Native SQLAlchemy integration/bindings

[mekarpeles]

See #51, similarly GraphQL-python-archive/graphql-epoxy#5

[mekarpeles]

I'm working on something with no security implications (all data is public), so s a make-shift solution (don't use in production), I'm registering (pseudo code) all models using the following approach crufty:

import Base # = some declarative_base(cls=mixin), see [1]
import graphene
class Query(graphene.ObjectType): pass
for k, v in Base._decl_class_registry.items():
    setattr(Query, k.lower(), v)
    setattr(Query, 'resolve_%s' % k, lambda self, args, info: v.get(args.get('id')).dict()) #dict() coming from [1]

[1] see https://github.com/thegroovebox/api.groovebox.org/blob/master/groovebox/api/core.py#L33

Note: _decl_class_registry has some non-models registered with it (e.g. _sa_module_registry), so additional error handling / logic is required.

[syrusakbary]

@jfeinstein10 already did an amazing work trying to integrate sqlalchemy into graphene.

I'm going to fork its sqlalchemy graphene branch and preserve his work updated with the recent changes of graphene.

[syrusakbary]

Work in progress pull request: #87

[gwind]

@jfeinstein10 I saw this code :

class SQLAlchemyNode(BaseNode, SQLAlchemyInterface):
    id = GlobalIDField()

    @classmethod
    def get_node(cls, id, info=None):
        try:
            instance = cls._meta.model.filter(id=id).one()
            return cls(instance)
        except cls._meta.model.DoesNotExist:
            return None

In the cls._meta.model.filter(id=id).one() , I'm concern:

1. use a django like model query , not original sqlalchemy orm usage.
2. use id as id. Relay ID is a string, model id maybe integer always.

@syrusakbary I'm working on sqlalchemy backend, any progress would be interested.

[syrusakbary]

@gwind some code ported by @jfeinstein10 was not updated to reflect the SQLAlchemy nature, as you exposed.

However is actually fixed by some commits I did recently: https://github.com/graphql-python/graphene/blob/sqlalchemy/graphene/contrib/sqlalchemy/types.py#L122

1. The Relay ID field have to be a String, by spec. The field id in the SQLAlchemy model is mapped to an integer, but this query .filter(id='1') works also well in this cases.

Feel free to fork this work and do any improvements!

[gwind]

@syrusakbary may be a raise NotImplementedError() would be a good choice.

I have a local sqlachemy binding, but it is very basic, and i am not familiar with graphql - relay.
Thanks,

[gwind]

@syrusakbary I've saw that graphene.relay.NodeField in root query would convert original id (int or string) to a uniq ID ( type + id => base64) .

So my concern about instance = cls._meta.model.filter(id=id).one() was wrong: id is the object id in table exactly now.

I've another question: the graphene convert all id to type + id => base64 string, but how to get object by id nicely?

example:

class RootQuery(graphene.ObjectType):
    group = graphene.Field(Group, id=graphene.String().NonNull)

    def resolve_group(self, args, info):
        print("args.get('id') = ", args.get('id'))

this query is ok:

query MyQuery {
  node (id: "R3JvdXA6NA==") {
    id
    ... on Group {
      name
      description
    }
  }
}

but query one object is failed:

query MyQuery {
    group(id:"R3JvdXA6NA==") {
      id
      name
    }
}

In graphene/relay/types , there is a to_global_id() , but no a reverse method such like from_global_id() :

class Node(six.with_metaclass(NodeMeta, Interface)):
    '''An object with an ID'''
    id = GlobalIDField()

    class Meta:
        abstract = True

    def to_global_id(self):
        type_name = self._meta.type_name
        return to_global_id(type_name, self.id)

    connection_type = Connection
    edge_type = Edge

    @classmethod
    def get_connection_type(cls):
        return cls.connection_type

    @classmethod
    def get_edge_type(cls):
        return cls.edge_type

graphql_relay/node/node.py have a from_global_id() indeed

def from_global_id(global_id):
    '''
    Takes the "global ID" created by toGlobalID, and retuns the type name and ID
    used to create it.
    '''
    unbased_global_id = unbase64(global_id)
    _type, _id = unbased_global_id.split(':', 1)
    return ResolvedGlobalId(_type, _id)

Is there a nice method to handle this ?

[syrusakbary]

Graphene is using from_global_id from graphql_relay right now.

However you can customize the id_fetcher function in NodeField (https://github.com/graphql-python/graphene/blob/master/graphene/relay/fields.py#L68)

[gwind]

I see, thanks 😄

[syrusakbary]

SQLAlchemy support is now merged into master, closing the issue 😎