Models

Models are classes designed to work with information given by or asked for by the controller. For example, you have a guestbook, the controller will ask the model to retrieve the last ten entries, the model returns those entries to the controller who passes them on to a view. The controller might also send new entries to the model, update existing ones or even delete some.

Note that Kohana doesn't force you to use models. If you choose not to use them, you are free to do so.

Kohana uses specific rules for the naming of models. These are:

• Models go into the application/models/ directory.
• Model filenames are lowercase, do not have _model appended to them and should be the singular form of the name.
• The model class name is capitalized, does have _Model appended to it and should be the singular form of the name.
• For models that use ORM, there are other, more specific, conventions.

Suppose that you have a table in the database called users (which is a plural name). The model that represents the users table would reside in the file application/models/user.php and the class would be called User_Model (which are both singular names).

The file would initially look something like this:

<?php defined('SYSPATH') or die('No direct script access.');
 
class User_Model extends Model {
 
	public function __construct()
	{
		// load database library into $this->db (can be omitted if not required)
		parent::__construct();
	}
 
}

The generally accepted way of loading a Model in Kohana is to do so within your Controller.

For instance, to load the user model (above) from application/models/user.php add the following to your controller:

$user = new User_Model;
$name = $user->get_user_name($id);  // get_user_name is a method defined in User_Model

If, for example, you use the Kohana Template_Controller and need access to your model from all descendant controllers, you can add the following to the Template_Controller constructor:

$this->user = new User_Model;

You can then access the user model from any controller that extends the Template_Controller, like this:

$name = $this->user->get_user_name($id);  // get_user_name is a method defined in User_Model

The following alternative method using the Loader library is deprecated in Kohana 2.1 and will no longer be supported in Kohana 2.2.

// Model name is called without _Model, case doesn't matter
// Deprecated as of Kohana 2.1
$this->load->model('user');
$name = $this->user->get_user_name($id);

A model might look something like this:

class User_Model extends Model {
 
        public function __construct($id = NULL)
        {
               // load database library into $this->db (can be omitted if not required)
               parent::__construct($id);
        }
 
	/**
	 * Get information about a user, given their user_id
	 * @param integer the user_id
	 * @return the result object
	 */
	public function get_user($user_id)
	{
		$this->db->where('user_id', $user_id);
		return $this->db->get('users');
	}
 
	/**
	 * Add a new user. Assumes an auto incrementing user_id in the database.
	 * @param array user data. E.g.,
	 *	array( 'name' => 'test', 'email' => '[email protected]' )
	 * @return void
	 */
	public function insert_user($data)
	{
		$this->db->insert('users', $data);
	}
 
	/**
	 * Replace user details.
	 * @param array user data. E.g.,
	 *	array( 'name' => 'test', 'email' => '[email protected]' )
	 * @return void
	 */
	public function update_user($user_id, $data)
	{
		$this->db->where('user_id', $user_id);
		$this->db->update('users', $data);
	}
 
}

Note: When utilizing data from a form always use $this→input→post('var_name', TRUE) to ensure data is sanitized before using. Learn more about the Input library.

If your model's constructor contains the line parent::__construct();, the default database functionality will be loaded into $this→db. You can use all of the database's functions with the $this→db object.

You may also specify a database group by setting the protected variable $db in your model.

protected $db = 'group_name';

Using the example model above, you can integrate this model into your controller as follows:

1. Create an instance of the model in your controller to make it accessible. This can be done directly in a controller method as $user = new User_Model. If you want the model accessible from all of your controller methods, create an instance of the model in your controller constructor: $this→user = new User_Model.
2. If you used the constructor method above, you can now retrieve user information from your database within any of your controller methods with: $user = $this→user→get_user(1). The $user variable now contains a database result set object (for the user with id = 1) that can be passed to your View.
3. If you passed the entire $user variable to your View, you can access specific user data elements within your View in the form $user→name. See Database Library for more information.

See for more information

• ORM

ORM is a special kind of model. Based on its name it will derive for example the table it is a model for, it will also have some basic functions (find($id), save()…) commonly used in a model as well as support for relationships between tables (has_many, belongs_to…). Another aspect of ORM is that it turns a record from a database into an object.