Drupal At Your Fingertips

Last synced: 2025-10-31
Upstream: https://github.com/selwynpolit/d9book
Topics synced: 53


# about

**Source**: [Drupal at Your Fingertips - about](https://drupalatyourfingertips.com/about)
**Author**: Selwyn Polit

---

## Full Documentation

**View online**: https://drupalatyourfingertips.com/about

This chapter covers:
- Detailed explanations with code examples
- Best practices and common patterns
- Step-by-step implementation guides
- Troubleshooting and debugging tips

---

---

**Last verified**: 2025-10-31


# actions

**Source**: [Drupal at Your Fingertips - actions](https://drupalatyourfingertips.com/actions)
**Author**: Selwyn Polit

---

## Full Documentation

**View online**: https://drupalatyourfingertips.com/actions

This chapter covers:
- Detailed explanations with code examples
- Best practices and common patterns
- Step-by-step implementation guides
- Troubleshooting and debugging tips

---

---

**Last verified**: 2025-10-31


# ai

**Source**: [Drupal at Your Fingertips - ai](https://drupalatyourfingertips.com/ai)
**Author**: Selwyn Polit

---

## Full Documentation

**View online**: https://drupalatyourfingertips.com/ai

This chapter covers:
- Detailed explanations with code examples
- Best practices and common patterns
- Step-by-step implementation guides
- Troubleshooting and debugging tips

---

---

**Last verified**: 2025-10-31


# AJAX

**Source**: [Drupal at Your Fingertips - ajax](https://drupalatyourfingertips.com/ajax)
**Author**: Selwyn Polit

Quick reference for AJAX in Drupal with practical code examples.

---

## Core Concept

AJAX in Drupal enables partial page updates without full page refreshes. Use the `#ajax` property on form elements to trigger callbacks that return AJAX commands (replace, append, remove, etc.) to manipulate the page.

## AJAX in Forms

**Basic pattern**:
```php
$form['category'] = [
  '#type' => 'select',
  '#title' => $this->t('Category'),
  '#options' => ['tech' => 'Tech', 'news' => 'News'],
  '#ajax' => [
    'callback' => '::updateItems',  // Method name
    'wrapper' => 'items-wrapper',   // HTML ID to replace
    'event' => 'change',            // Trigger event (default: change)
  ],
];

$form['items'] = [
  '#type' => 'select',
  '#title' => $this->t('Items'),
  '#prefix' => '<div id="items-wrapper">',
  '#suffix' => '</div>',
];
```

**AJAX callback**:
```php
public function updateItems(array &$form, FormStateInterface $form_state) {
  // Return the element to replace
  return $form['items'];
}
```

---

## AJAX Properties

**Common #ajax properties**:
| Property | Purpose | Default |
|----------|---------|---------|
| `callback` | Method to call | Required |
| `wrapper` | HTML ID to replace | Required |
| `event` | JavaScript event | 'change' |
| `method` | HTTP method | 'POST' |
| `progress` | Progress indicator | `['type' => 'throbber']` |
| `effect` | jQuery effect | 'fade' |
| `speed` | Effect speed | 'slow' |

**Progress indicators**:
```php
'#ajax' => [
  'callback' => '::myCallback',
  'wrapper' => 'my-wrapper',

  // Throbber (default)
  'progress' => ['type' => 'throbber'],

  // Full page progress bar
  'progress' => ['type' => 'fullscreen'],

  // Custom message
  'progress' => [
    'type' => 'throbber',
    'message' => $this->t('Loading...'),
  ],

  // No progress indicator
  'progress' => ['type' => 'none'],
],
```

---

## AJAX Responses

**Return render array** (most common):
```php
public function callback(array &$form, FormStateInterface $form_state) {
  // Return element to replace
  return $form['subcategory'];
}
```

**Return AjaxResponse with commands**:
```php
use Drupal\Core\Ajax\AjaxResponse;
use Drupal\Core\Ajax\ReplaceCommand;
use Drupal\Core\Ajax\AppendCommand;

public function callback(array &$form, FormStateInterface $form_state) {
  $response = new AjaxResponse();

  // Replace element
  $response->addCommand(new ReplaceCommand('#items-wrapper', $form['items']));

  // Append content
  $response->addCommand(new AppendCommand('#