Merge branch 'master' into custom-execution-context

Author: syrusakbary

.flake8

@@ -1,2 +1,3 @@
 [flake8]
 exclude = .git,.mypy_cache,.pytest_cache,.tox,.venv,__pycache__,build,dist,docs
+max-line-length = 88

README.md

@@ -11,9 +11,9 @@ a query language for APIs created by Facebook.
 [![Dependency Updates](https://pyup.io/repos/github/graphql-python/graphql-core-next/shield.svg)](https://pyup.io/repos/github/graphql-python/graphql-core-next/)
 [![Python 3 Status](https://pyup.io/repos/github/graphql-python/graphql-core-next/python-3-shield.svg)](https://pyup.io/repos/github/graphql-python/graphql-core-next/)
 
-The current version 1.0.0 of GraphQL-core-next is up-to-date with GraphQL.js
-version 14.0.0. All parts of the API are covered by an extensive test suite of
-currently 1603 unit tests.
+The current version 1.0.1 of GraphQL-core-next is up-to-date with GraphQL.js
+version 14.0.2. All parts of the API are covered by an extensive test suite of
+currently 1614 unit tests.
 
 
 ## Documentation

docs/conf.py

@@ -61,7 +61,7 @@
 # The short X.Y version.
 version = u'1.0'
 # The full version, including alpha/beta/rc tags.
-release = u'1.0.0'
+release = u'1.0.1'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.

graphql/__init__.py

@@ -37,8 +37,8 @@
   - `graphql/subscription`: Subscribe to data updates.
 """
 
-__version__ = '1.0.0'
-__version_js__ = '14.0.0'
+__version__ = '1.0.1'
+__version_js__ = '14.0.2'
 
 # The primary entry point into fulfilling a GraphQL request.
 
@@ -260,36 +260,37 @@
 
 # Validate GraphQL queries.
 from .validation import (
-  validate,
-  ValidationContext,
-  # All validation rules in the GraphQL Specification.
-  specified_rules,
-  # Individual validation rules.
-  FieldsOnCorrectTypeRule,
-  FragmentsOnCompositeTypesRule,
-  KnownArgumentNamesRule,
-  KnownDirectivesRule,
-  KnownFragmentNamesRule,
-  KnownTypeNamesRule,
-  LoneAnonymousOperationRule,
-  NoFragmentCyclesRule,
-  NoUndefinedVariablesRule,
-  NoUnusedFragmentsRule,
-  NoUnusedVariablesRule,
-  OverlappingFieldsCanBeMergedRule,
-  PossibleFragmentSpreadsRule,
-  ProvidedRequiredArgumentsRule,
-  ScalarLeafsRule,
-  SingleFieldSubscriptionsRule,
-  UniqueArgumentNamesRule,
-  UniqueDirectivesPerLocationRule,
-  UniqueFragmentNamesRule,
-  UniqueInputFieldNamesRule,
-  UniqueOperationNamesRule,
-  UniqueVariableNamesRule,
-  ValuesOfCorrectTypeRule,
-  VariablesAreInputTypesRule,
-  VariablesInAllowedPositionRule)
+    validate,
+    ValidationContext,
+    ValidationRule, ASTValidationRule, SDLValidationRule,
+    # All validation rules in the GraphQL Specification.
+    specified_rules,
+    # Individual validation rules.
+    FieldsOnCorrectTypeRule,
+    FragmentsOnCompositeTypesRule,
+    KnownArgumentNamesRule,
+    KnownDirectivesRule,
+    KnownFragmentNamesRule,
+    KnownTypeNamesRule,
+    LoneAnonymousOperationRule,
+    NoFragmentCyclesRule,
+    NoUndefinedVariablesRule,
+    NoUnusedFragmentsRule,
+    NoUnusedVariablesRule,
+    OverlappingFieldsCanBeMergedRule,
+    PossibleFragmentSpreadsRule,
+    ProvidedRequiredArgumentsRule,
+    ScalarLeafsRule,
+    SingleFieldSubscriptionsRule,
+    UniqueArgumentNamesRule,
+    UniqueDirectivesPerLocationRule,
+    UniqueFragmentNamesRule,
+    UniqueInputFieldNamesRule,
+    UniqueOperationNamesRule,
+    UniqueVariableNamesRule,
+    ValuesOfCorrectTypeRule,
+    VariablesAreInputTypesRule,
+    VariablesInAllowedPositionRule)
 
