Controllers

Introduction

A controller is used to manage the logic for a part of your application. Most commonly, controllers are used to manage the logic for a single model. For example, if you were building a site for an online bakery, you might have a RecipesController and a IngredientsController managing your recipes and their ingredients. In CakePHP, controllers are named after the model they handle, in plural form.

The Recipe model is handled by the RecipesController, the Product model is handled by the ProductsController, and so on.

Your application’s controllers are classes that extend the CakePHP AppController class, which in turn extends a core Controller class, which are part of the CakePHP library. The AppController class can be defined in /app/app_controller.php and it should contain methods that are shared between all of your application’s controllers.

Controllers can include any number of methods which are usually referred to as actions. Actions are controller methods used to display views. An action is a single method of a controller.

CakePHP’s dispatcher calls actions when an incoming request matches a URL to a controller’s action (refer to Configuration for an explanation on how controller actions and parameters are mapped from the URL).

Returning to our online bakery example, our RecipesController might contain the view(), share(), and search() actions. The controller would be found in /app/controllers/recipes_controller.php and contain:

<?php

# /app/controllers/recipes_controller.php

class RecipesController extends AppController {
    function view($id)     {
        //action logic goes here..
    }

    function share($customer_id, $recipe_id) {
        //action logic goes here..
    }

    function search($query) {
        //action logic goes here..
    }
}

?>

In order for you to use a controller effectively in your own application, we’ll cover some of the core attributes and methods provided by CakePHP’s controllers.

The App Controller

As stated in the introduction, the AppController class is the parent class to all of your application’s controllers. AppController itself extends the Controller class included in the CakePHP core library.

As such, AppController is defined in /cake/libs/controller/app_controller.php or /app/app_controller.php. If /app/app_controller.php does not exist then copy from /cake location before customizing for application.

Do not customize cake frameworks controller: /cake/libs/controller/app_controller.php. These changes will be overwritten during upgrades.

It contains a skeleton definition:

<?php
class AppController extends Controller {
}
?>

Controller attributes and methods created in your AppController will be available to all of your application’s controllers. It is the ideal place to create code that is common to all of your controllers. Components (which you’ll learn about later) are best used for code that is used in many (but not necessarily all) controllers.

While normal object-oriented inheritance rules apply, CakePHP also does a bit of extra work when it comes to special controller attributes, like the list of components or helpers used by a controller. In these cases, AppController value arrays are merged with child controller class arrays.

CakePHP merges the following variables from the AppController to your application’s controllers:

  • $components
  • $helpers
  • $uses

Remember to add the default Html and Form helpers, if you define var $helpers in your AppController

Please also remember to call AppController’s callbacks within child controller callbacks for best results:

function beforeFilter(){
    parent::beforeFilter();
}

The Pages Controller

CakePHP core ships with a default controller called the Pages Controller (cake/libs/controller/pages_controller.php). The home page you see after installation is generated using this controller. It is generally used to serve static pages. Eg. If you make a view file app/views/pages/about_us.ctp you can access it using url http://example.com/pages/about_us

When you “bake” an app using CakePHP’s console utility the pages controller is copied to your app/controllers/ folder and you can modify it to your needs if required. Or you could just copy the pages_controller.php from core to your app.

Do not directly modify ANY file under the cake folder to avoid issues when updating the core in future

Controller Attributes

For a complete list of controller attributes and their descriptions visit the CakePHP API. Check out http://api.cakephp.org/class/controller.

$name

PHP4 users should start out their controller definitions using the $name attribute. The $name attribute should be set to the name of the controller. Usually this is just the plural form of the primary model the controller uses. This takes care of some PHP4 classname oddities and helps CakePHP resolve naming.

<?php

#   $name controller attribute usage example

class RecipesController extends AppController {
   var $name = 'Recipes';
}

?>

$components, $helpers and $uses

The next most often used controller attributes tell CakePHP what helpers, components, and models you’ll be using in conjunction with the current controller. Using these attributes make MVC classes given by $components and $uses available to the controller as class variables ($this->ModelName, for example) and those given by $helpers to the view as an object reference variable ($helpername).

