Export directive to support batch processing.

graphql/execution/base.py

@@ -103,11 +103,12 @@ class ExecutionResult(object):
     query, `errors` is null if no errors occurred, and is a
     non-empty array if an error occurred."""
 
-    __slots__ = 'data', 'errors', 'invalid'
+    __slots__ = 'data', 'errors', 'invalid', 'variable_values'
 
-    def __init__(self, data=None, errors=None, invalid=False):
+    def __init__(self, data=None, errors=None, invalid=False, variable_values=None):
         self.data = data
         self.errors = errors
+        self.variable_values = variable_values
 
         if invalid:
             assert data is None

graphql/execution/executor.py

@@ -6,6 +6,7 @@
 from six import string_types
 from promise import Promise, promise_for_dict, is_thenable
 
+from ..type.directives import GraphQLExportDirective
 from ..error import GraphQLError, GraphQLLocatedError
 from ..pyutils.default_ordered_dict import DefaultOrderedDict
 from ..pyutils.ordereddict import OrderedDict
@@ -72,7 +73,7 @@ def on_rejected(error):
 
     def on_resolve(data):
         if not context.errors:
-            return ExecutionResult(data=data)
+            return ExecutionResult(data=data, variable_values=context.variable_values)
         return ExecutionResult(data=data, errors=context.errors)
 
     promise = Promise(executor).catch(on_rejected).then(on_resolve)
@@ -133,6 +134,13 @@ def execute_fields(exe_context, parent_type, source_value, fields):
 
     for response_name, field_asts in fields.items():
         result = resolve_field(exe_context, parent_type, source_value, field_asts)
+        directives = field_asts[0].directives
+        if directives:
+            for directive in directives:
+                if directive.name.value == GraphQLExportDirective.name:
+                    variable_name = directive.arguments[0].value.value
+                    exe_context.variable_values.setdefault(variable_name, []).append(result)
+
         if result is Undefined:
             continue
 

graphql/execution/tests/test_directives.py

@@ -35,6 +35,13 @@ def test_if_true_includes_scalar():
     assert result.data == {'a': 'a', 'b': 'b'}
 
 
+def test_export():
+    result = execute_test_query('{ a, b @export(as: "ids") }')
+    assert not result.errors
+    assert result.data == {'a': 'a', 'b': 'b'}
+    assert result.variable_values == {'ids': ['b']}
+
+
 def test_if_false_omits_on_scalar():
     result = execute_test_query('{ a, b @include(if: false) }')
     assert not result.errors

graphql/execution/tests/test_nonnull.py

@@ -117,7 +117,6 @@ def test_nulls_a_nullable_field_that_throws_sync():
             sync
         }
     '''
-
     check(doc, ThrowingData(), {
         'data': {'sync': None},
         'errors': [{'locations': [{'column': 13, 'line': 3}], 'message': str(sync_error)}]

graphql/type/directives.py

@@ -103,6 +103,21 @@ def __init__(self, name, description=None, args=None, locations=None):
     ]
 )
 
+"""Used to export variable values as the result of a query (for batching)."""
+GraphQLExportDirective = GraphQLDirective(
+    name='export',
+    description='Exports variable values from the results of the query.',
+    args={
+        'as': GraphQLArgument(
+            type=GraphQLNonNull(GraphQLString),
+            description='Variable name used for export.',
+        ),
+    },
+    locations=[
+        DirectiveLocation.FIELD
+    ]
+)
+
 """Constant string used for default reason for a deprecation."""
 DEFAULT_DEPRECATION_REASON = 'No longer supported'