Fixing it up to use the declarative API

graphene/contrib/sqlalchemy/converter.py

@@ -2,16 +2,18 @@ from sqlalchemy import types
 from sqlalchemy.orm import interfaces
 from singledispatch import singledispatch
 
-from graphene.contrib.sqlalchemy.fields import ConnectionOrListField, SQLAlchemyModelField
-from graphene.core.fields import BooleanField, FloatField, IDField, IntField, StringField
+from ...core.types.scalars import Boolean, Float, ID, Int, String
+from .fields import ConnectionOrListField, SQLAlchemyModelField
 
 
 def convert_sqlalchemy_relationship(relationship):
-    model_field = SQLAlchemyModelField(field.table, description=relationship.key)
-    if relationship.direction == interfaces.ONETOMANY:
+    direction = relationship.direction
+    model = relationship.mapper.entity
+    model_field = SQLAlchemyModelField(model, description=relationship.doc)
+    if direction == interfaces.MANYTOONE:
         return model_field
-    elif (relationship.direction == interfaces.MANYTOONE or
-          relationship.direction == interfaces.MANYTOMANY):
+    elif (direction == interfaces.ONETOMANY or
+          direction == interfaces.MANYTOMANY):
         return ConnectionOrListField(model_field)
 
 
@@ -19,43 +21,43 @@ def convert_sqlalchemy_column(column):
     try:
         return convert_sqlalchemy_type(column.type, column)
     except Exception:
-        raise
+        raise Exception(
+            "Don't know how to convert the SQLAlchemy field %s (%s)" % (column, column.__class__))
 
 
 @singledispatch
-def convert_sqlalchemy_type():
-    raise Exception(
-        "Don't know how to convert the SQLAlchemy column %s (%s)" % (column, column.__class__))
+def convert_sqlalchemy_type(type, column):
+    raise Exception()
 
 
 @convert_sqlalchemy_type.register(types.Date)
 @convert_sqlalchemy_type.register(types.DateTime)
 @convert_sqlalchemy_type.register(types.Time)
-@convert_sqlalchemy_type.register(types.Text)
 @convert_sqlalchemy_type.register(types.String)
+@convert_sqlalchemy_type.register(types.Text)
 @convert_sqlalchemy_type.register(types.Unicode)
 @convert_sqlalchemy_type.register(types.UnicodeText)
 @convert_sqlalchemy_type.register(types.Enum)
 def convert_column_to_string(type, column):
-    return StringField(description=column.description)
+    return String(description=column.doc)
 
 
 @convert_sqlalchemy_type.register(types.SmallInteger)
 @convert_sqlalchemy_type.register(types.BigInteger)
 @convert_sqlalchemy_type.register(types.Integer)
-def convert_column_to_int_or_id(column):
+def convert_column_to_int_or_id(type, column):
     if column.primary_key:
-        return IDField(description=column.description)
+        return ID(description=column.doc)
     else:
-        return IntField(description=column.description)
+        return Int(description=column.doc)
 
 
 @convert_sqlalchemy_type.register(types.Boolean)
-def convert_column_to_boolean(column):
-    return BooleanField(description=column.description)
+def convert_column_to_boolean(type, column):
+    return Boolean(description=column.doc)
 
 
 @convert_sqlalchemy_type.register(types.Float)
 @convert_sqlalchemy_type.register(types.Numeric)
-def convert_column_to_float(column):
-    return FloatField(description=column.description)
+def convert_column_to_float(type, column):
+    return Float(description=column.doc)

graphene/contrib/sqlalchemy/fields.py

@@ -1,67 +1,69 @@
-from graphene import relay
-from graphene.contrib.sqlalchemy.utils import get_type_for_model, lazy_map
-from graphene.core.fields import Field, LazyField, ListField
-from graphene.relay.utils import is_node
+from sqlalchemy.orm import Query
+from ...core.exceptions import SkipField
+from ...core.fields import Field
+from ...core.types.base import FieldType
+from ...core.types.definitions import List
+from ...relay import ConnectionField
+from ...relay.utils import is_node
+from ...utils import LazyMap
+
+from .utils import get_type_for_model
 
