Support value transformation of input object types (#42)

README.md

@@ -13,7 +13,7 @@ a query language for APIs created by Facebook.
 [![Code Style](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 
 The current version 1.0.5 of GraphQL-core-next is up-to-date with GraphQL.js version
-14.3.1. All parts of the API are covered by an extensive test suite of currently 1786
+14.3.1. All parts of the API are covered by an extensive test suite of currently 1792
 unit tests.
 
 

graphql/type/definition.py

@@ -1091,6 +1091,7 @@ def is_deprecated(self) -> bool:
 
 
 GraphQLInputFieldMap = Dict[str, "GraphQLInputField"]
+GraphQLInputFieldOutType = Callable[[Dict[str, Any]], Any]
 
 
 class GraphQLInputObjectType(GraphQLNamedType):
@@ -1113,8 +1114,13 @@ class GeoPoint(GraphQLInputObjectType):
                 'alt': GraphQLInputField(
                           GraphQLFloat(), default_value=0)
             }
+
+    The outbound values will be Python dictionaries by default, but you can have them
+    converted to other types by specifying an `out_type` function or class.
     """
 
+    # Transforms values to different type (this is an extension of GraphQL.js).
+    out_type: GraphQLInputFieldOutType
     ast_node: Optional[InputObjectTypeDefinitionNode]
     extension_ast_nodes: Optional[Tuple[InputObjectTypeExtensionNode]]
 
@@ -1123,6 +1129,7 @@ def __init__(
         name: str,
         fields: Thunk[GraphQLInputFieldMap],
         description: str = None,
+        out_type: GraphQLInputFieldOutType = None,
         ast_node: InputObjectTypeDefinitionNode = None,
         extension_ast_nodes: Sequence[InputObjectTypeExtensionNode] = None,
     ) -> None:
@@ -1132,6 +1139,8 @@ def __init__(
             ast_node=ast_node,
             extension_ast_nodes=extension_ast_nodes,
         )
+        if out_type is not None and not callable(out_type):
+            raise TypeError(f"The out type for {name} must be a function or a class.")
         if ast_node and not isinstance(ast_node, InputObjectTypeDefinitionNode):
             raise TypeError(
                 f"{name} AST node must be an InputObjectTypeDefinitionNode."
@@ -1144,6 +1153,7 @@ def __init__(
                 f"{name} extension AST nodes must be InputObjectTypeExtensionNode."
             )
         self._fields = fields
+        self.out_type = out_type or identity_func  # type: ignore
 
     def to_kwargs(self) -> Dict[str, Any]:
         return dict(**super().to_kwargs(), fields=self.fields.copy())

graphql/utilities/coerce_value.py

@@ -172,7 +172,11 @@ def coerce_value(
                     ),
                 )
 
-        return of_errors(errors) if errors else of_value(coerced_value_dict)
+        return (
+            of_errors(errors)
+            if errors
+            else of_value(type_.out_type(coerced_value_dict))  # type: ignore
+        )
 
     # Not reachable. All possible input types have been considered.
     raise TypeError(f"Unexpected input type: '{inspect(type_)}'.")  # pragma: no cover

graphql/utilities/value_from_ast.py

@@ -122,7 +122,8 @@ def value_from_ast(
             if is_invalid(field_value):
                 return INVALID
             coerced_obj[field_name] = field_value
-        return coerced_obj
+
+        return type_.out_type(coerced_obj)  # type: ignore
 
     if is_enum_type(type_):
         if not isinstance(value_node, EnumValueNode):

tests/execution/test_variables.py

@@ -8,6 +8,7 @@
     GraphQLEnumType,
     GraphQLEnumValue,
     GraphQLField,
+    GraphQLFloat,
     GraphQLInputField,
     GraphQLInputObjectType,
     GraphQLList,
@@ -40,6 +41,12 @@
     },
 )
 
+TestCustomInputObject = GraphQLInputObjectType(
+    "TestCustomInputObject",
+    {"x": GraphQLInputField(GraphQLFloat), "y": GraphQLInputField(GraphQLFloat)},
+    out_type=lambda value: f"(x|y) = ({value['x']}|{value['y']})",
+)
+
 
