Merge pull request #176 from graphql-python/features/middlewares

Added Middleware

docs/config.toml

@@ -17,6 +17,7 @@ ga = "UA-12613282-7"
     "/docs/basic-types/",
     "/docs/enums/",
     "/docs/relay/",
+    "/docs/middleware/",
   ]
 
 [docs.django]

docs/pages/docs/django/debug.md

@@ -13,14 +13,19 @@ For that, you will need to add the plugin in your graphene schema.
 
 ## Installation
 
-For use the Django Debug plugin in Graphene, just import `DjangoDebugPlugin` and add it to the `plugins` argument when you initiate the `Schema`.
+For use the Django Debug plugin in Graphene:
+* Import `DjangoDebugMiddleware` and add it to the `middleware` argument when you initiate the `Schema`.
+* Add the `debug` field into the schema root `Query` with the value `graphene.Field(DjangoDebug, name='__debug')`.
 
 
 ```python
-from graphene.contrib.django.debug import DjangoDebugPlugin
+from graphene.contrib.django.debug import DjangoDebugMiddleware, DjangoDebug
 
-# ...
+class Query(graphene.ObjectType):
-schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
+    # ...
+    debug = graphene.Field(DjangoDebug, name='__debug')
+
+schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
 ```
 
 This plugin, will add another field in the `Query` named `__debug`.

docs/pages/docs/middleware.md

@@ -0,0 +1,43 @@
+---
+title: Middleware
+description: Walkthrough Middleware
+---
+
+# Middleware
+
+You can use _middleware_ to affect the evaluation of fields in your schema.
+
+A middleware is any object that responds to `resolve(*args, next_middleware)`. Inside that method, it should either:
+
+* Send `resolve` to the next middleware to continue the evaluation; or
+* Return a value to end the evaluation early.
+
+Middlewares' `resolve` is invoked with several arguments:
+
+* `next` represents the execution chain. Call `next` to continue evalution.
+* `root` is the root value object passed throughout the query
+* `args` is the hash of arguments passed to the field
+* `context` is the context object passed throughout the query
+* `info` is the resolver info
+
+Add a middleware to a schema by adding to the `middlewares` list.
+
+
+### Example: Authorization
+
+This middleware only continues evaluation if the `field_name` is not `'user'`:
+
+```python
+class AuthorizationMiddleware(object):
+
+    def resolve(self, next, root, args, context, info):
+        if info.field_name == 'user':
+            return None
+        return next(root, args, context, info)
+```
+
+Then, add the middleware to your schema:
+
+```python
+schema = Schema(middlewares=[AuthorizationMiddleware])
+```

graphene/contrib/django/debug/__init__.py

@@ -1,4 +1,4 @@
-from .plugin import DjangoDebugPlugin
+from .middleware import DjangoDebugMiddleware
 from .types import DjangoDebug
 
-__all__ = ['DjangoDebugPlugin', 'DjangoDebug']
+__all__ = ['DjangoDebugMiddleware', 'DjangoDebug']

graphene/contrib/django/debug/middleware.py

@@ -0,0 +1,56 @@
+from promise import Promise
+from django.db import connections
+
+from .sql.tracking import unwrap_cursor, wrap_cursor
+from .types import DjangoDebug
+
+
+class DjangoDebugContext(object):
+
+    def __init__(self):
+        self.debug_promise = None
+        self.promises = []
+        self.enable_instrumentation()
+        self.object = DjangoDebug(sql=[])
+
+    def get_debug_promise(self):
+        if not self.debug_promise:
+            self.debug_promise = Promise.all(self.promises)
+        return self.debug_promise.then(self.on_resolve_all_promises)
+
+    def on_resolve_all_promises(self, values):
+        self.disable_instrumentation()
+        return self.object
+
+    def add_promise(self, promise):
+        if self.debug_promise and not self.debug_promise.is_fulfilled:
+            self.promises.append(promise)
+
+    def enable_instrumentation(self):
+        # This is thread-safe because database connections are thread-local.
+        for connection in connections.all():
+            wrap_cursor(connection, self)
+
+    def disable_instrumentation(self):
+        for connection in connections.all():
+            unwrap_cursor(connection)
+
+
+class DjangoDebugMiddleware(object):
+
+    def resolve(self, next, root, args, context, info):
+        django_debug = getattr(context, 'django_debug', None)
+        if not django_debug:
+            if context is None:
+                raise Exception('DjangoDebug cannot be executed in None contexts')
+            try:
+                context.django_debug = DjangoDebugContext()
+            except Exception:
+                raise Exception('DjangoDebug need the context to be writable, context received: {}.'.format(
+                    context.__class__.__name__
+                ))
+        if info.schema.graphene_schema.T(DjangoDebug) == info.return_type:
+            return context.django_debug.get_debug_promise()
+        promise = next(root, args, context, info)
+        context.django_debug.add_promise(promise)
+        return promise