 
-class SQLAlchemyConnectionField(relay.ConnectionField):
+class SQLAlchemyConnectionField(ConnectionField):
 
     def wrap_resolved(self, value, instance, args, info):
-        schema = info.schema.graphene_schema
-        return lazy_map(value, self.get_object_type(schema))
+        if isinstance(value, Query):
+            return LazyMap(value, self.type)
+        return value
 
 
-class LazyListField(ListField):
+class LazyListField(Field):
 
-    def resolve(self, instance, args, info):
-        schema = info.schema.graphene_schema
-        resolved = super(LazyListField, self).resolve(instance, args, info)
-        return lazy_map(resolved, self.get_object_type(schema))
+    def get_type(self, schema):
+        return List(self.type)
+
+    def resolver(self, instance, args, info):
+        resolved = super(LazyListField, self).resolver(instance, args, info)
+        return LazyMap(resolved, self.type)
 
 
-class ConnectionOrListField(LazyField):
+class ConnectionOrListField(Field):
 
-    def get_field(self, schema):
-        model_field = self.field_type
+    def internal_type(self, schema):
+        model_field = self.type
         field_object_type = model_field.get_object_type(schema)
+        if not field_object_type:
+            raise SkipField()
         if is_node(field_object_type):
-            field = SQLAlchemyConnectionField(model_field)
+            field = SQLAlchemyConnectionField(field_object_type)
         else:
-            field = LazyListField(model_field)
-        field.contribute_to_class(self.object_type, self.name)
-        return field
+            field = LazyListField(field_object_type)
+        field.contribute_to_class(self.object_type, self.attname)
+        return schema.T(field)
 
 
-class SQLAlchemyModelField(Field):
+class SQLAlchemyModelField(FieldType):
 
     def __init__(self, model, *args, **kwargs):
-        super(SQLAlchemyModelField, self).__init__(None, *args, **kwargs)
         self.model = model
-
-    def resolve(self, instance, args, info):
-        resolved = super(SQLAlchemyModelField, self).resolve(instance, args, info)
-        schema = info.schema.graphene_schema
-        _type = self.get_object_type(schema)
-        assert _type, ("Field %s cannot be retrieved as the "
-                       "ObjectType is not registered by the schema" % (
-                           self.attname
-                       ))
-        return _type(resolved)
+        super(SQLAlchemyModelField, self).__init__(*args, **kwargs)
 
     def internal_type(self, schema):
         _type = self.get_object_type(schema)
-        if not _type and self.object_type._meta.only_fields:
+        if not _type and self.parent._meta.only_fields:
             raise Exception(
-                "Model %r is not accessible by the schema. "
+                "Table %r is not accessible by the schema. "
                 "You can either register the type manually "
                 "using @schema.register. "
-                "Or disable the field %s in %s" % (
+                "Or disable the field in %s" % (
                     self.model,
-                    self.attname,
-                    self.object_type
+                    self.parent,
                 )
             )
-        return schema.T(_type) or Field.SKIP
+        if not _type:
+            raise SkipField()
+        return schema.T(_type)
 
     def get_object_type(self, schema):
         return get_type_for_model(schema, self.model)

graphene/contrib/sqlalchemy/options.py

@@ -1,23 +1,23 @@
 import inspect
 
-from sqlalchemy import Table
+from sqlalchemy.ext.declarative.api import DeclarativeMeta
 
-from graphene.core.options import Options
-from graphene.relay.types import Node
-from graphene.relay.utils import is_node
+from ...core.options import Options
+from ...relay.types import Node
+from ...relay.utils import is_node
 
