visitOperationDefinitionNode method

@override OperationDefinitionNode visitOperationDefinitionNode(OperationDefinitionNode node)

Visit OperationDefinitionNode.

Implementation

@override
OperationDefinitionNode visitOperationDefinitionNode(
  OperationDefinitionNode node,
) {
  // Subscriptions can only have a single root type
  // https://spec.graphql.org/June2018/#example-2353b
  if (node.type == OperationType.subscription) {
    return node;
  }

  final hasTypename = node.selectionSet.selections
      .whereType<FieldNode>()
      .any((node) => node.name.value == '__typename');

  if (hasTypename) return node;

  return OperationDefinitionNode(
    type: node.type,
    name: node.name,
    variableDefinitions: node.variableDefinitions,
    directives: node.directives,
    selectionSet: SelectionSetNode(
      selections: <SelectionNode>[
        FieldNode(
          name: NameNode(value: '__typename'),
        ),
        ...node.selectionSet.selections,
      ],
    ),
  );
}