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Ajax Form

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Drupal Dictionary

This glossary describes terminology and acronyms used in the Drupal project and by the Drupal community.

This is a Drupal 9 version of the glossary, however, these terms are not (typically) specific to any version of Drupal.

We will add new terms and other terms which are from the web development industry.

If you feel that there is a term missing, please add it as a comment.

Full list of available #ajax properties

Adding AJAX callback events to form fields allows to dynamically update fields and other markup, while users interact with the forms.

More general information about Drupal and Ajax can be found at Drupal Ajax API Guide and Drupal's Ajax API documentation (at api.drupal.org).

Some working examples can be found in the Examples for Developers modules, specifically in the AJAX Example submodule, see its Form folder.

Select Element, its more hard to deal with Ajax

Drupal Form Select element is harder to deal with when desired to add to it Ajax activities

Ajax is a bit misleading, it's not all on the client side, and if we still want to handle it from the code which is located on the server, e/s program it with the form objects like $form & $form_state it still needs to update the server side within the flow, and the form is still need to have synchronization transactions between the client, server, and cache

not enough documentation on that, especially when working with specific elements like SELECT

Code Snippet

    public function buildForm(array $form, FormStateInterface $form_state, $dashboard = 0, $project=0, $sprint=0, $redirect='') {  //
      $config = \Drupal::config('drupalvip_task.settings');
      $log = $config->get('log');
      ($log)? \Drupal::logger("drupalvip_task")->debug(__FUNCTION__ . ": START "):'';      
      ($log)? \Drupal::logger("drupalvip_task")->debug("Form Args: da[$dashboard] pr[$project] sp[$sprint] rd[$redirect]"):'';
      
      $form['redirect'] = array(
          '#type' => 'value',
          '#value' => $redirect,
      );
      
      //dashboard select
      $dashboard_default = ($dashboard==0) ? null : $dashboard;
      $dashboard_options = DashboardController::getDashboards();
      $form['dashboard_select'] = [
        '#type' => 'select',
        '#title' => t('Dashboard'),
        //'#name' => 'dashboard-select',  <-- prevent the form_state to update
        '#options' => $dashboard_options,
        '#sort_options' => TRUE,
        '#required' => TRUE,
        '#empty_option' => "-- SELECT --",
        '#size' => 1,
        '#default_value' => $dashboard_default,
        '#attributes' => [
          'class' => ['use-ajax'],
          //'id' => "edit-dashboard-select", <-- this prevent the callback
        ],         
        '#ajax' => [
          'callback' => '::submitFormDashboardSelected',
          'wrapper' => 'group-select-wrapper',
          'suppress_required_fields_validation' => TRUE,
        ],        
      ];      
      
      $form['group'] = [
        '#type' => 'fieldgroup',
        '#prefix' => '<div id="group-select-wrapper">',
        '#suffix' => '</div>',         
      ];      
        $options[0] = "-- select --";        
        $form['group']['project_select'] = [
          '#type' => 'select',
          '#title' => $this->t('Project'),
          '#options' => $options,
          '#limit_validation_errors' => [],
          //'#empty_option' => "-- select --",
          '#size' => 1,        
          '#default_value' => 0, 
        ]; 
        if ($dashboard > 0) {
          $project_options = DashboardController::getProjects($dashboard);
          $project_options_2 = $options + $project_options ;
          $form['group']['project_select']['#options'] = $project_options_2; //$project_options; 
          $form['group']['project_select']['#default_value'] = $project;
        }      

        $form['group']['sprint_select'] = [
          '#type' => 'select',
          '#title' => $this->t('Sprint'),
          '#options' => $options,
          '#limit_validation_errors' => [],
          //'#empty_option' => "-- select --",
          '#size' => 1,        
          '#default_value' => 0, 
        ]; 
        if ($dashboard > 0) {
          $sprint_options = DashboardController::getSprints($dashboard);
          $sprint_options_2 = $options + $sprint_options ;
          $form['group']['sprint_select']['#options'] = $sprint_options_2; 
          $form['group']['sprint_select']['#default_value'] = $sprint;
        }      
        
      $form['subject'] =  [
        '#type' => 'textfield',
        '#title' => $this->t('Subject'),
        '#required' => TRUE,
        '#attributes' => [
          //'id' => "task-subject-box",
        ],        
      ];
      