-VALID_ATTRS = ('table', 'only_columns', 'exclude_columns')
+VALID_ATTRS = ('model', 'only_fields', 'exclude_fields')
 
 
 def is_base(cls):
-    from graphene.contrib.SQLAlchemy.types import SQLAlchemyObjectType
+    from graphene.contrib.sqlalchemy.types import SQLAlchemyObjectType
     return SQLAlchemyObjectType in cls.__bases__
 
 
 class SQLAlchemyOptions(Options):
 
     def __init__(self, *args, **kwargs):
-        self.table = None
+        self.model = None
         super(SQLAlchemyOptions, self).__init__(*args, **kwargs)
         self.valid_attrs += VALID_ATTRS
         self.only_fields = None
@@ -30,8 +30,8 @@ class SQLAlchemyOptions(Options):
             self.interfaces.append(Node)
         if not is_node(cls) and not is_base(cls):
             return
-        if not self.table:
+        if not self.model:
             raise Exception(
-                'SQLAlchemy ObjectType %s must have a table in the Meta class attr' % cls)
-        elif not inspect.isclass(self.table) or not issubclass(self.table, Table):
-            raise Exception('Provided table in %s is not a SQLAlchemy table' % cls)
+                'SQLAlchemy ObjectType %s must have a model in the Meta class attr' % cls)
+        elif not inspect.isclass(self.model) or not isinstance(self.model, DeclarativeMeta):
+            raise Exception('Provided model in %s is not a SQLAlchemy model' % cls)

graphene/contrib/sqlalchemy/tests/models.py

@@ -0,0 +1,37 @@
+from __future__ import absolute_import
+
+from sqlalchemy import Table, Column, Integer, String, Date, ForeignKey
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import relationship
+
+
+Base = declarative_base()
+
+association_table = Table('association', Base.metadata,
+    Column('pet_id', Integer, ForeignKey('pets.id')),
+    Column('reporter_id', Integer, ForeignKey('reporters.id')))
+
+
+class Pet(Base):
+    __tablename__ = 'pets'
+    id = Column(Integer(), primary_key=True)
+    name = Column(String(30))
+    reporter_id = Column(Integer(), ForeignKey('reporters.id'))
+
+
+class Reporter(Base):
+    __tablename__ = 'reporters'
+    id = Column(Integer(), primary_key=True)
+    first_name = Column(String(30))
+    last_name = Column(String(30))
+    email = Column(String())
+    pets = relationship('Pet', secondary=association_table, backref='reporters')
+    articles = relationship('Article', backref='reporter')
+
+
+class Article(Base):
+    __tablename__ = 'articles'
+    id = Column(Integer(), primary_key=True)
+    headline = Column(String(100))
+    pub_date = Column(Date())
+    reporter_id = Column(Integer(), ForeignKey('reporters.id'))