graphene/contrib/django/debug/plugin.py

@@ -1,79 +0,0 @@
-from contextlib import contextmanager
-
-from django.db import connections
-
-from ....core.schema import GraphQLSchema
-from ....core.types import Field
-from ....plugins import Plugin
-from .sql.tracking import unwrap_cursor, wrap_cursor
-from .sql.types import DjangoDebugSQL
-from .types import DjangoDebug
-
-
-class WrappedRoot(object):
-
-    def __init__(self, root):
-        self._recorded = []
-        self._root = root
-
-    def record(self, **log):
-        self._recorded.append(DjangoDebugSQL(**log))
-
-    def debug(self):
-        return DjangoDebug(sql=self._recorded)
-
-
-class WrapRoot(object):
-
-    @property
-    def _root(self):
-        return self._wrapped_root.root
-
-    @_root.setter
-    def _root(self, value):
-        self._wrapped_root = value
-
-    def resolve_debug(self, args, info):
-        return self._wrapped_root.debug()
-
-
-def debug_objecttype(objecttype):
-    return type(
-        'Debug{}'.format(objecttype._meta.type_name),
-        (WrapRoot, objecttype),
-        {'debug': Field(DjangoDebug, name='__debug')})
-
-
-class DjangoDebugPlugin(Plugin):
-
-    def enable_instrumentation(self, wrapped_root):
-        # This is thread-safe because database connections are thread-local.
-        for connection in connections.all():
-            wrap_cursor(connection, wrapped_root)
-
-    def disable_instrumentation(self):
-        for connection in connections.all():
-            unwrap_cursor(connection)
-
-    def wrap_schema(self, schema_type):
-        query = schema_type._query
-        if query:
-            class_type = self.schema.objecttype(schema_type.get_query_type())
-            assert class_type, 'The query in schema is not constructed with graphene'
-            _type = debug_objecttype(class_type)
-            self.schema.register(_type, force=True)
-            return GraphQLSchema(
-                self.schema,
-                self.schema.T(_type),
-                schema_type.get_mutation_type(),
-                schema_type.get_subscription_type()
-            )
-        return schema_type
-
-    @contextmanager
-    def context_execution(self, executor):
-        executor['root_value'] = WrappedRoot(root=executor.get('root_value'))
-        executor['schema'] = self.wrap_schema(executor['schema'])
-        self.enable_instrumentation(executor['root_value'])
-        yield executor
-        self.disable_instrumentation()

graphene/contrib/django/debug/sql/tracking.py

@@ -8,6 +8,8 @@ from time import time
 from django.utils import six
 from django.utils.encoding import force_text
 
+from .types import DjangoDebugSQL, DjangoDebugPostgreSQL
+
 
 class SQLQueryTriggered(Exception):
     """Thrown when template panel triggers a query"""
@@ -139,9 +141,11 @@ class NormalCursorWrapper(object):
                     'iso_level': iso_level,
                     'encoding': conn.encoding,
                 })
-
+                _sql = DjangoDebugPostgreSQL(**params)
+            else:
+                _sql = DjangoDebugSQL(**params)
             # We keep `sql` to maintain backwards compatibility
-            self.logger.record(**params)
+            self.logger.object.sql.append(_sql)
 
     def callproc(self, procname, params=()):
         return self._record(self.cursor.callproc, procname, params)

graphene/contrib/django/debug/sql/types.py

@@ -1,7 +1,7 @@
 from .....core import Boolean, Float, ObjectType, String
 
 
-class DjangoDebugSQL(ObjectType):
+class DjangoDebugBaseSQL(ObjectType):
     vendor = String()
     alias = String()
     sql = String()
@@ -13,6 +13,12 @@ class DjangoDebugSQL(ObjectType):
     is_slow = Boolean()
     is_select = Boolean()
 
