How to make a batch process in drupal 8 delete node

 curd_batch.batch_delete_form:

  path: '/batch_delete_form'

  defaults:

    _form: 'Drupal\curd_batch\Form\BatchDeleteForm'

    _title: 'Batch delete nodes form'

  requirements:

    _permission: 'access content'

//src/Form

<?php

namespace Drupal\curd_batch\Form;

 

use Drupal\Core\Form\FormBase;

use Drupal\Core\Form\FormStateInterface;

 

 

class BatchDeleteForm extends FormBase {

 

    public function buildForm(array $form, FormStateInterface $form_state) {

 

        $form['from_nid'] = [

            '#type' => 'textfield',

            '#title' => $this->t('From node ID'),

            '#required' => TRUE,

        ];

 

        $form['to_nid'] = [

            '#type' => 'textfield',

            '#title' => $this->t('To node ID'),

            '#required' => TRUE,

        ];

 

        // Add a submit button that handles the submission of the form.

        $form['actions']['submit'] = [

          '#type' => 'submit',

          '#value' => $this->t('Delete nodes in batches'),

        ];

 

        return $form;

    }

 

    public function submitForm(array &$form, FormStateInterface $form_state) {

 

        // Get all data to be processed.

        $from_nid = $form_state->getValue('from_nid');

        $to_nid = $form_state->getValue('to_nid');

 

        $all_nids = \Drupal::entityQuery('node')

                              ->condition('type', 'article')

                              ->condition('nid', $from_nid, '>=')

                              ->condition('nid', $to_nid, '<=')

                            ->execute();

// echo "<pre>";

//         print_r($all_nids);

//         die();

 

        // Breakdown your process into small batches(operations).

        // $all_nid = Array ( [1] => 1 [2] => 2 [3] => 3 )

        //      Delete 50 nodes per batch.

        $operations = [];

        foreach (array_chunk($all_nids, 50) as $smaller_batch_data) {

            $operations[] = ['\Drupal\curd_batch\Form\BatchDeleteForm::batchDelete'

                                            , [$smaller_batch_data]];

        }

 

        // Setup and define batch informations.

        $batch = array(

            'title' => t('Deleting nodes in batch...'),

            'operations' => $operations,

            'finished' => '\Drupal\curd_batch\Form\BatchDeleteForm::batchFinished',

        );

        batch_set($batch);

    }

 

    // Implement the operation method.

    public static function batchDelete($smaller_batch_data, &$context) {

        // Deleting nodes.

        $storage_handler = \Drupal::entityTypeManager()->getStorage('node');

        $entities = $storage_handler->loadMultiple($smaller_batch_data);

        $storage_handler->delete($entities);

 

        // Display data while running batch.

        $batch_size=sizeof($smaller_batch_data);

        $batch_number=sizeof($context['results'])+1;

        $context['message'] = sprintf("Deleting %s nodes per batch. Batch #%s"

                                            , $batch_size, $batch_number);

        $context['results'][] = sizeof($smaller_batch_data);

    }

 

    // What to do after batch completed. Display success or error message.

    public static function batchFinished($success, $results, $operations) {

        if ($success) {

            $message = count($results). ' batches processed.';

        }

        else{

            $message = 'Finished with an error.';

        }

        // drupal_set_message($message);

         \Drupal::messenger()->addMessage($message);

    }    

 

    public function getFormId() {

        return 'tradesteps_batch_delete_form';

    }

 

}