 # Create, format, and print GraphQL errors.
 from .error import (
@@ -430,6 +431,7 @@
     'get_directive_values', 'ExecutionContext', 'ExecutionResult',
     'subscribe', 'create_source_event_stream',
     'validate', 'ValidationContext',
+    'ValidationRule', 'ASTValidationRule', 'SDLValidationRule',
     'specified_rules',
     'FieldsOnCorrectTypeRule', 'FragmentsOnCompositeTypesRule',
     'KnownArgumentNamesRule', 'KnownDirectivesRule', 'KnownFragmentNamesRule',

graphql/execution/__init__.py

@@ -6,10 +6,12 @@
 
 from .execute import (
     execute, default_field_resolver, response_path_as_list,
-    ExecutionContext, ExecutionResult)
+    ExecutionContext, ExecutionResult, Middleware)
+from .middleware import MiddlewareManager
 from .values import get_directive_values
 
 __all__ = [
     'execute', 'default_field_resolver', 'response_path_as_list',
     'ExecutionContext', 'ExecutionResult',
+    'Middleware', 'MiddlewareManager',
     'get_directive_values']

graphql/execution/execute.py

@@ -8,6 +8,7 @@
     DocumentNode, FieldNode, FragmentDefinitionNode,
     FragmentSpreadNode, InlineFragmentNode, OperationDefinitionNode,
     OperationType, SelectionSetNode)
+from .middleware import MiddlewareManager
 from ..pyutils import is_invalid, is_nullish, MaybeAwaitable
 from ..utilities import get_operation_root_type, type_from_ast
 from ..type import (
@@ -24,7 +25,7 @@
 __all__ = [
     'add_path', 'assert_valid_execution_arguments', 'default_field_resolver',
     'execute', 'get_field_def', 'response_path_as_list',
-    'ExecutionResult', 'ExecutionContext']
+    'ExecutionResult', 'ExecutionContext', 'Middleware']
 
 
 # Terminology
@@ -59,6 +60,53 @@ class ExecutionResult(NamedTuple):
 
 ExecutionResult.__new__.__defaults__ = (None, None)  # type: ignore
 
+Middleware = Optional[Union[Tuple, List, MiddlewareManager]]
+
+
+def execute(
+        schema: GraphQLSchema, document: DocumentNode,
+        root_value: Any=None, context_value: Any=None,
+        variable_values: Dict[str, Any]=None,
+        operation_name: str=None,
+        field_resolver: GraphQLFieldResolver=None,
+        execution_context_class: Type[ExecutionContext]=ExecutionContext,
+        middleware: Middleware=None
+        ) -> MaybeAwaitable[ExecutionResult]:
+    """Execute a GraphQL operation.
+
+    Implements the "Evaluating requests" section of the GraphQL specification.
+
+    Returns an ExecutionResult (if all encountered resolvers are synchronous),
+    or a coroutine object eventually yielding an ExecutionResult.
+
+    If the arguments to this function do not result in a legal execution
+    context, a GraphQLError will be thrown immediately explaining the invalid
+    input.
+    """
+    # If arguments are missing or incorrect, throw an error.
+    assert_valid_execution_arguments(schema, document, variable_values)
+
+    # If a valid execution context cannot be created due to incorrect
+    #  arguments, a "Response" with only errors is returned.
+    exe_context = execution_context_class.build(
+        schema, document, root_value, context_value,
+        variable_values, operation_name, field_resolver, middleware)
+
+    # Return early errors if execution context failed.
+    if isinstance(exe_context, list):
+        return ExecutionResult(data=None, errors=exe_context)
+
+    # Return a possible coroutine object that will eventually yield the data
+    # described by the "Response" section of the GraphQL specification.
+    #
+    # If errors are encountered while executing a GraphQL field, only that
+    # field and its descendants will be omitted, and sibling fields will still
+    # be executed. An execution which encounters errors will still result in a
+    # coroutine object that can be executed without errors.
+
+    data = exe_context.execute_operation(exe_context.operation, root_value)
+    return exe_context.build_response(data)
+
 