graphene/contrib/sqlalchemy/tests/test_converter.py

@@ -0,0 +1,103 @@
+from sqlalchemy import types, Column
+from py.test import raises
+
+import graphene
+from graphene.contrib.sqlalchemy.converter import convert_sqlalchemy_column, convert_sqlalchemy_relationship
+from graphene.contrib.sqlalchemy.fields import ConnectionOrListField, SQLAlchemyModelField
+
+from .models import Article, Reporter, Pet
+
+
+def assert_column_conversion(sqlalchemy_type, graphene_field, **kwargs):
+    column = Column(sqlalchemy_type, doc='Custom Help Text', **kwargs)
+    graphene_type = convert_sqlalchemy_column(column)
+    assert isinstance(graphene_type, graphene_field)
+    field = graphene_type.as_field()
+    assert field.description == 'Custom Help Text'
+    return field
+
+
+def test_should_unknown_sqlalchemy_field_raise_exception():
+    with raises(Exception) as excinfo:
+        convert_sqlalchemy_column(None)
+    assert 'Don\'t know how to convert the SQLAlchemy field' in str(excinfo.value)
+
+
+def test_should_date_convert_string():
+    assert_column_conversion(types.Date(), graphene.String)
+
+
+def test_should_datetime_convert_string():
+    assert_column_conversion(types.DateTime(), graphene.String)
+
+
+def test_should_time_convert_string():
+    assert_column_conversion(types.Time(), graphene.String)
+
+
+def test_should_string_convert_string():
+    assert_column_conversion(types.String(), graphene.String)
+
+
+def test_should_text_convert_string():
+    assert_column_conversion(types.Text(), graphene.String)
+
+
+def test_should_unicode_convert_string():
+    assert_column_conversion(types.Unicode(), graphene.String)
+
+
+def test_should_unicodetext_convert_string():
+    assert_column_conversion(types.UnicodeText(), graphene.String)
+
+
+def test_should_enum_convert_string():
+    assert_column_conversion(types.Enum(), graphene.String)
+
+
+def test_should_small_integer_convert_int():
+    assert_column_conversion(types.SmallInteger(), graphene.Int)
+
+
+def test_should_big_integer_convert_int():
+    assert_column_conversion(types.BigInteger(), graphene.Int)
+
+
+def test_should_integer_convert_int():
+    assert_column_conversion(types.Integer(), graphene.Int)
+
+
+def test_should_integer_convert_id():
+    assert_column_conversion(types.Integer(), graphene.ID, primary_key=True)
+
+
+def test_should_boolean_convert_boolean():
+    field = assert_column_conversion(types.Boolean(), graphene.Boolean)
+
+
+def test_should_float_convert_float():
+    assert_column_conversion(types.Float(), graphene.Float)
+
+
+def test_should_numeric_convert_float():
+    assert_column_conversion(types.Numeric(), graphene.Float)
+
+
+def test_should_manytomany_convert_connectionorlist():
+    graphene_type = convert_sqlalchemy_relationship(Reporter.pets.property)
+    assert isinstance(graphene_type, ConnectionOrListField)
+    assert isinstance(graphene_type.type, SQLAlchemyModelField)
+    assert graphene_type.type.model == Pet
+
+
+def test_should_manytoone_convert_connectionorlist():
+    field = convert_sqlalchemy_relationship(Article.reporter.property)
+    assert isinstance(field, SQLAlchemyModelField)
+    assert field.model == Reporter
+
+
+def test_should_onetomany_convert_model():
+    graphene_type = convert_sqlalchemy_relationship(Reporter.articles.property)
+    assert isinstance(graphene_type, ConnectionOrListField)
+    assert isinstance(graphene_type.type, SQLAlchemyModelField)
+    assert graphene_type.type.model == Article

