GraphQL\Type\Definition\Type::isOutputType PHP Метод

    public static function isOutputType($type)
    {
        $nakedType = self::getNamedType($type);
        return $nakedType instanceof OutputType;
    }

 public static function noInputTypesAsOutputFieldsRule()
 {
     return function ($context) {
         $operationMayNotBeInputType = function (Type $type, $operation) {
             if (!Type::isOutputType($type)) {
                 return new Error("Schema {$operation} must be Object Type but got: {$type}.");
             }
             return null;
         };
         /** @var Schema $schema */
         $schema = $context['schema'];
         $typeMap = $schema->getTypeMap();
         $errors = [];
         $queryType = $schema->getQueryType();
         if ($queryType) {
             $queryError = $operationMayNotBeInputType($queryType, 'query');
             if ($queryError !== null) {
                 $errors[] = $queryError;
             }
         }
         $mutationType = $schema->getMutationType();
         if ($mutationType) {
             $mutationError = $operationMayNotBeInputType($mutationType, 'mutation');
             if ($mutationError !== null) {
                 $errors[] = $mutationError;
             }
         }
         $subscriptionType = $schema->getSubscriptionType();
         if ($subscriptionType) {
             $subscriptionError = $operationMayNotBeInputType($subscriptionType, 'subscription');
             if ($subscriptionError !== null) {
                 $errors[] = $subscriptionError;
             }
         }
         foreach ($typeMap as $typeName => $type) {
             if ($type instanceof ObjectType || $type instanceof InterfaceType) {
                 $fields = $type->getFields();
                 foreach ($fields as $fieldName => $field) {
                     if ($field->getType() instanceof InputObjectType) {
                         $errors[] = new Error("Field {$typeName}.{$field->name} is of type " . "{$field->getType()->name}, which is an input type, but field types " . "must be output types!");
                     }
                 }
             }
         }
         return !empty($errors) ? $errors : null;
     };
 }