 class ExecutionContext:
     """Data that must be available at all points during query execution.
@@ -74,6 +122,7 @@ class ExecutionContext:
     operation: OperationDefinitionNode
     variable_values: Dict[str, Any]
     field_resolver: GraphQLFieldResolver
+    middleware_manager: Optional[MiddlewareManager]
     errors: List[GraphQLError]
 
     def __init__(
@@ -83,6 +132,7 @@ def __init__(
             operation: OperationDefinitionNode,
             variable_values: Dict[str, Any],
             field_resolver: GraphQLFieldResolver,
+            middleware_manager: Optional[MiddlewareManager],
             errors: List[GraphQLError]) -> None:
         self.schema = schema
         self.fragments = fragments
@@ -91,6 +141,7 @@ def __init__(
         self.operation = operation
         self.variable_values = variable_values
         self.field_resolver = field_resolver  # type: ignore
+        self.middleware_manager = middleware_manager
         self.errors = errors
         self._subfields_cache: Dict[
             Tuple[GraphQLObjectType, Tuple[FieldNode, ...]],
@@ -102,7 +153,8 @@ def build(
             root_value: Any=None, context_value: Any=None,
             raw_variable_values: Dict[str, Any]=None,
             operation_name: str=None,
-            field_resolver: GraphQLFieldResolver=None
+            field_resolver: GraphQLFieldResolver=None,
+            middleware: Middleware=None
             ) -> Union[List[GraphQLError], 'ExecutionContext']:
         """Build an execution context
 
@@ -115,6 +167,18 @@ def build(
         operation: Optional[OperationDefinitionNode] = None
         has_multiple_assumed_operations = False
         fragments: Dict[str, FragmentDefinitionNode] = {}
+        middleware_manager: Optional[MiddlewareManager] = None
+        if middleware is not None:
+            if isinstance(middleware, (list, tuple)):
+                middleware_manager = MiddlewareManager(*middleware)
+            elif isinstance(middleware, MiddlewareManager):
+                middleware_manager = middleware
+            else:
+                raise TypeError(
+                    "Middleware must be passed as a list or tuple of functions"
+                    " or objects, or as a single MiddlewareManager object."
+                    f" Got {middleware!r} instead.")
+
         for definition in document.definitions:
             if isinstance(definition, OperationDefinitionNode):
                 if not operation_name and operation:
@@ -159,7 +223,8 @@ def build(
 
         return cls(
             schema, fragments, root_value, context_value, operation,
-            variable_values, field_resolver or default_field_resolver, errors)
+            variable_values, field_resolver or default_field_resolver,
+            middleware_manager, errors)
 
     def build_response(
         self, data: MaybeAwaitable[Optional[Dict[str, Any]]]
@@ -405,6 +470,9 @@ def resolve_field(
 
         resolve_fn = field_def.resolve or self.field_resolver
 
+        if self.middleware_manager:
+            resolve_fn = self.middleware_manager.get_field_resolver(resolve_fn)
+
         info = self.build_resolve_info(
             field_def, field_nodes, parent_type, path)
 