 TestNestedInputObject = GraphQLInputObjectType(
     "TestNestedInputObject",
@@ -81,6 +88,9 @@ def field_with_input_arg(input_arg: GraphQLArgument):
             GraphQLArgument(GraphQLNonNull(TestEnum))
         ),
         "fieldWithObjectInput": field_with_input_arg(GraphQLArgument(TestInputObject)),
+        "fieldWithCustomObjectInput": field_with_input_arg(
+            GraphQLArgument(TestCustomInputObject)
+        ),
         "fieldWithNullableStringInput": field_with_input_arg(
             GraphQLArgument(GraphQLString)
         ),
@@ -135,6 +145,22 @@ def executes_with_complex_input():
                     None,
                 )
 
+            def executes_with_custom_input():
+                # This is an extension of GraphQL.js.
+                result = execute_query(
+                    """
+                    {
+                      fieldWithCustomObjectInput(
+                        input: {x: -3.0, y: 4.5})
+                    }
+                    """
+                )
+
+                assert result == (
+                    {"fieldWithCustomObjectInput": "'(x|y) = (-3.0|4.5)'"},
+                    None,
+                )
+
             def properly_parses_single_value_to_list():
                 result = execute_query(
                     """

tests/type/test_definition.py

@@ -471,6 +471,18 @@ def accepts_an_input_object_type_with_a_field_function():
             assert isinstance(input_field, GraphQLInputField)
             assert input_field.type is ScalarType
 
+        def accepts_an_input_object_type_with_an_out_type_function():
+            # This is an extension of GraphQL.js.
+            input_obj_type = GraphQLInputObjectType(
+                "SomeInputObject", {}, out_type=dict
+            )
+            assert input_obj_type.out_type is dict
+
+        def provides_default_out_type_if_omitted():
+            # This is an extension of GraphQL.js.
+            input_obj_type = GraphQLInputObjectType("SomeInputObject", {})
+            assert input_obj_type.out_type is identity_func
+
         def rejects_an_input_object_type_with_incorrect_fields():
             input_obj_type = GraphQLInputObjectType("SomeInputObject", [])
             with raises(TypeError) as exc_info:
@@ -493,6 +505,17 @@ def rejects_an_input_object_type_with_incorrect_fields_function():
                 " or a function which returns such an object."
             )
 
+        def rejects_an_input_object_type_with_incorrect_out_type_function():
+            with raises(TypeError) as exc_info:
+                # noinspection PyTypeChecker
+                GraphQLInputObjectType(
+                    "SomeInputObject", {}, out_type=[]
+                )  # type: ignore
+            msg = str(exc_info.value)
+            assert msg == (
+                "The out type for SomeInputObject must be a function or a class."
+            )
+
     def describe_type_system_input_objects_fields_must_not_have_resolvers():
         def rejects_an_input_object_type_with_resolvers():
             with raises(

tests/utilities/test_coerce_value.py

@@ -241,6 +241,19 @@ def returns_error_for_a_misspelled_field():
                 " Did you mean bar?"
             ]
 
+        def transforms_values_with_out_type():
+            # This is an extension of GraphQL.js.
+            ComplexInputObject = GraphQLInputObjectType(
+                "Complex",
+                {
+                    "real": GraphQLInputField(GraphQLFloat),
+                    "imag": GraphQLInputField(GraphQLFloat),
+                },
+                out_type=lambda value: complex(value["real"], value["imag"]),
+            )
+            result = coerce_value({"real": 1, "imag": 2}, ComplexInputObject)
+            assert expect_value(result) == 1 + 2j
+
     def describe_for_graphql_list():
         TestList = GraphQLList(GraphQLInt)
 

tests/utilities/test_value_from_ast.py

@@ -174,3 +174,15 @@ def omits_input_object_fields_for_unprovided_variables():
             "{ requiredBool: $foo }",
             {"int": 42, "requiredBool": True},
         )
+
+    def transforms_values_with_out_type():
+        # This is an extension of GraphQL.js.
+        complex_input_obj = GraphQLInputObjectType(
+            "Complex",
+            {
+                "real": GraphQLInputField(GraphQLFloat),
+                "imag": GraphQLInputField(GraphQLFloat),
+            },
+            out_type=lambda value: complex(value["real"], value["imag"]),
+        )
+        _test_case(complex_input_obj, "{ real: 1, imag: 2 }", 1 + 2j)