index.md

Errors handling

By default in no debug mode all errors will be logged and replace by a generic error message. Only query parsed error won't be replaced. If you want to send explicit error or warnings messages to your users you can use exceptions:

1- Overblog\GraphQLBundle\Error\UserError to send unique error

use Overblog\GraphQLBundle\Error\UserError;

class CharacterResolver
{
    //...
    public function resolveHuman($args)
    {
        $humans = StarWarsData::humans();

        if (!isset($humans[$args['id']])) {
            throw new UserError(sprintf('Could not find Human#%d', $args['id']));
        }

        return $humans[$args['id']];
    }
    //...
}

2- Overblog\GraphQLBundle\Error\UserErrors to send multiple errors

use Overblog\GraphQLBundle\Error\UserError;
use Overblog\GraphQLBundle\Error\UserErrors;

class CharacterResolver
{
    //...
    public function resolveHumanAndDroid($args)
    {
        $humans = StarWarsData::humans();
        
        $errors = [];

        if (!isset($humans[$args['human_id']])) {
            $errors[] = new UserError(sprintf('Could not find Human#%d', $args['human_id']));
        }

        $droids = StarWarsData::droids();

        if (!isset($droids[$args['droid_id']])) {
            $errors[] = sprintf('Could not find Droid#%d', $args['droid_id']);
        }

        if (!empty($errors)) {
            throw new UserErrors($errors);
        }

        return [
            'human' => $humans[$args['human_id']],
            'droid' => $droids[$args['droid_id']],
        ];
    }
    //...
}

3- Overblog\GraphQLBundle\Error\UserWarning to send unique warning

use Overblog\GraphQLBundle\Error\UserWarning;

class CharacterResolver
{
    //...
    public function resolveHuman($args)
    {
        $humans = StarWarsData::humans();

        if (!isset($humans[$args['id']])) {
            throw new UserWarning(sprintf('Could not find Human#%d', $args['id']));
        }

        return $humans[$args['id']];
    }
    //...
}

Warnings can be found in the response under extensions.warnings map.

If you want to map your own exceptions to warnings and errors you can define a custom exception mapping:

overblog_graphql:
    #... 
    errors_handler:
        #...
        # change to true to try to map an exception to a parent exception if the exact exception is not in 
        # the mapping
        map_exceptions_to_parent: false
        exceptions:
            warnings:
                - "Symfony\\Component\\Routing\\Exception\\ResourceNotFoundException"
            errors:
                - "InvalidArgumentException"

The mapping is handled inside the Overblog\GraphQLBundle\Error\ErrorHandler class using an instance of the Overblog\GraphQLBundle\Error\ExceptionConverter class. Since this class implements an interface and is registered as a service in the dependency container, you can easily swap it and customize the logic.

namespace App\Error;

use Overblog\GraphQLBundle\Error\ExceptionConverterInterface;
use Overblog\GraphQLBundle\Error\UserError;

final class ExceptionConverter implements ExceptionConverterInterface
{
    public function convertException(\Throwable $exception): \Throwable
    {
        return new UserError($exception->getMessage(), $exception->getCode(), $exception->getPrevious());
    }
}

App\Error\ExceptionConverter: ~

Overblog\GraphQLBundle\Error\ExceptionConverterInterface:
    alias: '@App\Error\ExceptionConverter'

You can custom the default errors handler using configuration:

overblog_graphql:
    errors_handler:
        enabled: true # false will totally disabled errors handling
        internal_error_message: ~ # custom generic error message
        rethrow_internal_exceptions: false # re-throw internal exception
        debug: false # will add trace stack and debugMessage to error
        log: true # false will disabled the default logging behavior
        logger_service: logger # the service to use to log

The message of those exceptions are then shown to the user like other UserErrors or UserWarnings.

Custom error Formatting

see error formatting Event

Custom error handling / formatting

This can also be done by using events.

• First totally disabled default errors handler:

  overblog_graphql:
      errors_handler: false

• Listen to executor result event

  App\EventListener\MyErrorHandler:
      tags:
          - { name: kernel.event_listener, event: graphql.post_executor, method: onPostExecutor }

  <?php
  
  namespace App\EventListener;
  
  use GraphQL\Error\Error;
  use GraphQL\Error\FormattedError;
  use Overblog\GraphQLBundle\Event\ExecutorResultEvent;
  
  class MyErrorHandler
  {
    public function onPostExecutor(ExecutorResultEvent $event)
    {
        $myErrorFormatter = function(Error $error) {
            return FormattedError::createFromException($error);
        };
  
        $myErrorHandler = function(array $errors, callable $formatter) {
            return array_map($formatter, $errors);
        };
  
        $event->getResult()
            ->setErrorFormatter($myErrorFormatter)
            ->setErrorsHandler($myErrorHandler);
    }
  }