Support directives on variable definitions

This adds language support for directives on variable definitions
following graphql/graphql-spec#510.

This is **only** language support so servers don't choke when
receiving queries using this feature.

Author: anthonymedinawork

CHANGES.md

@@ -19,6 +19,8 @@ Unreleased
 - Added `ResolveInfo.get_directive_arguments`
 - Added `ResolveInfo.selected_fields` and `utilities.selected_fields`.
 
+- Support directives on variable definitions: this adds language support for directives on variable definitions following [graphql/graphql-spec#510](https://github.com/graphql/graphql-spec/pull/510). This is **only** language support so servers don't choke when receiving queries using this feature.
+
 ### Fixed
 
 - Introducing `pyproject.toml` broke Cython integration through build isolation. This is now fixed by always requiring cython as a a build dependency (through `build-system.requires`) and only enabling support behind the `PY_GQL_USE_CYTHON` env variable.

py_gql/lang/ast.py

@@ -232,20 +232,29 @@ def __init__(
         self.loc = loc
 
 
-class VariableDefinition(Node):
-    __slots__ = ("source", "loc", "variable", "type", "default_value")
+class VariableDefinition(SupportDirectives, Node):
+    __slots__ = (
+        "source",
+        "loc",
+        "variable",
+        "type",
+        "default_value",
+        "directives",
+    )
 
     def __init__(
         self,
         variable: Variable,
         type: Type,
         default_value=None,  # type: Optional[Value]
+        directives=None,  # type: Optional[List[Directive]]
         source: Optional[str] = None,
         loc: Optional[Tuple[int, int]] = None,
     ):
         self.variable = variable
         self.type = type
         self.default_value = default_value
+        self.directives = directives or []  # type: List[Directive]
         self.source = source
         self.loc = loc
 

py_gql/lang/parser.py

@@ -52,6 +52,7 @@
         "FRAGMENT_DEFINITION",
         "FRAGMENT_SPREAD",
         "INLINE_FRAGMENT",
+        "VARIABLE_DEFINITION",
         # Type System Definitions
         "SCHEMA",
         "SCALAR",
@@ -553,7 +554,7 @@ def parse_variable_definitions(self) -> List[_ast.VariableDefinition]:
 
     def parse_variable_definition(self) -> _ast.VariableDefinition:
         """
-        VariableDefinition : Variable : Type DefaultValue?
+        VariableDefinition : Variable : Type DefaultValue? Directives[Const]?
         """
         start = self.peek()
         return _ast.VariableDefinition(
@@ -566,6 +567,7 @@ def parse_variable_definition(self) -> _ast.VariableDefinition:
                 if self.skip(Equals)
                 else None
             ),
+            directives=self.parse_directives(True),
             loc=self._loc(start),
             source=self._source,
         )

py_gql/lang/printer.py

@@ -132,10 +132,17 @@ def print_operation_definition(self, node: _ast.OperationDefinition) -> str:
         )
 
     def print_variable_definition(self, node: _ast.VariableDefinition) -> str:
-        return "%s: %s%s" % (
-            self.print_variable(node.variable),
-            self(node.type),
-            _wrap(" = ", self(node.default_value)),
+        return _join(
+            [
+                "%s: %s%s"
+                % (
+                    self.print_variable(node.variable),
+                    self(node.type),
+                    _wrap(" = ", self(node.default_value)),
+                ),
+                self.print_directives(node),
+            ],
+            " ",
         )
 
     def print_variable_definitions(

tests/test_lang/test_ast_printer.py

@@ -403,3 +403,30 @@ def test_custom_indentation_object():
             """
         )
     )
+
+
+def test_variable_definitions():
+    assert (
+        print_ast(
+            parse(
+                """
+                query Query(
+                    $a: ComplexType,
+                    $b: Boolean = false,
+                    $c: String @foo,
+                    $d: Int! = 42 @bar(value: 42)
+                ) {
+                    id
+                }
+                """,
+            )
+        )
+        == dedent(
+            """
+        query Query($a: ComplexType, $b: Boolean = false, $c: String @foo, \
+$d: Int! = 42 @bar(value: 42)) {
+          id
+        }
+        """
+        )
+    )

tests/test_lang/test_parser.py

@@ -467,3 +467,60 @@ def test_it_parses_inline_fragment_without_type():
             ],
         ),
     )
+
+
+def test_it_parses_variable_definition_with_directives():
+    assert_node_equal(
+        parse("query ($foo: Int @bar @baz) { foo }", no_location=True),
+        _ast.Document(
+            definitions=[
+                _ast.OperationDefinition(
+                    "query",
+                    _ast.SelectionSet(
+                        selections=[_ast.Field(name=_ast.Name(value="foo"),)],
+                    ),
+                    variable_definitions=[
+                        _ast.VariableDefinition(
+                            variable=_ast.Variable(
+                                name=_ast.Name(value="foo"),
+                            ),
+                            type=_ast.NamedType(name=_ast.Name(value="Int"),),
+                            directives=[
+                                _ast.Directive(name=_ast.Name(value="bar")),
+                                _ast.Directive(name=_ast.Name(value="baz")),
+                            ],
+                        )
+                    ],
+                )
+            ],
+        ),
+    )
+
+
+def test_it_parses_variable_definition_with_default_and_directives():
+    assert_node_equal(
+        parse("query ($foo: Int = 42 @bar @baz) { foo }", no_location=True),
+        _ast.Document(
+            definitions=[
+                _ast.OperationDefinition(
+                    "query",
+                    _ast.SelectionSet(
+                        selections=[_ast.Field(name=_ast.Name(value="foo"),)],
+                    ),
+                    variable_definitions=[
+                        _ast.VariableDefinition(
+                            variable=_ast.Variable(
+                                name=_ast.Name(value="foo"),
+                            ),
+                            type=_ast.NamedType(name=_ast.Name(value="Int"),),
+                            default_value=_ast.IntValue(value="42"),
+                            directives=[
+                                _ast.Directive(name=_ast.Name(value="bar")),
+                                _ast.Directive(name=_ast.Name(value="baz")),
+                            ],
+                        )
+                    ],
+                )
+            ],
+        ),
+    )