How to use Batch API to do heavy processing in Drupal 8 & 9

How to use Batch API to do heavy processing in Drupal 8 & 9

The batch API in Drupal allows heavy and / or long processing to be carried out, without the risk of having an execution time exceeded on the part of its server.

in this article i want to do an example how to use the batch api.

So I have a route defined which calls the static "batchExample" method of my controller.

Function of who prepares the batch to be processed:

public function batchExample() {
    
 $batch = array(
            'title' => t('Import Data...'),
            'operations' => [],
            'init_message' => t('Commencing'),
            'progress_message' => t('Processed @current out of @total.'),
            'error_message' => t('An error occurred during processing'),
            'finished' => 'import_data_finished',
        );
        for ($i = 0; $i < 100; $i++) {
            $batch['operations'][] = ['import_data_test', [$i]];
        }

        batch_set($batch);

        // Only needed if not inside a form _submit handler.
        // Setting redirect in batch_process.
       return batch_process('/admin/content');

  }

here is an example if you want to use batch api inside form submit handler:

public function batchExample() { 
 $batch = array(
            'title' => t('Import Data...'),
            'operations' => [],
            'init_message' => t('Commencing'),
            'progress_message' => t('Processed @current out of @total.'),
            'error_message' => t('An error occurred during processing'),
            'finished' => 'import_data_finished',
        );
        for ($i = 0; $i < 100; $i++) {
            $batch['operations'][] = ['import_data_test', [$i]];
        }
        batch_set($batch);
  }

Here is the method called at the operations:

function import_data_test($nbre = 0, &$context)
{
    $context['message'] = 'Import Data N° ' . $nbre;
    $context['results'][] = $nbre;
    usleep(50000);
}

Here is the method called at the end of the batch:

function import_data_finished($success, $results, $operations)
{
    if ($success) {
        $message = \Drupal::translation()->formatPlural(
            count($results),
            'One item processed.', '@count items processed.'
        );
    } else {
        $message = t('Finished with an error.');
    }
    \Drupal::messenger()->addStatus($message);
}

screenshot for our example:

Nothing too complicated then, just add the import_data_test() and import_data_finished() methods in MODULENAME.module.