      $form['actions'] = [
        '#type' => 'actions',
        '#attributes' => [
          'class' => ['form_actions'],
        ],         
      ];
        $form['actions']['cancel'] = [
          '#type' => 'submit',
          '#value' => $this->t('Cancel'),
          '#attributes' => [
            'class' => ['button','use-ajax','form-submit-modal','action-cancel' ],
          ],
          '#ajax' => [
            'callback' => [$this, 'submitFormClose'],
            'event' => 'click',
          ],
        ];       
        $form['actions']['create'] = [
          '#type' => 'submit',
          '#value' => $this->t('Create'),
          '#attributes' => [
            'class' => ['button','use-ajax','form-submit-modal','action-create' ],
          ],
          '#ajax' => [
            'callback' => [$this, 'submitFormCreate'],
            'event' => 'click',
            'onclick' => 'javascript:var s=this;setTimeout(function(){s.value="Saving...";s.disabled=true;},1);',
          ],
        ];              

      $form['#attributes']['class'][] = 'drupalvip_form';  
      $form['#attached']['library'][] = 'drupalvip_task/content';
      $form['#attached']['library'][] = 'core/drupal.dialog.ajax';
      $form['#attached']['library'][] = 'core/drupal.ajax';
      $form['#attached']['library'][] = 'core/jquery.form';
      
      ($log)? \Drupal::logger("drupalvip_task")->debug(__FUNCTION__ . ": RETURN FORM "):'';
      return $form;    
    }

Select Element with AJAX updating form dynamically

Using AJAX callbacks to dynamically react on user input, alter form elements, show dialog boxes or run custom Javascript functions.

Ajax is the process of dynamically updating parts of a page's HTML based on data from the server without requiring full page refresh. You can find events triggering Ajax requests all over Drupal.

Code Snippet

<?php
  namespace Drupal\drupalvip\Form;

  use Drupal\Core\Form\FormBase;
  use Drupal\Core\Form\FormStateInterface;
  
  class AjaxForm extends FormBase {    

    public function getFormId() {
      return 'mymodule_ajax_form';
    }

    public function buildForm(array $form, FormStateInterface $form_state) {
      $triggering_element = $form_state->getTriggeringElement();

      $form['country'] = [
        '#type' => 'select',
        '#title' => $this->t('Country'),
        '#options' => [
          'serbia' => $this->t('Serbia'),
          'usa' => $this->t('USA'),
          'italy' => $this->t('Italy'),
          'france' => $this->t('France'),
          'germany' => $this->t('Germany'),
        ],
        '#ajax' => [
          'callback' => [$this, 'reloadCity'],
          'event' => 'change',
          'wrapper' => 'city-field-wrapper',
        ],
      ];

      $form['city'] = [
        '#type' => 'select',
        '#title' => $this->t('City'),
        '#options' => [
          'belgrade' => $this->t('Belgrade'),
          'washington' => $this->t('Washington'),
          'rome' => $this->t('Rome'),
          'paris' => $this->t('Paris'),
          'berlin' => $this->t('Berlin'),
        ],
        '#prefix' => '<div id="city-field-wrapper">',
        '#suffix' => '</div>',
        '#value' => empty($triggering_element) ? 'belgrade' : $this->getCityForCountry($triggering_element['#value']),
      ];

      return $form;
    }

    public function reloadCity(array $form, FormStateInterface $form_state) {
      return $form['city'];
    }

    protected function getCityForCountry($country) {
      $map = [
        'serbia' => 'belgrade',
        'usa' => 'washington',
        'italy' => 'rome',
        'france' => 'paris',
        'germany' => 'berlin',
      ];
      return $map[$country] ?? NULL;
    }

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

} // end of class

Drupal has adopted Ajax, review how it implemented in Forms

Drupal has adopted Ajax - full integration

Ajax is the process of dynamically updating parts of a page's HTML based on data from the server.
When a specified event takes place, a PHP callback is triggered, which performs server-side logic and may return updated markup or JavaScript commands to run.
After the return, the browser runs the JavaScript or updates the markup on the fly, with no full page refresh necessary.

Many different events can trigger Ajax responses, including Clicking a button, Pressing a key, Moving the mouse

Code Snippet

$response = new AjaxResponse(); 
$response->addCommand(new ReplaceCommand('#edit-date-format-suffix', '<small id="edit-date-format-suffix">' . $format . '</small>')); 
return $response;

'#ajax' => [
  'callback' => 'Drupal\config_translation\FormElement\DateFormat::ajaxSample',
  'event' => 'keyup',  
  'progress' => [ 'type' => 'throbber', 'message' => NULL,  ], 
],