Allow creation of custom connections. Fixes #65.

Previously, it was not possible to create custom connections without
monkey patching graphene.relay.connection. Custom connections are
useful when all connections need a total count for paging, for example.

We change the SQLAlchemyObjectType.__init_subclass_with_meta method
so that when the connection argument is a class, it is used to create
the new connection type.

A test case has been added to check usage of custom connections. The
`conftest.py` was added to allow pytest using database related fixtures
in other places than `test_query.py`.

Author: geertjanvdk

graphene_sqlalchemy/tests/conftest.py

@@ -0,0 +1,40 @@
+import pytest
+from sqlalchemy import create_engine
+from sqlalchemy.orm import scoped_session, sessionmaker
+
+from .models import Article, Base, Editor, Reporter
+from ..registry import reset_global_registry
+
+db = create_engine('sqlite:///test_sqlalchemy.sqlite3')
+
+
+@pytest.yield_fixture(scope='function')
+def session():
+    reset_global_registry()
+    connection = db.engine.connect()
+    transaction = connection.begin()
+    Base.metadata.create_all(connection)
+
+    # options = dict(bind=connection, binds={})
+    session_factory = sessionmaker(bind=connection)
+    session = scoped_session(session_factory)
+
+    yield session
+
+    # Finalize test here
+    transaction.rollback()
+    connection.close()
+    session.remove()
+
+@pytest.yield_fixture(scope='function')
+def setup_fixtures(session):
+    reporter = Reporter(first_name='ABA', last_name='X')
+    session.add(reporter)
+    reporter2 = Reporter(first_name='ABO', last_name='Y')
+    session.add(reporter2)
+    article = Article(headline='Hi!')
+    article.reporter = reporter
+    session.add(article)
+    editor = Editor(name="John")
+    session.add(editor)
+    session.commit()

graphene_sqlalchemy/tests/test_query.py

@@ -1,54 +1,12 @@
-import pytest
-from sqlalchemy import create_engine
-from sqlalchemy.orm import scoped_session, sessionmaker
-
 import graphene
 from graphene.relay import Node
 
-from ..registry import reset_global_registry
+from .models import Article, Editor, Reporter
 from ..fields import SQLAlchemyConnectionField
 from ..types import SQLAlchemyObjectType
-from .models import Article, Base, Editor, Pet, Reporter
-
-db = create_engine('sqlite:///test_sqlalchemy.sqlite3')
-
-
-@pytest.yield_fixture(scope='function')
-def session():
-    reset_global_registry()
-    connection = db.engine.connect()
-    transaction = connection.begin()
-    Base.metadata.create_all(connection)
-
-    # options = dict(bind=connection, binds={})
-    session_factory = sessionmaker(bind=connection)
-    session = scoped_session(session_factory)
-
-    yield session
-
-    # Finalize test here
-    transaction.rollback()
-    connection.close()
-    session.remove()
 
 
-def setup_fixtures(session):
-    pet = Pet(name='Lassie', pet_kind='dog')
-    session.add(pet)
-    reporter = Reporter(first_name='ABA', last_name='X')
-    session.add(reporter)
-    reporter2 = Reporter(first_name='ABO', last_name='Y')
-    session.add(reporter2)
-    article = Article(headline='Hi!')
-    article.reporter = reporter
-    session.add(article)
-    editor = Editor(name="John")
-    session.add(editor)
-    session.commit()
-
-
-def test_should_query_well(session):
-    setup_fixtures(session)
+def test_should_query_well(session, setup_fixtures):
 
     class ReporterType(SQLAlchemyObjectType):
 
@@ -95,42 +53,7 @@ def resolve_reporters(self, *args, **kwargs):
     assert result.data == expected
 
 
-def test_should_query_enums(session):
-    setup_fixtures(session)
-
-    class PetType(SQLAlchemyObjectType):
-
-        class Meta:
-            model = Pet
-
-    class Query(graphene.ObjectType):
-        pet = graphene.Field(PetType)
-
-        def resolve_pet(self, *args, **kwargs):
-            return session.query(Pet).first()
-
-    query = '''
-        query PetQuery {
-          pet {
-            name,
-            petKind
-          }
-        }
-    '''
-    expected = {
-        'pet': {
-            'name': 'Lassie',
-            'petKind': 'dog'
-        }
-    }
-    schema = graphene.Schema(query=Query)
-    result = schema.execute(query)
-    assert not result.errors
-    assert result.data == expected, result.data
-
-
-def test_should_node(session):
-    setup_fixtures(session)
+def test_should_node(session, setup_fixtures):
 
     class ReporterNode(SQLAlchemyObjectType):
 
@@ -229,8 +152,7 @@ def resolve_article(self, *args, **kwargs):
     assert result.data == expected
 
 
-def test_should_custom_identifier(session):
-    setup_fixtures(session)
+def test_should_custom_identifier(session, setup_fixtures):
 
     class EditorNode(SQLAlchemyObjectType):
 
@@ -279,8 +201,7 @@ class Query(graphene.ObjectType):
     assert result.data == expected
 
