Add batching params (#260)

Add parameters to toggle batching on or off. This can be configured at 2 levels:
- we can configure all the fields of a type at once via SQLAlchemyObjectType.meta.batching
- or we can specify it for a specific field via ORMfield.batching. This trumps SQLAlchemyObjectType.meta.batching.

graphene_sqlalchemy/converter.py

@@ -3,21 +3,28 @@
 from singledispatch import singledispatch
 from sqlalchemy import types
 from sqlalchemy.dialects import postgresql
-from sqlalchemy.orm import interfaces
+from sqlalchemy.orm import interfaces, strategies
 
 from graphene import (ID, Boolean, Dynamic, Enum, Field, Float, Int, List,
                       String)
 from graphene.types.json import JSONString
 
+from .batching import get_batch_resolver
 from .enums import enum_for_sa_enum
+from .fields import (BatchSQLAlchemyConnectionField,
+                     default_connection_field_factory)
 from .registry import get_global_registry
+from .resolvers import get_attr_resolver, get_custom_resolver
 
 try:
     from sqlalchemy_utils import ChoiceType, JSONType, ScalarListType, TSVectorType
 except ImportError:
     ChoiceType = JSONType = ScalarListType = TSVectorType = object
 
 
+is_selectin_available = getattr(strategies, 'SelectInLoader', None)
+
+
 def get_column_doc(column):
     return getattr(column, "doc", None)
 
@@ -26,33 +33,82 @@ def is_column_nullable(column):
     return bool(getattr(column, "nullable", True))
 
 
-def convert_sqlalchemy_relationship(relationship_prop, registry, connection_field_factory, resolver, **field_kwargs):
-    direction = relationship_prop.direction
-    model = relationship_prop.mapper.entity
-
+def convert_sqlalchemy_relationship(relationship_prop, obj_type, connection_field_factory, batching,
+                                    orm_field_name, **field_kwargs):
+    """
+    :param sqlalchemy.RelationshipProperty relationship_prop:
+    :param SQLAlchemyObjectType obj_type:
+    :param function|None connection_field_factory:
+    :param bool batching:
+    :param str orm_field_name:
+    :param dict field_kwargs:
+    :rtype: Dynamic
+    """
     def dynamic_type():
-        _type = registry.get_type_for_model(model)
+        """:rtype: Field|None"""
+        direction = relationship_prop.direction
+        child_type = obj_type._meta.registry.get_type_for_model(relationship_prop.mapper.entity)
+        batching_ = batching if is_selectin_available else False
 
-        if not _type:
+        if not child_type:
             return None
+
         if direction == interfaces.MANYTOONE or not relationship_prop.uselist:
-            return Field(
-                _type,
-                resolver=resolver,
-                **field_kwargs
-            )
-        elif direction in (interfaces.ONETOMANY, interfaces.MANYTOMANY):
-            if _type.connection:
-                # TODO Add a way to override connection_field_factory
-                return connection_field_factory(relationship_prop, registry, **field_kwargs)
-            return Field(
-                List(_type),
-                **field_kwargs
-            )
+            return _convert_o2o_or_m2o_relationship(relationship_prop, obj_type, batching_, orm_field_name,
+                                                    **field_kwargs)
+
+        if direction in (interfaces.ONETOMANY, interfaces.MANYTOMANY):
+            return _convert_o2m_or_m2m_relationship(relationship_prop, obj_type, batching_,
+                                                    connection_field_factory, **field_kwargs)
 
     return Dynamic(dynamic_type)
 
 
+def _convert_o2o_or_m2o_relationship(relationship_prop, obj_type, batching, orm_field_name, **field_kwargs):
+    """
+    Convert one-to-one or many-to-one relationshsip. Return an object field.
+
+    :param sqlalchemy.RelationshipProperty relationship_prop:
+    :param SQLAlchemyObjectType obj_type:
+    :param bool batching:
+    :param str orm_field_name:
+    :param dict field_kwargs:
+    :rtype: Field
+    """
+    child_type = obj_type._meta.registry.get_type_for_model(relationship_prop.mapper.entity)
+
+    resolver = get_custom_resolver(obj_type, orm_field_name)
+    if resolver is None:
+        resolver = get_batch_resolver(relationship_prop) if batching else \
+            get_attr_resolver(obj_type, relationship_prop.key)
+
+    return Field(child_type, resolver=resolver, **field_kwargs)
+
+
+def _convert_o2m_or_m2m_relationship(relationship_prop, obj_type, batching, connection_field_factory, **field_kwargs):
+    """
+    Convert one-to-many or many-to-many relationshsip. Return a list field or a connection field.
+
+    :param sqlalchemy.RelationshipProperty relationship_prop:
+    :param SQLAlchemyObjectType obj_type:
+    :param bool batching:
+    :param function|None connection_field_factory:
+    :param dict field_kwargs:
+    :rtype: Field
+    """
+    child_type = obj_type._meta.registry.get_type_for_model(relationship_prop.mapper.entity)
+
+    if not child_type._meta.connection:
+        return Field(List(child_type), **field_kwargs)
+
+    # TODO Allow override of connection_field_factory and resolver via ORMField
+    if connection_field_factory is None:
+        connection_field_factory = BatchSQLAlchemyConnectionField.from_relationship if batching else \
+            default_connection_field_factory
+
+    return connection_field_factory(relationship_prop, obj_type._meta.registry, **field_kwargs)
+
+
 def convert_sqlalchemy_hybrid_method(hybrid_prop, resolver, **field_kwargs):
     if 'type' not in field_kwargs:
         # TODO The default type should be dependent on the type of the property propety.