+
+class DjangoDebugSQL(DjangoDebugBaseSQL):
+    pass
+
+
+class DjangoDebugPostgreSQL(DjangoDebugBaseSQL):
     trans_id = String()
     trans_status = String()
     iso_level = String()

graphene/contrib/django/debug/tests/test_query.py

@@ -5,7 +5,12 @@ from graphene.contrib.django import DjangoConnectionField, DjangoNode
 from graphene.contrib.django.utils import DJANGO_FILTER_INSTALLED
 
 from ...tests.models import Reporter
-from ..plugin import DjangoDebugPlugin
+from ..middleware import DjangoDebugMiddleware
+from ..types import DjangoDebug
+
+
+class context(object):
+    pass
 
 # from examples.starwars_django.models import Character
 
@@ -25,6 +30,7 @@ def test_should_query_field():
 
     class Query(graphene.ObjectType):
         reporter = graphene.Field(ReporterType)
+        debug = graphene.Field(DjangoDebug, name='__debug')
 
         def resolve_reporter(self, *args, **kwargs):
             return Reporter.objects.first()
@@ -51,8 +57,8 @@ def test_should_query_field():
             }]
         }
     }
-    schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
+    schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
-    result = schema.execute(query)
+    result = schema.execute(query, context_value=context())
     assert not result.errors
     assert result.data == expected
 
@@ -70,6 +76,7 @@ def test_should_query_list():
 
     class Query(graphene.ObjectType):
         all_reporters = ReporterType.List()
+        debug = graphene.Field(DjangoDebug, name='__debug')
 
         def resolve_all_reporters(self, *args, **kwargs):
             return Reporter.objects.all()
@@ -98,8 +105,8 @@ def test_should_query_list():
             }]
         }
     }
-    schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
+    schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
-    result = schema.execute(query)
+    result = schema.execute(query, context_value=context())
     assert not result.errors
     assert result.data == expected
 
@@ -117,6 +124,7 @@ def test_should_query_connection():
 
     class Query(graphene.ObjectType):
         all_reporters = DjangoConnectionField(ReporterType)
+        debug = graphene.Field(DjangoDebug, name='__debug')
 
         def resolve_all_reporters(self, *args, **kwargs):
             return Reporter.objects.all()
@@ -146,8 +154,8 @@ def test_should_query_connection():
             }]
         },
     }
-    schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
+    schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
-    result = schema.execute(query)
+    result = schema.execute(query, context_value=context())
     assert not result.errors
     assert result.data['allReporters'] == expected['allReporters']
     assert 'COUNT' in result.data['__debug']['sql'][0]['rawSql']
@@ -172,6 +180,7 @@ def test_should_query_connectionfilter():
 
     class Query(graphene.ObjectType):
         all_reporters = DjangoFilterConnectionField(ReporterType)
+        debug = graphene.Field(DjangoDebug, name='__debug')
 
         def resolve_all_reporters(self, *args, **kwargs):
             return Reporter.objects.all()
@@ -201,8 +210,8 @@ def test_should_query_connectionfilter():
             }]
         },
     }
-    schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
+    schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
-    result = schema.execute(query)
+    result = schema.execute(query, context_value=context())
     assert not result.errors
     assert result.data['allReporters'] == expected['allReporters']
     assert 'COUNT' in result.data['__debug']['sql'][0]['rawSql']

graphene/contrib/django/debug/types.py

@@ -1,7 +1,7 @@
 from ....core.classtypes.objecttype import ObjectType
 from ....core.types import Field
-from .sql.types import DjangoDebugSQL
+from .sql.types import DjangoDebugBaseSQL
 
 
 class DjangoDebug(ObjectType):
-    sql = Field(DjangoDebugSQL.List())
+    sql = Field(DjangoDebugBaseSQL.List())

graphene/core/schema.py

@@ -7,7 +7,7 @@ from graphql.utils.schema_printer import print_schema
 
 from graphene import signals
 
-from ..plugins import CamelCase, PluginManager
+from ..middlewares import MiddlewareManager, CamelCaseArgsMiddleware
 from .classtypes.base import ClassType
 from .types.base import InstanceType
 