@@ -752,49 +820,6 @@ def collect_subfields(
         return sub_field_nodes
 
 
-def execute(
-        schema: GraphQLSchema, document: DocumentNode,
-        root_value: Any=None, context_value: Any=None,
-        variable_values: Dict[str, Any]=None,
-        operation_name: str=None, field_resolver: GraphQLFieldResolver=None,
-        execution_context_class: Type[ExecutionContext]=ExecutionContext,
-        ) -> MaybeAwaitable[ExecutionResult]:
-    """Execute a GraphQL operation.
-
-    Implements the "Evaluating requests" section of the GraphQL specification.
-
-    Returns an ExecutionResult (if all encountered resolvers are synchronous),
-    or a coroutine object eventually yielding an ExecutionResult.
-
-    If the arguments to this function do not result in a legal execution
-    context, a GraphQLError will be thrown immediately explaining the invalid
-    input.
-    """
-    # If arguments are missing or incorrect, throw an error.
-    assert_valid_execution_arguments(schema, document, variable_values)
-
-    # If a valid execution context cannot be created due to incorrect
-    #  arguments, a "Response" with only errors is returned.
-    exe_context = execution_context_class.build(
-        schema, document, root_value, context_value,
-        variable_values, operation_name, field_resolver)
-
-    # Return early errors if execution context failed.
-    if isinstance(exe_context, list):
-        return ExecutionResult(data=None, errors=exe_context)
-
-    # Return a possible coroutine object that will eventually yield the data
-    # described by the "Response" section of the GraphQL specification.
-    #
-    # If errors are encountered while executing a GraphQL field, only that
-    # field and its descendants will be omitted, and sibling fields will still
-    # be executed. An execution which encounters errors will still result in a
-    # coroutine object that can be executed without errors.
-
-    data = exe_context.execute_operation(exe_context.operation, root_value)
-    return exe_context.build_response(data)
-
-
 def assert_valid_execution_arguments(
         schema: GraphQLSchema, document: DocumentNode,
         raw_variable_values: Dict[str, Any]=None) -> None:

graphql/execution/middleware.py

@@ -0,0 +1,74 @@
+from functools import partial
+from inspect import isfunction
+from itertools import chain
+
+from typing import (
+    Callable, Iterator, Dict, Tuple, Any, Iterable, Optional, cast)
+
+__all__ = ['MiddlewareManager']
+
+GraphQLFieldResolver = Callable[..., Any]
+
+
+class MiddlewareManager:
+    """Manager for the middleware chain.
+
+    This class helps to wrap resolver functions with the provided middleware
+    functions and/or objects. The functions take the next middleware function
+    as first argument. If middleware is provided as an object, it must provide
+    a method 'resolve' that is used as the middleware function.
+    """
+
+    __slots__ = 'middlewares', '_middleware_resolvers', '_cached_resolvers'
+
+    _cached_resolvers: Dict[GraphQLFieldResolver, GraphQLFieldResolver]
+    _middleware_resolvers: Optional[Iterator[Callable]]
+
+    def __init__(self, *middlewares: Any) -> None:
+        self.middlewares = middlewares
+        self._middleware_resolvers = get_middleware_resolvers(
+            middlewares) if middlewares else None
+        self._cached_resolvers = {}
+
+    def get_field_resolver(
+            self, field_resolver: GraphQLFieldResolver
+            ) -> GraphQLFieldResolver:
+        """Wrap the provided resolver with the middleware.
+
+        Returns a function that chains the middleware functions with the
+        provided resolver function
+        """
+        if self._middleware_resolvers is None:
+            return field_resolver
+        if field_resolver not in self._cached_resolvers:
+            self._cached_resolvers[field_resolver] = middleware_chain(
+                field_resolver, self._middleware_resolvers)
+        return self._cached_resolvers[field_resolver]
+
+
+def get_middleware_resolvers(
+        middlewares: Tuple[Any, ...]) -> Iterator[Callable]:
+    """Get a list of resolver functions from a list of classes or functions."""
+    for middleware in middlewares:
+        if isfunction(middleware):
+            yield middleware
+        else:  # middleware provided as object with 'resolve' method
+            resolver_func = getattr(middleware, 'resolve', None)
+            if resolver_func is not None:
+                yield resolver_func
+
+
+def middleware_chain(
+        func: GraphQLFieldResolver, middlewares: Iterable[Callable]
+        ) -> GraphQLFieldResolver:
+    """Chain the given function with the provided middlewares.
+
+    Returns a new resolver function that is the chain of both.
+    """
+    if not middlewares:
+        return func
+    middlewares = chain((func,), middlewares)
+    last_func: Optional[GraphQLFieldResolver] = None
+    for middleware in middlewares:
+        last_func = partial(middleware, last_func) if last_func else middleware
+    return cast(GraphQLFieldResolver, last_func)