graphene/contrib/sqlalchemy/tests/test_query.py

@@ -0,0 +1,141 @@
+from py.test import raises
+
+import graphene
+from graphene import relay
+from graphene.contrib.sqlalchemy import SQLAlchemyNode, SQLAlchemyObjectType
+from .models import Article, Reporter
+
+
+def test_should_query_only_fields():
+    with raises(Exception):
+        class ReporterType(SQLAlchemyObjectType):
+
+            class Meta:
+                model = Reporter
+                only_fields = ('articles', )
+
+        schema = graphene.Schema(query=ReporterType)
+        query = '''
+            query ReporterQuery {
+              articles
+            }
+        '''
+        result = schema.execute(query)
+        assert not result.errors
+
+
+def test_should_query_well():
+    class ReporterType(SQLAlchemyObjectType):
+
+        class Meta:
+            model = Reporter
+
+    class Query(graphene.ObjectType):
+        reporter = graphene.Field(ReporterType)
+
+        def resolve_reporter(self, *args, **kwargs):
+            return ReporterType(Reporter(first_name='ABA', last_name='X'))
+
+    query = '''
+        query ReporterQuery {
+          reporter {
+            firstName,
+            lastName,
+            email
+          }
+        }
+    '''
+    expected = {
+        'reporter': {
+            'firstName': 'ABA',
+            'lastName': 'X',
+            'email': None
+        }
+    }
+    schema = graphene.Schema(query=Query)
+    result = schema.execute(query)
+    assert not result.errors
+    assert result.data == expected
+
+
+def test_should_node():
+    class ReporterNode(SQLAlchemyNode):
+
+        class Meta:
+            model = Reporter
+            exclude_fields = ('id', )
+
+        @classmethod
+        def get_node(cls, id, info):
+            return ReporterNode(Reporter(id=2, first_name='Cookie Monster'))
+
+        def resolve_articles(self, *args, **kwargs):
+            return [ArticleNode(Article(headline='Hi!'))]
+
+    class ArticleNode(SQLAlchemyNode):
+
+        class Meta:
+            model = Article
+            exclude_fields = ('id', )
+
+        @classmethod
+        def get_node(cls, id, info):
+            return ArticleNode(Article(id=1, headline='Article node'))
+
+    class Query(graphene.ObjectType):
+        node = relay.NodeField()
+        reporter = graphene.Field(ReporterNode)
+        article = graphene.Field(ArticleNode)
+
+        def resolve_reporter(self, *args, **kwargs):
+            return ReporterNode(Reporter(id=1, first_name='ABA', last_name='X'))
+
+    query = '''
+        query ReporterQuery {
+          reporter {
+            id,
+            firstName,
+            articles {
+              edges {
+                node {
+                  headline
+                }
+              }
+            }
+            lastName,
+            email
+          }
+          myArticle: node(id:"QXJ0aWNsZU5vZGU6MQ==") {
+            id
+            ... on ReporterNode {
+                firstName
+            }
+            ... on ArticleNode {
+                headline
+            }
+          }
+        }
+    '''
+    expected = {
+        'reporter': {
+            'id': 'UmVwb3J0ZXJOb2RlOjE=',
+            'firstName': 'ABA',
+            'lastName': 'X',
+            'email': None,
+            'articles': {
+                'edges': [{
+                  'node': {
+                      'headline': 'Hi!'
+                  }
+                }]
+            },
+        },
+        'myArticle': {
+            'id': 'QXJ0aWNsZU5vZGU6MQ==',
+            'headline': 'Article node'
+        }
+    }
+    schema = graphene.Schema(query=Query)
+    result = schema.execute(query)
+    assert not result.errors
+    assert result.data == expected

graphene/contrib/sqlalchemy/tests/test_schema.py

@@ -0,0 +1,45 @@
+from py.test import raises
+
+from graphene.contrib.sqlalchemy import SQLAlchemyObjectType
+from tests.utils import assert_equal_lists
+
+from .models import Reporter
+
+
+def test_should_raise_if_no_model():
+    with raises(Exception) as excinfo:
+        class Character1(SQLAlchemyObjectType):
+            pass
+    assert 'model in the Meta' in str(excinfo.value)
+
+
+def test_should_raise_if_model_is_invalid():
+    with raises(Exception) as excinfo:
+        class Character2(SQLAlchemyObjectType):
+
+            class Meta:
+                model = 1
+    assert 'not a SQLAlchemy model' in str(excinfo.value)
+
+
+def test_should_map_fields_correctly():
+    class ReporterType2(SQLAlchemyObjectType):
+
+        class Meta:
+            model = Reporter
+    assert_equal_lists(
+        ReporterType2._meta.fields_map.keys(),
+        ['articles', 'first_name', 'last_name', 'email', 'pets', 'id']
+    )
+
+
+def test_should_map_only_few_fields():
+    class Reporter2(SQLAlchemyObjectType):
+
+        class Meta:
+            model = Reporter
+            only_fields = ('id', 'email')
+    assert_equal_lists(
+        Reporter2._meta.fields_map.keys(),
+        ['id', 'email']
+    )

