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3.4.4 The App Class

Loading additional classes has become more streamlined in CakePHP. In previous versions there were different functions for loading a needed class based on the type of class you wanted to load. These functions have been deprecated, all class and library loading should be done through App::import() now. App::import() ensures that a class is only loaded once, that the appropriate parent class has been loaded, and resolves paths automatically in most cases.

3.4.4.1 Using App::import()

App::import($type, $name, $parent, $search, $file, $return);

At first glance App::import seems complex, however in most use cases only 2 arguments are required.

Here a good explanation of alternatives for being able to utilize another "Model" in your code.

  • App::import() only includes the file. So you would new to create a new instance every time. This is not recommended
  • ClassRegistry::init() loads the file, adds the instance to the a object map and returns the instance. This is an easy and convenient way to access models.
  • Controller::loadModel() Uses ClassRegistry::init() adds the model to a property of the controller and also allows persistModel to be enabled.

While you "can" do any of these things, you should ask yourself why you are creating dependencies on models that are not natural to the controller. If you "have" to do use any of these, its often best to use them in reverse order of how they were described. IE. Controller::loadModel () then CR::init() and lastly App::import().

3.4.4.2 Importing Core Libs

Core libraries such as Sanitize, and Xml can be loaded by:

App::import('Core', 'Sanitize');
  1. App::import('Core', 'Sanitize');

The above would make the Sanitize class available for use.

3.4.4.3 Importing Controllers, Models, Components, Behaviors, and Helpers

All application related class should also be loaded with App::import(). The following examples illustrate how to do so.

3.4.4.3.1 Loading Controllers

App::import('Controller', 'MyController');

Calling App::import is equivalent to require'ing the file. It is important to realize that the class subsequently needs to be initialized.

<?php
// The same as require('controllers/users_controller.php');
App::import('Controller', 'Users');

// We need to load the class
$Users = new UsersController;

// If we want the model associations, components, etc to be loaded
$Users->constructClasses();
?>
  1. <?php
  2. // The same as require('controllers/users_controller.php');
  3. App::import('Controller', 'Users');
  4. // We need to load the class
  5. $Users = new UsersController;
  6. // If we want the model associations, components, etc to be loaded
  7. $Users->constructClasses();
  8. ?>

3.4.4.3.2 Loading Models

App::import('Model', 'MyModel');

3.4.4.3.3 Loading Components

App::import('Component', 'Auth');

<?php
App::import('Component', 'Mailer');

// We need to load the class
$Mailer = new MailerComponent();

?>
  1. <?php
  2. App::import('Component', 'Mailer');
  3. // We need to load the class
  4. $Mailer = new MailerComponent();
  5. ?>

3.4.4.3.4 Loading Behaviors

App::import('Behavior', 'Tree');

3.4.4.3.5 Loading Helpers

App::import('Helper', 'Html');

3.4.4.4 Loading from Plugins

Loading classes in plugins works much the same as loading app and core classes except you must specify the plugin you are loading from.

App::import('Model', 'PluginName.Comment');
  1. App::import('Model', 'PluginName.Comment');

To load APP/plugins/plugin_name/vendors/flickr/flickr.php

App::import('Vendor', 'PluginName.flickr/flickr');
  1. App::import('Vendor', 'PluginName.flickr/flickr');

3.4.4.5 Loading Vendor Files

The vendor() function has been deprecated. Vendor files should now be loaded through App::import() as well. The syntax and additional arguments are slightly different, as vendor file structures can differ greatly, and not all vendor files contain classes.

The following examples illustrate how to load vendor files from a number of path structures. These vendor files could be located in any of the vendor folders.

3.4.4.5.1 Vendor examples

To load vendors/geshi.php

App::import('Vendor', 'geshi');
  1. App::import('Vendor', 'geshi');

To load vendors/flickr/flickr.php

App::import('Vendor', 'flickr/flickr');
  1. App::import('Vendor', 'flickr/flickr');

To load vendors/some.name.php

App::import('Vendor', 'SomeName', array('file' => 'some.name.php'));
  1. App::import('Vendor', 'SomeName', array('file' => 'some.name.php'));

To load vendors/services/well.named.php

App::import('Vendor', 'WellNamed', array('file' => 'services'.DS.'well.named.php'));
  1. App::import('Vendor', 'WellNamed', array('file' => 'services'.DS.'well.named.php'));

It wouldn't make a difference if your vendor files are inside your /app/vendors directory. Cake will automatically find it.

To load app/vendors/vendorName/libFile.php

App::import('Vendor', 'aUniqueIdentifier', array('file' =>'vendorName'.DS.'libFile.php'));
  1. App::import('Vendor', 'aUniqueIdentifier', array('file' =>'vendorName'.DS.'libFile.php'));
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