@@ -23,7 +23,7 @@ class Schema(object):
     _executor = None
 
     def __init__(self, query=None, mutation=None, subscription=None,
-                 name='Schema', executor=None, plugins=None, auto_camelcase=True, **options):
+                 name='Schema', executor=None, middlewares=None, auto_camelcase=True, **options):
         self._types_names = {}
         self._types = {}
         self.mutation = mutation
@@ -31,21 +31,19 @@ class Schema(object):
         self.subscription = subscription
         self.name = name
         self.executor = executor
-        plugins = plugins or []
+        if 'plugins' in options:
+            raise Exception('Plugins are deprecated, please use middlewares.')
+        middlewares = middlewares or []
         if auto_camelcase:
-            plugins.append(CamelCase())
+            middlewares.append(CamelCaseArgsMiddleware())
-        self.plugins = PluginManager(self, plugins)
+        self.auto_camelcase = auto_camelcase
+        self.middleware_manager = MiddlewareManager(self, middlewares)
         self.options = options
         signals.init_schema.send(self)
 
     def __repr__(self):
         return '<Schema: %s (%s)>' % (str(self.name), hash(self))
 
-    def __getattr__(self, name):
-        if name in self.plugins:
-            return getattr(self.plugins, name)
-        return super(Schema, self).__getattr__(name)
-
     def T(self, _type):
         if not _type:
             return
@@ -111,13 +109,16 @@ class Schema(object):
             raise KeyError('Type %r not found in %r' % (type_name, self))
         return self._types_names[type_name]
 
+    def resolver_with_middleware(self, resolver):
+        return self.middleware_manager.wrap(resolver)
+
     @property
     def types(self):
         return self._types_names
 
     def execute(self, request_string='', root_value=None, variable_values=None,
                 context_value=None, operation_name=None, executor=None):
-        kwargs = dict(
+        return graphql(
             schema=self.schema,
             request_string=request_string,
             root_value=root_value,
@@ -126,8 +127,6 @@ class Schema(object):
             operation_name=operation_name,
             executor=executor or self._executor
         )
-        with self.plugins.context_execution(**kwargs) as execute_kwargs:
-            return graphql(**execute_kwargs)
 
     def introspect(self):
         return graphql(self.schema, introspection_query).data

graphene/core/tests/test_old_fields.py

@@ -93,7 +93,7 @@ def test_field_resolve():
     f = StringField(required=True, resolve=lambda *args: 'RESOLVED').as_field()
     f.contribute_to_class(MyOt, 'field_name')
     field_type = schema.T(f)
-    assert 'RESOLVED' == field_type.resolver(MyOt, None, None, None)
+    assert 'RESOLVED' == field_type.resolver(MyOt, None, None, None).value
 
 
 def test_field_resolve_type_custom():

graphene/core/tests/test_schema.py

@@ -154,6 +154,12 @@ def test_lazytype():
     assert schema.T(t) == schema.T(MyType)
 
 
+def test_deprecated_plugins_throws_exception():
+    with raises(Exception) as excinfo:
+        Schema(plugins=[])
+    assert 'Plugins are deprecated, please use middlewares' in str(excinfo.value)
+
+
 def test_schema_str():
     expected = """
 schema {

graphene/core/types/argument.py

@@ -1,9 +1,7 @@
-from functools import wraps
 from itertools import chain
 
 from graphql.type import GraphQLArgument
 
-from ...utils import ProxySnakeDict
 from .base import ArgumentType, GroupNamedType, NamedType, OrderedType
 
 
@@ -53,11 +51,3 @@ def to_arguments(*args, **kwargs):
         arguments[name] = argument
 
     return sorted(arguments.values())
-
-
-def snake_case_args(resolver):
-    @wraps(resolver)
-    def wrapped_resolver(instance, args, context, info):
-        return resolver(instance, ProxySnakeDict(args), context, info)
-
-    return wrapped_resolver

graphene/core/types/base.py

@@ -3,6 +3,8 @@ from functools import partial, total_ordering
 
 import six
 
+from ...utils import to_camel_case
+
 
 class InstanceType(object):
 
@@ -142,7 +144,9 @@ class GroupNamedType(InstanceType):
         self.types = types
 
     def get_named_type(self, schema, type):
-        name = type.name or schema.get_default_namedtype_name(type.default_name)
+        name = type.name
+        if not name and schema.auto_camelcase:
+            name = to_camel_case(type.default_name)
         return name, schema.T(type)
 
     def iter_types(self, schema):

graphene/core/types/field.py

@@ -10,7 +10,7 @@ from ..classtypes.base import FieldsClassType
 from ..classtypes.inputobjecttype import InputObjectType
 from ..classtypes.mutation import Mutation
 from ..exceptions import SkipField
-from .argument import Argument, ArgumentsGroup, snake_case_args
+from .argument import Argument, ArgumentsGroup
 from .base import (ArgumentType, GroupNamedType, LazyType, MountType,
                    NamedType, OrderedType)
 from .definitions import NonNull
@@ -89,9 +89,6 @@ class Field(NamedType, OrderedType):
             return NonNull(self.type)
         return self.type
 