 
-def test_should_mutate_well(session):
-    setup_fixtures(session)
+def test_should_mutate_well(session, setup_fixtures):
 
     class EditorNode(SQLAlchemyObjectType):
 

graphene_sqlalchemy/tests/test_types.py

@@ -1,10 +1,10 @@
-
-from graphene import Field, Int, Interface, ObjectType
+from graphene import Field, Int, Interface, ObjectType, Connection, Schema
 from graphene.relay import Node, is_node
-import six
+import pytest
 
 from ..registry import Registry
 from ..types import SQLAlchemyObjectType
+from ..fields import SQLAlchemyConnectionField
 from .models import Article, Reporter
 
 registry = Registry()
@@ -72,8 +72,6 @@ def test_node_replacedfield():
 
 
 def test_object_type():
-
-
     class Human(SQLAlchemyObjectType):
         '''Human description'''
 
@@ -90,7 +88,6 @@ class Meta:
     assert is_node(Human)
 
 
-
 # Test Custom SQLAlchemyObjectType Implementation
 class CustomSQLAlchemyObjectType(SQLAlchemyObjectType):
     class Meta:
@@ -116,3 +113,77 @@ def test_custom_objecttype_registered():
         'pets',
         'articles',
         'favorite_article']
+
+
+def test_custom_connection(session, setup_fixtures):
+    exp_counter = 123
+
+    class CustomConnection(Connection):
+        class Meta:
+            abstract = True
+
+        counter = Int()
+
+        @staticmethod
+        def resolve_counter(*args, **kwargs):
+            return exp_counter
+
+    class ArticleType(SQLAlchemyObjectType):
+        class Meta:
+            model = Article
+            connection = CustomConnection
+            interfaces = (Node,)
+            registry = registry
+
+    class Query(ObjectType):
+        articles = SQLAlchemyConnectionField(ArticleType)
+
+    schema = Schema(query=Query)
+    result = schema.execute("query { articles { counter edges { node { headline }}}}",
+                            context_value={'session': session})
+
+    assert not result.errors
+    assert result.data['articles']['counter'] == exp_counter
+    assert result.data['articles']['edges'][0]['node']['headline'] == 'Hi!'
+
+
+def test_automatically_created_connection():
+    expected = "ArticleTypeConnection"
+
+    class ArticleType(SQLAlchemyObjectType):
+        class Meta:
+            model = Article
+            interfaces = (Node,)
+            registry = registry
+
+    assert ArticleType._meta.connection.__name__ == expected
+
+
+def test_passing_connection_instance():
+    expected = "CnxHumanType"
+
+    class HumanType(SQLAlchemyObjectType):
+        class Meta:
+            model = Reporter
+            interfaces = (Node,)
+
+    class ArticleType(SQLAlchemyObjectType):
+        class Meta:
+            model = Article
+            interfaces = (Node,)
+            connection = Connection.create_type(expected, node=HumanType)
+            registry = registry
+
+    assert ArticleType._meta.connection.__name__ == expected
+
+
+def test_passing_incorrect_connection_instance():
+    with pytest.raises(AssertionError) as excinfo:
+        class ArticleType(SQLAlchemyObjectType):
+            class Meta:
+                model = Article
+                interfaces = (Node,)
+                connection = 'spam'
+                registry = registry
+
+    assert "The connection must be a Connection. Received" in str(excinfo.value)

graphene_sqlalchemy/types.py

@@ -1,4 +1,5 @@
 from collections import OrderedDict
+from inspect import isclass
 
 from sqlalchemy.inspection import inspect as sqlalchemyinspect
 from sqlalchemy.ext.hybrid import hybrid_property
@@ -112,20 +113,31 @@ def __init_subclass_with_meta__(cls, model=None, registry=None, skip_registry=Fa
         if use_connection is None and interfaces:
             use_connection = any((issubclass(interface, Node) for interface in interfaces))
 
-        if use_connection and not connection:
-            # We create the connection automatically
-            connection = Connection.create_type('{}Connection'.format(cls.__name__), node=cls)
-
-        if connection is not None:
-            assert issubclass(connection, Connection), (
+        cnx = None
+        if use_connection:
+            if connection and isclass(connection) and issubclass(connection, Connection) and \
+                    not hasattr(connection, '_meta'):
+                # Create connection type automatically using given class
+                cnx = connection.create_type('{}Connection'.format(cls.__name__), node=cls)
+            elif not connection:
+                # Create connection type automatically using graphene.relay.Connection
+                cnx = Connection.create_type('{}Connection'.format(cls.__name__), node=cls)
+            else:
+                cnx = connection
+
+        if cnx is not None:
+            assert isclass(cnx), (
+                "The connection must be a Connection. Received {}"
+            ).format(type(cnx))
+            assert issubclass(cnx, Connection), (
                 "The connection must be a Connection. Received {}"
-            ).format(connection.__name__)
+            ).format(cnx.__name__)
 
         _meta = SQLAlchemyObjectTypeOptions(cls)
         _meta.model = model
         _meta.registry = registry
         _meta.fields = sqla_fields
-        _meta.connection = connection
+        _meta.connection = cnx
         _meta.id = id or 'id'
 
         super(SQLAlchemyObjectType, cls).__init_subclass_with_meta__(_meta=_meta, interfaces=interfaces, **options)