graphene_sqlalchemy/resolvers.py

@@ -0,0 +1,26 @@
+from graphene.utils.get_unbound_function import get_unbound_function
+
+
+def get_custom_resolver(obj_type, orm_field_name):
+    """
+    Since `graphene` will call `resolve_<field_name>` on a field only if it
+    does not have a `resolver`, we need to re-implement that logic here so
+    users are able to override the default resolvers that we provide.
+    """
+    resolver = getattr(obj_type, 'resolve_{}'.format(orm_field_name), None)
+    if resolver:
+        return get_unbound_function(resolver)
+
+    return None
+
+
+def get_attr_resolver(obj_type, model_attr):
+    """
+    In order to support field renaming via `ORMField.model_attr`,
+    we need to define resolver functions for each field.
+
+    :param SQLAlchemyObjectType obj_type:
+    :param str model_attr: the name of the SQLAlchemy attribute
+    :rtype: Callable
+    """
+    return lambda root, _info: getattr(root, model_attr, None)

graphene_sqlalchemy/tests/test_batching.py

@@ -6,8 +6,9 @@
 import graphene
 from graphene import relay
 
-from ..fields import BatchSQLAlchemyConnectionField
-from ..types import SQLAlchemyObjectType
+from ..fields import (BatchSQLAlchemyConnectionField,
+                      default_connection_field_factory)
+from ..types import ORMField, SQLAlchemyObjectType
 from .models import Article, HairKind, Pet, Reporter
 from .utils import is_sqlalchemy_version_less_than, to_std_dicts
 
@@ -43,19 +44,19 @@ class ReporterType(SQLAlchemyObjectType):
         class Meta:
             model = Reporter
             interfaces = (relay.Node,)
-            connection_field_factory = BatchSQLAlchemyConnectionField.from_relationship
+            batching = True
 
     class ArticleType(SQLAlchemyObjectType):
         class Meta:
             model = Article
             interfaces = (relay.Node,)
-            connection_field_factory = BatchSQLAlchemyConnectionField.from_relationship
+            batching = True
 
     class PetType(SQLAlchemyObjectType):
         class Meta:
             model = Pet
             interfaces = (relay.Node,)
-            connection_field_factory = BatchSQLAlchemyConnectionField.from_relationship
+            batching = True
 