Each controller has some of these classes available by default, so you may not need to configure your controller at all.

Controllers have access to their primary model available by default. Our RecipesController will have the Recipe model class available at $this->Recipe, and our ProductsController also features the Product model at $this->Product. However, when allowing a controller to access additional models through the $uses variable, the name of the current controller’s model must also be included. This is illustrated in the example below.

The Html and Form Helpers are always available by default. But if you choose to define your own $helpers array in AppController, make sure to include Html and Form if you want them still available by default in your own Controllers. The Session Helper and Component may be useful to manage sessions and state in your application. To learn more about these classes, be sure to check out their respective sections later in this manual.

Let’s look at how to tell a CakePHP controller that you plan to use additional MVC classes.

<?php
class RecipesController extends AppController {
    var $name = 'Recipes';

    var $uses = array('Recipe', 'User');
    var $helpers = array('Ajax');
    var $components = array('Email');
}
?>

Each of these variables are merged with their inherited values, therefore it is not necessary (for example) to redeclare the Form helper, or anything that is declared in your App controller.

If you do not wish to use a Model in your controller, set var $uses = array(). This will allow you to use a controller without a need for a corresponding Model file.

It’s bad practice to just add all the models your controller uses to the $uses array. Check Models to see how to properly access associated and unassociated models respectively.

The Parameters Attribute ($params)

Controller parameters are available at $this->params in your CakePHP controller. This variable is used to provide access to information about the current request. The most common usage of $this->params is to get access to information that has been handed to the controller via POST or GET operations.

form

$this->params['form']

Any POST data from any form is stored here, including information also found in $_FILES.

admin

$this->params['admin']

Is set to 1 if the current action was invoked via admin routing.

bare

$this->params['bare']

Stores 1 if the current layout is empty, 0 if not.

isAjax

$this->params['isAjax']

Stores 1 if the current request is an ajax call, 0 if not. This variable is only set if the RequestHandler Component is being used in the controller.

controller

$this->params['controller']

Stores the name of the current controller handling the request. For example, if the URL /posts/view/1 was requested, $this->params['controller'] would equal “posts”.

action

$this->params['action']

Stores the name of the current action handling the request. For example, if the URL /posts/view/1 was requested, $this->params['action'] would equal “view”.

pass

$this->params['pass']

Returns an array (numerically indexed) of URL parameters after the Action.

// URL: /posts/view/12/print/narrow

Array
(
    [0] => 12
    [1] => print
    [2] => narrow
)

url

$this->params['url']

Stores the current URL requested, along with key-value pairs of get variables. For example, if the URL /posts/view/?var1=3&var2=4 was called, $this->params['url'] would contain:

[url] => Array
(
    [url] => posts/view
    [var1] => 3
    [var2] => 4
)

data

$this->data

Used to handle POST data sent from the FormHelper forms to the controller.

// The FormHelper is used to create a form element:
echo $this->Form->text('User.first_name');

Which when rendered, looks something like:

<input name="data[User][first_name]" value="" type="text" />

When the form is submitted to the controller via POST, the data shows up in this->data

//The submitted first name can be found here:
$this->data['User']['first_name'];

prefix

$this->params['prefix']

Set to the routing prefix. For example, this attribute would contain the string “admin” during a request to /admin/posts/someaction.

named

$this->params['named']

Stores any named parameters in the url query string in the form /key:value/. For example, if the URL /posts/view/var1:3/var2:4 was requested, $this->params['named'] would be an array containing:

[named] => Array
(
    [var1] => 3
    [var2] => 4
)

Other Attributes

While you can check out the details for all controller attributes in the API, there are other controller attributes that merit their own sections in the manual.

The $cacheAction attribute aids in caching views, and the $paginate attribute is used to set pagination defaults for the controller. For more information on how to use these attributes, check out their respective sections later on in this manual.

persistModel

Stub. Update Me!

