Adding support for sqlalchemy

Author: Jeremy Feinstein

graphene/contrib/sqlalchemy/__init__.py

@@ -0,0 +1,12 @@
+from graphene.contrib.sqlalchemy.types import (
+    SQLAlchemyObjectType,
+    SQLAlchemyInterface,
+    SQLAlchemyNode
+)
+from graphene.contrib.sqlalchemy.fields import (
+    SQLAlchemyConnectionField,
+    SQLAlchemyModelField
+)
+
+__all__ = ['SQLAlchemyObjectType', 'SQLAlchemyInterface', 'SQLAlchemyNode',
+           'SQLAlchemyConnectionField', 'SQLAlchemyModelField']

graphene/contrib/sqlalchemy/converter.py

@@ -0,0 +1,61 @@
+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
+
+
+def convert_sqlalchemy_relationship(relationship):
+    model_field = SQLAlchemyModelField(field.table, description=relationship.key)
+    if relationship.direction == interfaces.ONETOMANY:
+        return model_field
+    elif (relationship.direction == interfaces.MANYTOONE or
+          relationship.direction == interfaces.MANYTOMANY):
+        return ConnectionOrListField(model_field)
+
+
+def convert_sqlalchemy_column(column):
+    try:
+        return convert_sqlalchemy_type(column.type, column)
+    except Exception:
+        raise
+
+
+@singledispatch
+def convert_sqlalchemy_type():
+    raise Exception(
+        "Don't know how to convert the SQLAlchemy column %s (%s)" % (column, column.__class__))
+
+
+@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.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)
+
+
+@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):
+    if column.primary_key:
+        return IDField(description=column.description)
+    else:
+        return IntField(description=column.description)
+
+
+@convert_sqlalchemy_type.register(types.Boolean)
+def convert_column_to_boolean(column):
+    return BooleanField(description=column.description)
+
+
+@convert_sqlalchemy_type.register(types.Float)
+@convert_sqlalchemy_type.register(types.Numeric)
+def convert_column_to_float(column):
+    return FloatField(description=column.description)

graphene/contrib/sqlalchemy/fields.py

@@ -0,0 +1,67 @@
+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
+
+
+class SQLAlchemyConnectionField(relay.ConnectionField):
+
+    def wrap_resolved(self, value, instance, args, info):
+        schema = info.schema.graphene_schema
+        return lazy_map(value, self.get_object_type(schema))
+
+
+class LazyListField(ListField):
+
+    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))
+
+
+class ConnectionOrListField(LazyField):
+
+    def get_field(self, schema):
+        model_field = self.field_type
+        field_object_type = model_field.get_object_type(schema)
+        if is_node(field_object_type):
+            field = SQLAlchemyConnectionField(model_field)
+        else:
+            field = LazyListField(model_field)
+        field.contribute_to_class(self.object_type, self.name)
+        return field
+
+
+class SQLAlchemyModelField(Field):
+
+    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)
+
+    def internal_type(self, schema):
+        _type = self.get_object_type(schema)
+        if not _type and self.object_type._meta.only_fields:
+            raise Exception(
+                "Model %r is not accessible by the schema. "
+                "You can either register the type manually "
+                "using @schema.register. "
+                "Or disable the field %s in %s" % (
+                    self.model,
+                    self.attname,
+                    self.object_type
+                )
+            )
+        return schema.T(_type) or Field.SKIP
+
+    def get_object_type(self, schema):
+        return get_type_for_model(schema, self.model)

graphene/contrib/sqlalchemy/options.py

@@ -0,0 +1,37 @@
+import inspect
+
+from sqlalchemy import Table
+
+from graphene.core.options import Options
+from graphene.relay.types import Node
+from graphene.relay.utils import is_node
+
+VALID_ATTRS = ('table', 'only_columns', 'exclude_columns')
+
+
+def is_base(cls):
+    from graphene.contrib.SQLAlchemy.types import SQLAlchemyObjectType
+    return SQLAlchemyObjectType in cls.__bases__
+
+
+class SQLAlchemyOptions(Options):
+
+    def __init__(self, *args, **kwargs):
+        self.table = None
+        super(SQLAlchemyOptions, self).__init__(*args, **kwargs)
+        self.valid_attrs += VALID_ATTRS
+        self.only_fields = None
+        self.exclude_fields = []
+
+    def contribute_to_class(self, cls, name):
+        super(SQLAlchemyOptions, self).contribute_to_class(cls, name)
+        if is_node(cls):
+            self.exclude_fields = list(self.exclude_fields)
+            self.interfaces.append(Node)
+        if not is_node(cls) and not is_base(cls):
+            return
+        if not self.table:
+            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)

graphene/contrib/sqlalchemy/types.py

@@ -0,0 +1,56 @@
+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
+
+
+class SQLAlchemyObjectTypeMeta(ObjectTypeMeta):
+    options_cls = SQLAlchemyOptions
+
+    def is_interface(cls, parents):
+        return SQLAlchemyInterface in parents
+
+    def add_extra_fields(cls):
+        if not cls._meta.table:
+            return
+        inspected_table = inspect(cls._meta.table)
+        # Get all the columns for the relationships on the table
+        for relationship in inspected_table.relationships:
+            converted_relationship = convert_sqlalchemy_relationship(relationship)
+            cls.add_to_class(relationship.key, converted_relationship)
+        for column in inspected_table.columns:
+            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 __getattr__(self, attr):
+        return getattr(self.instance, attr)
+
+
+class SQLAlchemyObjectType(six.with_metaclass(SQLAlchemyObjectTypeMeta, InstanceObjectType)):
+    pass
+
+
+class SQLAlchemyInterface(six.with_metaclass(SQLAlchemyObjectTypeMeta, InstanceObjectType)):
+    pass
+
+
+class SQLAlchemyNode(BaseNode, SQLAlchemyInterface):
+    id = GlobalIDField()
+
+    @classmethod
+    def get_node(cls, id):
+        instance = cls._meta.table.objects.filter(id=id).first()
+        return cls(instance)

graphene/contrib/sqlalchemy/utils.py

@@ -0,0 +1,23 @@
+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()
+    for _type in types:
+        type_model = hasattr(_type, '_meta') and getattr(
+            _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

setup.py

@@ -70,6 +70,9 @@ def run_tests(self):
             'singledispatch>=3.4.0.3',
             'graphql-django-view>=1.0.0',
         ],
+        'sqlalchemy': [
+            'SQLAlchemy'
+        ]
     },
 
     cmdclass={'test': PyTest},