graphene/contrib/sqlalchemy/tests/test_types.py

@@ -0,0 +1,106 @@
+from graphql.core.type import GraphQLInterfaceType, GraphQLObjectType
+from pytest import raises
+
+from graphene import Schema
+from graphene.contrib.sqlalchemy.types import SQLAlchemyInterface, SQLAlchemyNode
+from graphene.core.fields import Field
+from graphene.core.types.scalars import Int
+from graphene.relay.fields import GlobalIDField
+from tests.utils import assert_equal_lists
+
+from .models import Article, Reporter
+
+schema = Schema()
+
+
+class Character(SQLAlchemyInterface):
+    '''Character description'''
+    class Meta:
+        model = Reporter
+
+
+@schema.register
+class Human(SQLAlchemyNode):
+    '''Human description'''
+
+    pub_date = Int()
+
+    class Meta:
+        model = Article
+        exclude_fields = ('id', )
+
+
+def test_sqlalchemy_interface():
+    assert SQLAlchemyNode._meta.is_interface is True
+
+
+def test_sqlalchemy_get_node(get):
+    human = Human.get_node(1, None)
+    get.assert_called_with(id=1)
+    assert human.id == 1
+
+
+def test_pseudo_interface_registered():
+    object_type = schema.T(Character)
+    assert Character._meta.is_interface is True
+    assert isinstance(object_type, GraphQLInterfaceType)
+    assert Character._meta.model == Reporter
+    assert_equal_lists(
+        object_type.get_fields().keys(),
+        ['articles', 'firstName', 'lastName', 'email', 'pets', 'id']
+    )
+
+
+def test_sqlalchemynode_idfield():
+    idfield = SQLAlchemyNode._meta.fields_map['id']
+    assert isinstance(idfield, GlobalIDField)
+
+
+def test_node_idfield():
+    idfield = Human._meta.fields_map['id']
+    assert isinstance(idfield, GlobalIDField)
+
+
+def test_node_replacedfield():
+    idfield = Human._meta.fields_map['pub_date']
+    assert isinstance(idfield, Field)
+    assert schema.T(idfield).type == schema.T(Int())
+
+
+def test_interface_resolve_type():
+    resolve_type = Character.resolve_type(schema, Human())
+    assert isinstance(resolve_type, GraphQLObjectType)
+
+
+def test_interface_objecttype_init_none():
+    h = Human()
+    assert h._root is None
+
+
+def test_interface_objecttype_init_good():
+    instance = Article()
+    h = Human(instance)
+    assert h._root == instance
+
+
+def test_interface_objecttype_init_unexpected():
+    with raises(AssertionError) as excinfo:
+        Human(object())
+    assert str(excinfo.value) == "Human received a non-compatible instance (object) when expecting Article"
+
+
+def test_object_type():
+    object_type = schema.T(Human)
+    Human._meta.fields_map
+    assert Human._meta.is_interface is False
+    assert isinstance(object_type, GraphQLObjectType)
+    assert_equal_lists(
+        object_type.get_fields().keys(),
+        ['headline', 'id', 'reporter', 'reporterId', 'pubDate']
+    )
+    assert schema.T(SQLAlchemyNode) in object_type.get_interfaces()
+
+
+def test_node_notinterface():
+    assert Human._meta.is_interface is False
+    assert SQLAlchemyNode in Human._meta.interfaces

graphene/contrib/sqlalchemy/types.py

@@ -1,13 +1,11 @@
 import six
 from sqlalchemy.inspection import inspect
 
-from graphene.contrib.sqlalchemy.converter import convert_sqlalchemy_column,
-    convert_sqlalchemy_relationship
-from graphene.contrib.sqlalchemy.options import SQLAlchemyOptions
-from graphene.contrib.sqlalchemy.utils import get_reverse_columns
-from graphene.core.types import BaseObjectType, ObjectTypeMeta
-from graphene.relay.fields import GlobalIDField
-from graphene.relay.types import BaseNode
+from ...core.types import BaseObjectType, ObjectTypeMeta
+from ...relay.fields import GlobalIDField
+from ...relay.types import BaseNode
+from .converter import convert_sqlalchemy_column, convert_sqlalchemy_relationship
+from .options import SQLAlchemyOptions
 