Used to create cached instances of models a controller uses. When set to true, all models related to the controller will be cached. This can increase performance in many cases.

Controller Methods

For a complete list of controller methods and their descriptions visit the CakePHP API. Check out http://api13.cakephp.org/class/controller.

Interacting with Views

Controllers interact with the view in a number of ways. First they are able to pass data to the views, using set(). You can also decide which view class to use, and which view file should be rendered from the controller.

set

set(string $var, mixed $value)

The set() method is the main way to send data from your controller to your view. Once you’ve used set(), the variable can be accessed in your view.

<?php

//First you pass data from the controller:

$this->set('color', 'pink');

//Then, in the view, you can utilize the data:
?>

You have selected <?php echo $color; ?> icing for the cake.

The set() method also takes an associative array as its first parameter. This can often be a quick way to assign a set of information to the view.

Array keys will no longer be inflected before they are assigned to the view (‘underscored_key’ does not become ‘underscoredKey’ anymore, etc.):

<?php

$data = array(
    'color' => 'pink',
    'type' => 'sugar',
    'base_price' => 23.95
);

//make $color, $type, and $base_price
//available to the view:

$this->set($data);

?>

The attribute $pageTitle no longer exists, use set() to set the title

<?php
$this->set('title_for_layout', 'This is the page title');
?>

render

render(string $action, string $layout, string $file)

The render() method is automatically called at the end of each requested controller action. This method performs all the view logic (using the data you’ve given in using the set() method), places the view inside its layout and serves it back to the end user.

The default view file used by render is determined by convention. If the search() action of the RecipesController is requested, the view file in /app/views/recipes/search.ctp will be rendered.

class RecipesController extends AppController {
...
    function search() {
        // Render the view in /views/recipes/search.ctp
        $this->render();
    }
...
}

Although CakePHP will automatically call it (unless you’ve set $this->autoRender to false) after every action’s logic, you can use it to specify an alternate view file by specifying an action name in the controller using $action.

If $action starts with ‘/’ it is assumed to be a view or element file relative to the /app/views folder. This allows direct rendering of elements, very useful in ajax calls.

// Render the element in /views/elements/ajaxreturn.ctp
$this->render('/elements/ajaxreturn');

You can also specify an alternate view or element file using the third parameter, $file. When using $file, don’t forget to utilize a few of CakePHP’s global constants (such as VIEWS).

The $layout parameter allows you to specify the layout the view is rendered in.

Rendering a specific view

In your controller you may want to render a different view than what would conventionally be done. You can do this by calling render() directly. Once you have called render() CakePHP will not try to re-render the view.

class PostsController extends AppController {
    function my_action() {
        $this->render('custom_file');
    }
}

This would render app/views/posts/custom_file.ctp instead of app/views/posts/my_action.ctp

Flow Control

redirect

redirect(mixed $url, integer $status, boolean $exit)

The flow control method you’ll use most often is redirect(). This method takes its first parameter in the form of a CakePHP-relative URL. When a user has successfully placed an order, you might wish to redirect them to a receipt screen.

function placeOrder() {

    //Logic for finalizing order goes here

    if($success) {
        $this->redirect(array('controller' => 'orders', 'action' => 'thanks'));
    } else {
        $this->redirect(array('controller' => 'orders', 'action' => 'confirm'));
    }
}

You can also use a relative or absolute URL as the $url argument:

$this->redirect('/orders/thanks');
$this->redirect('http://www.example.com');

You can also pass data to the action:

$this->redirect(array('action' => 'edit', $id));

The second parameter of redirect() allows you to define an HTTP status code to accompany the redirect. You may want to use 301 (moved permanently) or 303 (see other), depending on the nature of the redirect.

The method will issue an exit() after the redirect unless you set the third parameter to false.