-    def decorate_resolver(self, resolver):
-        return snake_case_args(resolver)
-
     def internal_type(self, schema):
         if not self.object_type:
             raise Exception('The field is not mounted in any ClassType')
@@ -118,10 +115,13 @@ class Field(NamedType, OrderedType):
             resolver = wrapped_func
 
         assert type, 'Internal type for field %s is None' % str(self)
-        return GraphQLField(type, args=schema.T(arguments),
+        return GraphQLField(
-                            resolver=self.decorate_resolver(resolver),
+            type,
-                            deprecation_reason=self.deprecation_reason,
+            args=schema.T(arguments),
-                            description=description,)
+            resolver=schema.resolver_with_middleware(resolver),
+            deprecation_reason=self.deprecation_reason,
+            description=description,
+        )
 
     def __repr__(self):
         """
@@ -175,7 +175,8 @@ class InputField(NamedType, OrderedType):
     def internal_type(self, schema):
         return GraphQLInputObjectField(
             schema.T(self.type),
-            default_value=self.default, description=self.description)
+            default_value=self.default, description=self.description
+        )
 
 
 class FieldsGroupType(GroupNamedType):

graphene/core/types/tests/test_argument.py

@@ -4,7 +4,7 @@ from pytest import raises
 from graphene.core.schema import Schema
 from graphene.core.types import ObjectType
 
-from ..argument import Argument, snake_case_args, to_arguments
+from ..argument import Argument, to_arguments
 from ..scalars import String
 
 
@@ -45,10 +45,3 @@ def test_to_arguments_wrong_type():
             p=3
         )
     assert 'Unknown argument p=3' == str(excinfo.value)
-
-
-def test_snake_case_args():
-    def resolver(instance, args, context, info):
-        return args['my_arg']['inner_arg']
-    r = snake_case_args(resolver)
-    assert r(None, {'myArg': {'innerArg': 3}}, None, None) == 3

graphene/core/types/tests/test_field.py

@@ -24,7 +24,7 @@ def test_field_internal_type():
     assert field.attname == 'my_field'
     assert isinstance(type, GraphQLField)
     assert type.description == 'My argument'
-    assert type.resolver(None, {}, None, None) == 'RESOLVED'
+    assert type.resolver(None, {}, None, None).value == 'RESOLVED'
     assert type.type == GraphQLString
 
 
@@ -43,7 +43,7 @@ def test_field_objectype_resolver():
     type = schema.T(field)
     assert isinstance(type, GraphQLField)
     assert type.description == 'Custom description'
-    assert type.resolver(Query(), {}, None, None) == 'RESOLVED'
+    assert type.resolver(Query(), {}, None, None).value == 'RESOLVED'
 
 
 def test_field_custom_name():
@@ -161,7 +161,7 @@ def test_field_resolve_argument():
     schema = Schema(query=Query)
 
     type = schema.T(field)
-    assert type.resolver(None, {'firstName': 'Peter'}, None, None) == 'Peter'
+    assert type.resolver(None, {'firstName': 'Peter'}, None, None).value == 'Peter'
 
 
 def test_field_resolve_vars():
@@ -216,7 +216,6 @@ def test_field_resolve_object():
         att_func = field_func
 
     assert field.resolver(Root, {}, None) is True
-    assert field.resolver(Root, {}, None) is True
 
 
 def test_field_resolve_source_object():
@@ -235,4 +234,3 @@ def test_field_resolve_source_object():
         att_func = field_func
 
     assert field.resolver(Root, {}, None) is True
-    assert field.resolver(Root, {}, None) is True

graphene/middlewares/__init__.py

@@ -0,0 +1,6 @@
+from .base import MiddlewareManager
+from .camel_case import CamelCaseArgsMiddleware
+
+__all__ = [
+    'MiddlewareManager', 'CamelCaseArgsMiddleware'
+]

