Controllers & AJAX

The October CMS backend implements an Model-View-Controller (MVC) pattern. Controllers manage backend pages and implement various features like forms and lists. This article describes how to develop backend controllers and how to configure controller behaviors.

Each controller is represented with a PHP script which resides in the the /controllers subdirectory of a Plugin directory. Controller views are .htm files that reside in the controller view directory. The controller view directory name matches the controller class name written in lowercase. The view directory can also contain controller configuration files. An example of a controller directory structure:

├── plugins
|   └── acme
|       └── blog
|           ├── controllers
|           |   ├── users                <== View Directory
|           |   |   ├── _partial.htm     <== Partial File
|           |   |   ├── config_form.yaml <== Config File
|           |   |   └── index.htm        <== View File
|           |   └── Users.php            <== Controller Class
|           └── Plugin.php

Tip: For a practical example of using backend controllers, check out the Beyond Behaviors tutorial series (opens new window).

# Class Definition

Controller classes must extend the \Backend\Classes\Controller class. As any other plugin class, controllers should belong to the plugin namespace. The most basic representation of a Controller used inside a Plugin looks like this.

namespace Acme\Blog\Controllers;

class Posts extends \Backend\Classes\Controller
{
    public function index()    // <=== Action method
    {

    }
}

Usually each controller implements functionality for working with a single type of data - like blog posts or categories. All backend behaviors described below assume this convention.

# Controller Properties

The backend controller base class defines a number of properties that allow to configure the page appearance and manage the page security:

# Actions, Views and Routing

Public controller methods, called actions are coupled to view files which represent the page corresponding the action. Back-end view files use PHP syntax. Example of the index.htm view file contents, corresponding to the index action method:

<h1>Hello World</h1>

URL of this page is made up of the author name, plugin name, controller name and action name.

backend/[author name]/[plugin name]/[controller name]/[action name]

The above Controller results in the following:

http://example.com/backend/acme/blog/users/index

# Passing Data to Views

Use the controller's $vars property to pass any data directly to your view:

$this->vars['myVariable'] = 'value';

The variables passed with the $vars property can now be accessed directly in your view:

<p>The variable value is <?= $myVariable ?></p>

# Setting the Navigation Context

Plugins can register the backend navigation menus and submenus in the plugin registration file. The navigation context determines what backend menu and submenu are active for the current backend page. You can set the navigation context with the BackendMenu class:

BackendMenu::setContext('Acme.Blog', 'blog', 'categories');

The first parameter specifies the author and plugin names. The second parameter sets the menu code. The optional third parameter specifies the submenu code. Usually you call the BackendMenu::setContext in the controller constructor.

namespace Acme\Blog\Controllers;

class Categories extends \Backend\Classes\Controller {

public function __construct()
{
    parent::__construct();

    BackendMenu::setContext('Acme.Blog', 'blog', 'categories');
}

You can set the title of the backend page with the $pageTitle property of the controller class (note that the form and list behaviors can do it for you):

$this->pageTitle = 'Blog categories';

# Using AJAX Handlers

The backend AJAX framework uses the same AJAX library as the front-end pages. The library is loaded automatically on the backend pages.

# Backend AJAX Handlers

The backend AJAX handlers can be defined in the controller class or widgets. In the controller class the AJAX handlers are defined as public methods with the name starting with "on" string: onCreateTemplate, onGetTemplateList, etc.

Back-end AJAX handlers can return an array of data, throw an exception or redirect to another page (see AJAX event handlers). You can use $this->vars to set variables and the controller's makePartial method to render a partial and return its contents as a part of the response data.

public function onOpenTemplate()
{
    if (Request::input('someVar') != 'someValue') {
        throw new ApplicationException('Invalid value');
    }

    $this->vars['foo'] = 'bar';

    return [
        'partialContents' => $this->makePartial('some-partial')
    ];
}

# Triggering AJAX Requests

The AJAX request can be triggered with the data attributes API or the JavaScript API. Please see the front-end AJAX library for details. The following example shows how to trigger a request with a backend button.

<button
    type="button"
    data-request="onDoSomething"
    class="btn btn-default">
    Do something
</button>

Note: You can specifically target the AJAX handler of a widget using a prefix widget::onName. See the widget AJAX handler article for more details.

# Overriding a Response

You can override responses in your backend controllers as a mechanism for making changes to the response of a HTTP request. For example, you may wish to specify a HTTP header for certain actions in your controller, or redirect users if they don't meet certain criteria.

Overriding a response is useful particularly when extending other controllers. However you may find it useful to call these methods locally.

\Author\Plugin\Controllers\SomeController::extend(function($controller) {
    $controller->setResponseHeader('Test-Header', 'Test');
});

If you want to check the routed action or parameters, you can find these available in the controller action and params properties.

Author\Plugin\Controllers\SomeController::extend(function($controller) {
    if ($this->action === 'index') {
        // Only do it for the index action
    }

    if ($this->params[0] ?? null) {
        // Only if first parameter exists
    }
});

To add a header to your response, you may call the setResponseHeader method.

$this->setResponseHeader('Test-Header', 'Test');

To change the status code of a response, use the setStatusCode method.

$this->setStatusCode(404);

To override the entire response, call the setResponse method, this will force the response regardless of what happens on the page's lifecycle.

$this->setResponse('Page Not Found');

You may also pass a Response object to this method.

$this->setResponse(Response::make(...));

Note: Check out the Views & Responses article for more information on building responses.