If you need to redirect to the referer page you can use:

$this->redirect($this->referer());

flash

flash(string $message, string $url, integer $pause, string $layout)

Like redirect(), the flash() method is used to direct a user to a new page after an operation. The flash() method is different in that it shows a message before passing the user on to another URL.

The first parameter should hold the message to be displayed, and the second parameter is a CakePHP-relative URL. CakePHP will display the $message for $pause seconds before forwarding the user on.

If there’s a particular template you’d like your flashed message to use, you may specify the name of that layout in the $layout parameter.

For in-page flash messages, be sure to check out SessionComponent’s setFlash() method.

Callbacks

CakePHP controllers come fitted with callbacks you can use to insert logic just before or after controller actions are rendered.

beforeFilter()

This function is executed before every action in the controller. It’s a handy place to check for an active session or inspect user permissions.

beforeRender()

Called after controller action logic, but before the view is rendered. This callback is not used often, but may be needed if you are calling render() manually before the end of a given action.

afterFilter()

Called after every controller action, and after rendering is complete. This is the last controller method to run.

CakePHP also supports callbacks related to scaffolding.

_beforeScaffold($method)

$method name of method called example index, edit, etc.

_afterScaffoldSave($method)

$method name of method called either edit or update.

_afterScaffoldSaveError($method)

$method name of method called either edit or update.

_scaffoldError($method)

$method name of method called example index, edit, etc.

Other Useful Methods

constructClasses

This method loads the models required by the controller. This loading process is done by CakePHP normally, but this method is handy to have when accessing controllers from a different perspective. If you need CakePHP in a command-line script or some other outside use, constructClasses() may come in handy.

referer

string referer(mixed $default = null, boolean $local = false)

Returns the referring URL for the current request. Parameter $default can be used to supply a default URL to use if HTTP_REFERER cannot be read from headers. So, instead of doing this:

<?php
class UserController extends AppController {
    function delete($id) {
        // delete code goes here, and then...
        if ($this->referer() != '/') {
            $this->redirect($this->referer());
        } else {
            $this->redirect(array('action' => 'index'));
        }
    }
}
?>

you can do this:

<?php
class UserController extends AppController {
    function delete($id) {
        // delete code goes here, and then...
        $this->redirect($this->referer(array('action' => 'index')));
    }
}
?>

If $default is not set, the function defaults to the root of your domain - ‘/’.

Parameter $local if set to true, restricts referring URLs to local server.

disableCache

Used to tell the user’s browser not to cache the results of the current request. This is different than view caching, covered in a later chapter.

The headers sent to this effect are:

Expires: Mon, 26 Jul 1997 05:00:00 GMT

Last-Modified: [current datetime] GMT

Cache-Control: no-store, no-cache, must-revalidate

Cache-Control: post-check=0, pre-check=0

Pragma: no-cache

postConditions

postConditions(array $data, mixed $op, string $bool, boolean $exclusive)

Use this method to turn a set of POSTed model data (from HtmlHelper-compatible inputs) into a set of find conditions for a model. This function offers a quick shortcut on building search logic. For example, an administrative user may want to be able to search orders in order to know which items need to be shipped. You can use CakePHP’s Form- and HtmlHelpers to create a quick form based on the Order model. Then a controller action can use the data posted from that form to craft find conditions:

function index() {
    $conditions = $this->postConditions($this->data);
    $orders = $this->Order->find("all",compact('conditions'));
    $this->set('orders', $orders);
}

If $this->data[‘Order’][‘destination’] equals “Old Towne Bakery”, postConditions converts that condition to an array compatible for use in a Model->find() method. In this case, array(“Order.destination” => “Old Towne Bakery”).

If you want use a different SQL operator between terms, supply them using the second parameter.

/*
Contents of $this->data
array(
    'Order' => array(
        'num_items' => '4',
        'referrer' => 'Ye Olde'
    )
)
*/

//Let’s get orders that have at least 4 items and contain ‘Ye Olde’
$conditions=$this->postConditions(
    $this->data,
    array(
        'num_items' => '>=',
        'referrer' => 'LIKE'
    )
);
$orders = $this->Order->find("all",compact('conditions'));

The third parameter allows you to tell CakePHP what SQL boolean operator to use between the find conditions. String like ‘AND’, ‘OR’ and ‘XOR’ are all valid values.