graphene/middlewares/base.py

@@ -0,0 +1,23 @@
+from ..utils import promise_middleware
+
+MIDDLEWARE_RESOLVER_FUNCTION = 'resolve'
+
+
+class MiddlewareManager(object):
+
+    def __init__(self, schema, middlewares=None):
+        self.schema = schema
+        self.middlewares = middlewares or []
+
+    def add_middleware(self, middleware):
+        self.middlewares.append(middleware)
+
+    def get_middleware_resolvers(self):
+        for middleware in self.middlewares:
+            if not hasattr(middleware, MIDDLEWARE_RESOLVER_FUNCTION):
+                continue
+            yield getattr(middleware, MIDDLEWARE_RESOLVER_FUNCTION)
+
+    def wrap(self, resolver):
+        middleware_resolvers = self.get_middleware_resolvers()
+        return promise_middleware(resolver, middleware_resolvers)

graphene/middlewares/camel_case.py

@@ -0,0 +1,8 @@
+from ..utils import ProxySnakeDict
+
+
+class CamelCaseArgsMiddleware(object):
+
+    def resolve(self, next, root, args, context, info):
+        args = ProxySnakeDict(args)
+        return next(root, args, context, info)

graphene/plugins/__init__.py

@@ -1,6 +0,0 @@
-from .base import Plugin, PluginManager
-from .camel_case import CamelCase
-
-__all__ = [
-    'Plugin', 'PluginManager', 'CamelCase'
-]

graphene/plugins/base.py

@@ -1,53 +0,0 @@
-from contextlib import contextmanager
-from functools import partial, reduce
-
-
-class Plugin(object):
-
-    def contribute_to_schema(self, schema):
-        self.schema = schema
-
-
-def apply_function(a, b):
-    return b(a)
-
-
-class PluginManager(object):
-
-    PLUGIN_FUNCTIONS = ('get_default_namedtype_name', )
-
-    def __init__(self, schema, plugins=[]):
-        self.schema = schema
-        self.plugins = []
-        for plugin in plugins:
-            self.add_plugin(plugin)
-
-    def add_plugin(self, plugin):
-        if hasattr(plugin, 'contribute_to_schema'):
-            plugin.contribute_to_schema(self.schema)
-        self.plugins.append(plugin)
-
-    def get_plugin_functions(self, function):
-        for plugin in self.plugins:
-            if not hasattr(plugin, function):
-                continue
-            yield getattr(plugin, function)
-
-    def __getattr__(self, name):
-        functions = self.get_plugin_functions(name)
-        return partial(reduce, apply_function, functions)
-
-    def __contains__(self, name):
-        return name in self.PLUGIN_FUNCTIONS
-
-    @contextmanager
-    def context_execution(self, **executor):
-        contexts = []
-        functions = self.get_plugin_functions('context_execution')
-        for f in functions:
-            context = f(executor)
-            executor = context.__enter__()
-            contexts.append((context, executor))
-        yield executor
-        for context, value in contexts[::-1]:
-            context.__exit__(None, None, None)

graphene/plugins/camel_case.py

@@ -1,7 +0,0 @@
-from ..utils import to_camel_case
-
-
-class CamelCase(object):
-
-    def get_default_namedtype_name(self, value):
-        return to_camel_case(value)

graphene/utils/__init__.py

@@ -3,6 +3,7 @@ from .proxy_snake_dict import ProxySnakeDict
 from .caching import cached_property, memoize
 from .maybe_func import maybe_func
 from .misc import enum_to_graphql_enum
+from .promise_middleware import promise_middleware
 from .resolve_only_args import resolve_only_args
 from .lazylist import LazyList
 from .wrap_resolver_function import with_context, wrap_resolver_function
@@ -10,5 +11,5 @@ from .wrap_resolver_function import with_context, wrap_resolver_function
 
 __all__ = ['to_camel_case', 'to_snake_case', 'to_const', 'ProxySnakeDict',
            'cached_property', 'memoize', 'maybe_func', 'enum_to_graphql_enum',
-           'resolve_only_args', 'LazyList', 'with_context',
+           'promise_middleware', 'resolve_only_args', 'LazyList', 'with_context',
            'wrap_resolver_function']

graphene/utils/promise_middleware.py

@@ -0,0 +1,17 @@
+from functools import partial
+from itertools import chain
+
+from promise import Promise
+
+
+def promise_middleware(func, middlewares):
+    middlewares = chain((func, make_it_promise), middlewares)
+    past = None
+    for m in middlewares:
+        past = partial(m, past) if past else m
+
+    return past
+
+
+def make_it_promise(next, *a, **b):
+    return Promise.resolve(next(*a, **b))