[RFC] Type condition optional on inline fragments

Implements graphql/graphql-spec#100

Author: jhgg

graphql/core/execution/base.py

@@ -166,11 +166,17 @@ def should_include_node(ctx, directives):
 
 
 def does_fragment_condition_match(ctx, fragment, type_):
-    conditional_type = type_from_ast(ctx.schema, fragment.type_condition)
+    type_condition_ast = fragment.type_condition
+    if not type_condition_ast:
+        return True
+
+    conditional_type = type_from_ast(ctx.schema, type_condition_ast)
     if conditional_type == type_:
         return True
+
     if isinstance(conditional_type, (GraphQLInterfaceType, GraphQLUnionType)):
         return conditional_type.is_possible_type(type_)
+
     return False
 
 

graphql/core/language/parser.py

@@ -315,17 +315,22 @@ def parse_fragment(parser):
     # Corresponds to both FragmentSpread and InlineFragment in the spec
     start = parser.token.start
     expect(parser, TokenKind.SPREAD)
-    if parser.token.value == 'on':
-        advance(parser)
-        return ast.InlineFragment(
-            type_condition=parse_named_type(parser),
+    if peek(parser, TokenKind.NAME) and parser.token.value != 'on':
+        return ast.FragmentSpread(
+            name=parse_fragment_name(parser),
             directives=parse_directives(parser),
-            selection_set=parse_selection_set(parser),
             loc=loc(parser, start)
         )
-    return ast.FragmentSpread(
-        name=parse_name(parser),
+
+    type_condition = None
+    if parser.token.value == 'on':
+        advance(parser)
+        type_condition = parse_named_type(parser)
+
+    return ast.InlineFragment(
+        type_condition=type_condition,
         directives=parse_directives(parser),
+        selection_set=parse_selection_set(parser),
         loc=loc(parser, start)
     )
 

graphql/core/language/printer.py

@@ -50,9 +50,12 @@ def leave_FragmentSpread(self, node, *args):
         return '...' + node.name + wrap(' ', join(node.directives, ' '))
 
     def leave_InlineFragment(self, node, *args):
-        return ('... on ' + node.type_condition + ' ' +
-                wrap('', join(node.directives, ' '), ' ') +
-                node.selection_set)
+        return join([
+            '...',
+            wrap('on ', node.type_condition),
+            join(node.directives, ''),
+            node.selection_set
+        ], ' ')
 
     def leave_FragmentDefinition(self, node, *args):
         return ('fragment {} on {} '.format(node.name, node.type_condition) +

graphql/core/utils/type_info.py

@@ -73,7 +73,8 @@ def enter(self, node):
                 type = schema.get_mutation_type()
             self._type_stack.append(type)
         elif isinstance(node, (ast.InlineFragment, ast.FragmentDefinition)):
-            type = type_from_ast(schema, node.type_condition)
+            type_condition_ast = node.type_condition
+            type = type_from_ast(schema, type_condition_ast) if type_condition_ast else self.get_type()
             self._type_stack.append(type)
         elif isinstance(node, ast.VariableDefinition):
             self._input_type_stack.append(type_from_ast(schema, node.type))

tests/core_language/fixtures.py

@@ -18,6 +18,12 @@
         }
       }
     }
+    ... @skip(unless: $foo) {
+      id
+    }
+    ... {
+      id
+    }
   }
 }
 

tests/core_language/test_printer.py

@@ -40,6 +40,12 @@ def test_prints_kitchen_sink():
         }
       }
     }
+    ... @skip(unless: $foo) {
+      id
+    }
+    ... {
+      id
+    }
   }
 }