Finally, if the last parameter is set to true, and the $op parameter is an array, fields not included in $op will not be included in the returned conditions.

paginate

This method is used for paginating results fetched by your models. You can specify page sizes, model find conditions and more. See the pagination section for more details on how to use paginate.

requestAction

requestAction(string $url, array $options)

This function calls a controller’s action from any location and returns data from the action. The $url passed is a CakePHP-relative URL (/controllername/actionname/params). To pass extra data to the receiving controller action add to the $options array.

You can use requestAction() to retrieve a fully rendered view by passing ‘return’ in the options: requestAction($url, array('return'));. It is important to note that making a requestAction using ‘return’ from a controller method can cause script and css tags to not work correctly.

If used without caching requestAction can lead to poor performance. It is rarely appropriate to use in a controller or model.

requestAction is best used in conjunction with (cached) elements – as a way to fetch data for an element before rendering. Let’s use the example of putting a “latest comments” element in the layout. First we need to create a controller function that will return the data.

// controllers/comments_controller.php
class CommentsController extends AppController {
    function latest() {
        $comments = $this->Comment->find('all', array('order' => 'Comment.created DESC', 'limit' => 10));
        if (!empty($this->params['requested'])) {
            return $comments;
        } else {
            $this->set(compact('comments'));
        }
    }
}

When an action is called through requestAction $this->params['requested'] is set to 1 as an indicator. So checking that you can either return the required data else set it a view variable like you normally would. This helps keep things DRY.

If we now create a simple element to call that function:

// views/elements/latest_comments.ctp

$comments = $this->requestAction('/comments/latest');
foreach($comments as $comment) {
    echo $comment['Comment']['title'];
}

We can then place that element anywhere at all to get the output using:

echo $this->element('latest_comments');

Written in this way, whenever the element is rendered, a request will be made to the controller to get the data, the data will be processed, and returned. However in accordance with the warning above it’s best to make use of element caching to prevent needless processing. By modifying the call to element to look like this:

echo $this->element('latest_comments', array('cache' => '+1 hour'));

The requestAction call will not be made while the cached element view file exists and is valid.

In addition, requestAction now takes array based cake style urls:

echo $this->requestAction(array('controller' => 'articles', 'action' => 'featured'), array('return'));

This allows the requestAction call to bypass the usage of Router::url which can increase performance. The url based arrays are the same as the ones that HtmlHelper::link uses with one difference - if you are using named or passed parameters, you must put them in a second array and wrap them with the correct key. This is because requestAction merges the named args array (requestAction’s 2nd parameter) with the Controller::params member array and does not explicitly place the named args array into the key ‘named’; Additional members in the $option array will also be made available in the requested action’s Controller::params array.

echo $this->requestAction('/articles/featured/limit:3');
echo $this->requestAction('/articles/view/5');

As an array in the requestAction would then be:

echo $this->requestAction(array('controller' => 'articles', 'action' => 'featured'), array('named' => array('limit' => 3)));

echo $this->requestAction(array('controller' => 'articles', 'action' => 'view'), array('pass' => array(5)));

Unlike other places where array urls are analogous to string urls, requestAction treats them differently.

When using an array url in conjunction with requestAction() you must specify all parameters that you will need in the requested action. This includes parameters like $this->data and $this->params['form']. In addition to passing all required parameters, named and pass parameters must be done in the second array as seen above.

loadModel

loadModel(string $modelClass, mixed $id)

The loadModel function comes handy when you need to use a model which is not the controller’s default model or its associated model.

$this->loadModel('Article');
$recentArticles = $this->Article->find('all', array('limit' => 5, 'order' => 'Article.created DESC'));
$this->loadModel('User', 2);
$user = $this->User->read();