 
 class SQLAlchemyObjectTypeMeta(ObjectTypeMeta):
@@ -17,26 +15,60 @@ class SQLAlchemyObjectTypeMeta(ObjectTypeMeta):
         return SQLAlchemyInterface in parents
 
     def add_extra_fields(cls):
-        if not cls._meta.table:
+        if not cls._meta.model:
             return
-        inspected_table = inspect(cls._meta.table)
-        # Get all the columns for the relationships on the table
-        for relationship in inspected_table.relationships:
+        only_fields = cls._meta.only_fields
+        exclude_fields = cls._meta.exclude_fields
+        already_created_fields = {f.attname for f in cls._meta.local_fields}
+        inspected_model = inspect(cls._meta.model)
+
+        # Get all the columns for the relationships on the model
+        for relationship in inspected_model.relationships:
+            is_not_in_only = only_fields and relationship.key not in only_fields
+            is_already_created = relationship.key in already_created_fields
+            is_excluded = relationship.key in exclude_fields or is_already_created
+            if is_not_in_only or is_excluded:
+                # We skip this field if we specify only_fields and is not
+                # in there. Or when we excldue this field in exclude_fields
+                continue
             converted_relationship = convert_sqlalchemy_relationship(relationship)
             cls.add_to_class(relationship.key, converted_relationship)
-        for column in inspected_table.columns:
+
+        for column in inspected_model.columns:
+            is_not_in_only = only_fields and column.name not in only_fields
+            is_already_created = column.name in already_created_fields
+            is_excluded = column.name in exclude_fields or is_already_created
+            if is_not_in_only or is_excluded:
+                # We skip this field if we specify only_fields and is not
+                # in there. Or when we excldue this field in exclude_fields
+                continue
             converted_column = convert_sqlalchemy_column(column)
             cls.add_to_class(column.name, converted_column)
 
 
 class InstanceObjectType(BaseObjectType):
 
-    def __init__(self, instance=None):
-        self.instance = instance
-        super(InstanceObjectType, self).__init__()
+    def __init__(self, _root=None):
+        if _root:
+            assert isinstance(_root, self._meta.model), (
+                '{} received a non-compatible instance ({}) '
+                'when expecting {}'.format(
+                    self.__class__.__name__,
+                    _root.__class__.__name__,
+                    self._meta.model.__name__
+                ))
+        super(InstanceObjectType, self).__init__(_root=_root)
+
+    @property
+    def instance(self):
+        return self._root
+
+    @instance.setter
+    def instance(self, value):
+        self._root = value
 
     def __getattr__(self, attr):
-        return getattr(self.instance, attr)
+        return getattr(self._root, attr)
 
 
 class SQLAlchemyObjectType(six.with_metaclass(SQLAlchemyObjectTypeMeta, InstanceObjectType)):
@@ -51,6 +83,9 @@ class SQLAlchemyNode(BaseNode, SQLAlchemyInterface):
     id = GlobalIDField()
 
     @classmethod
-    def get_node(cls, id):
-        instance = cls._meta.table.objects.filter(id=id).first()
-        return cls(instance)
+    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

graphene/contrib/sqlalchemy/utils.py

@@ -1,10 +1,3 @@
-from django.db import models
-from django.db.models.manager import Manager
-from django.db.models.query import QuerySet
-
-from graphene.utils import LazyMap
-
-
 def get_type_for_model(schema, model):
     schema = schema
     types = schema.types.values()
@@ -13,11 +6,3 @@ def get_type_for_model(schema, model):
             _type._meta, 'model', None)
         if model == type_model:
             return _type
-
-
-def lazy_map(value, func):
-    if isinstance(value, Manager):
-        value = value.get_queryset()
-    if isinstance(value, QuerySet):
-        return LazyMap(value, func)
-    return value