meta:
        abstract = True
    all_accounts = relay.ConnectionField(accounts_nodes.Account)
    account = relay.NodeField(accounts_nodes.Account)


class Query2(ObjectType):
    class Meta:
        abstract = True
    all_transactions = relay.ConnectionField(accounts_nodes.Transaction)
    transaction = relay.NodeField(accounts_nodes.Transaction)


class Query3(ObjectType):
    class Meta:
        abstract = True
    all_users = relay.ConnectionField(accounts_nodes.User)
    resolve_all_users = ConnectionResolver(accounts_nodes.User)


class Query(Query1, Query2, Query3):
    pass

Thoughts?

[adamcharnock]

I think that looks like a good solution. It like that it has some parity with Django's models. Ideally we wouldn't have to specify that a Query is abstract and things would just work, but given that this is not possible I think this is a good solution. 👍

[ustun]

This is an interesting topic. Should each django app have its own schema? Then, how do we prevent name collisions? Should we be prefixing the resources then or should each app be serving its own graphql schema at a different URL?

Some of these are subjective, but it would be better if we could give some recommended best practices to the community there.

[jcouser]

Hi,

I'm attempting to create this level of abstraction as well. I'm using graphql-sqlalchemy and when I do something like:

class UserGroupMember(SQLAlchemyObjectType):
    class Meta:
        abstract = True
        model = UserGroupMemberModel
        interfaces = (CustomNode, )

I'm getting the following error:

TypeError: Invalid attributes: abstract