     class Query(graphene.ObjectType):
         articles = graphene.Field(graphene.List(ArticleType))
@@ -513,3 +514,187 @@ def test_many_to_many(session_factory):
         },
       ],
     }
+
+
+def test_disable_batching_via_ormfield(session_factory):
+    session = session_factory()
+    reporter_1 = Reporter(first_name='Reporter_1')
+    session.add(reporter_1)
+    reporter_2 = Reporter(first_name='Reporter_2')
+    session.add(reporter_2)
+    session.commit()
+    session.close()
+
+    class ReporterType(SQLAlchemyObjectType):
+        class Meta:
+            model = Reporter
+            interfaces = (relay.Node,)
+            batching = True
+
+        favorite_article = ORMField(batching=False)
+        articles = ORMField(batching=False)
+
+    class ArticleType(SQLAlchemyObjectType):
+        class Meta:
+            model = Article
+            interfaces = (relay.Node,)
+
+    class Query(graphene.ObjectType):
+        reporters = graphene.Field(graphene.List(ReporterType))
+
+        def resolve_reporters(self, info):
+            return info.context.get('session').query(Reporter).all()
+
+    schema = graphene.Schema(query=Query)
+
+    # Test one-to-one and many-to-one relationships
+    with mock_sqlalchemy_logging_handler() as sqlalchemy_logging_handler:
+        # Starts new session to fully reset the engine / connection logging level
+        session = session_factory()
+        schema.execute("""
+          query {
+            reporters {
+              favoriteArticle {
+                headline
+              }
+            }
+          }
+        """, context_value={"session": session})
+        messages = sqlalchemy_logging_handler.messages
+
+    select_statements = [message for message in messages if 'SELECT' in message and 'FROM articles' in message]
+    assert len(select_statements) == 2
+
+    # Test one-to-many and many-to-many relationships
+    with mock_sqlalchemy_logging_handler() as sqlalchemy_logging_handler:
+        # Starts new session to fully reset the engine / connection logging level
+        session = session_factory()
+        schema.execute("""
+          query {
+            reporters {
+              articles {
+                edges {
+                  node {
+                    headline
+                  }
+                }
+              }
+            }
+          }
+        """, context_value={"session": session})
+        messages = sqlalchemy_logging_handler.messages
+
+    select_statements = [message for message in messages if 'SELECT' in message and 'FROM articles' in message]
+    assert len(select_statements) == 2
+
+
+def test_connection_factory_field_overrides_batching_is_false(session_factory):
+    session = session_factory()
+    reporter_1 = Reporter(first_name='Reporter_1')
+    session.add(reporter_1)
+    reporter_2 = Reporter(first_name='Reporter_2')
+    session.add(reporter_2)
+    session.commit()
+    session.close()
+
+    class ReporterType(SQLAlchemyObjectType):
+        class Meta:
+            model = Reporter
+            interfaces = (relay.Node,)
+            batching = False
+            connection_field_factory = BatchSQLAlchemyConnectionField.from_relationship
+
+        articles = ORMField(batching=False)
+
+    class ArticleType(SQLAlchemyObjectType):
+        class Meta:
+            model = Article
+            interfaces = (relay.Node,)
+
+    class Query(graphene.ObjectType):
+        reporters = graphene.Field(graphene.List(ReporterType))
+
+        def resolve_reporters(self, info):
+            return info.context.get('session').query(Reporter).all()
+
+    schema = graphene.Schema(query=Query)
+
+    with mock_sqlalchemy_logging_handler() as sqlalchemy_logging_handler:
+        # Starts new session to fully reset the engine / connection logging level
+        session = session_factory()
+        schema.execute("""
+          query {
+            reporters {
+              articles {
+                edges {
+                  node {
+                    headline
+                  }
+                }
+              }
+            }
+          }
+        """, context_value={"session": session})
+        messages = sqlalchemy_logging_handler.messages
+
+    if is_sqlalchemy_version_less_than('1.3'):
+        # The batched SQL statement generated is different in 1.2.x
+        # SQLAlchemy 1.3+ optimizes out a JOIN statement in `selectin`
+        # See https://git.io/JewQu
+        select_statements = [message for message in messages if 'SELECT' in message and 'JOIN articles' in message]
+    else:
+        select_statements = [message for message in messages if 'SELECT' in message and 'FROM articles' in message]
+    assert len(select_statements) == 1
+
+
+def test_connection_factory_field_overrides_batching_is_true(session_factory):
+    session = session_factory()
+    reporter_1 = Reporter(first_name='Reporter_1')
+    session.add(reporter_1)
+    reporter_2 = Reporter(first_name='Reporter_2')
+    session.add(reporter_2)
+    session.commit()
+    session.close()
+
+    class ReporterType(SQLAlchemyObjectType):
+        class Meta:
+            model = Reporter
+            interfaces = (relay.Node,)
+            batching = True
+            connection_field_factory = default_connection_field_factory
+
+        articles = ORMField(batching=True)
+
+    class ArticleType(SQLAlchemyObjectType):
+        class Meta:
+            model = Article
+            interfaces = (relay.Node,)
+
+    class Query(graphene.ObjectType):
+        reporters = graphene.Field(graphene.List(ReporterType))
+
+        def resolve_reporters(self, info):
+            return info.context.get('session').query(Reporter).all()
+
+    schema = graphene.Schema(query=Query)
+
+    with mock_sqlalchemy_logging_handler() as sqlalchemy_logging_handler:
+        # Starts new session to fully reset the engine / connection logging level
+        session = session_factory()
+        schema.execute("""
+          query {
+            reporters {
+              articles {
+                edges {
+                  node {
+                    headline
+                  }
+                }
+              }
+            }
+          }
+        """, context_value={"session": session})
+        messages = sqlalchemy_logging_handler.messages
+
+    select_statements = [message for message in messages if 'SELECT' in message and 'FROM articles' in message]
+    assert len(select_statements) == 2