1. The user model
2. The authentication
3. Checking permissions: structure
4. Checking permissions: usage
5. Going further: access context

If you need simple Role based access control without the long RBAC process then this article is just for you. Lets jump to the point.

The user model ¶

On your user table make a column named 'roles'. Create the model accordingly. It will be named "User" here.

When you add users you can assign them a role among 'admin', 'user', 'staff' etc etc.

The authentication ¶

In the file "protected/components/UserIdentity.php" write something like:

class UserIdentity extends CUserIdentity
{
    private $id;

    public function authenticate()
    {
        $record=User::model()->findByAttributes(array('email'=>$this->username));
        if($record===null)
            $this->errorCode=self::ERROR_USERNAME_INVALID;
        else if($record->password!==md5($this->password))
            $this->errorCode=self::ERROR_PASSWORD_INVALID;
        else
        {
            $this->id=$record->id;
            $this->setState('roles', $record->roles);            
            $this->errorCode=self::ERROR_NONE;
        }
        return !$this->errorCode;
    }
 
    public function getId(){
        return $this->id;
    }
}

The important line is $this->setState('roles', $record->roles); It adds user roles to their session. You can fetch the role of the current user with Yii::app()->user->getState('roles') or simply Yii::app()->user->roles.

Checking permissions: structure ¶

Modify or create the "WebUser.php" file under the "protected/components" directory so that it overloads the checkAccess() method.

<?php 
class WebUser extends CWebUser
{
	/**
	 * Overrides a Yii method that is used for roles in controllers (accessRules).
	 *
	 * @param string $operation Name of the operation required (here, a role).
	 * @param mixed $params (opt) Parameters for this operation, usually the object to access.
	 * @return bool Permission granted?
	 */
	public function checkAccess($operation, $params=array())
	{
		if (empty($this->id)) {
			// Not identified => no rights
			return false;
		}
		$role = $this->getState("roles");
		if ($role === 'admin') {
			return true; // admin role has access to everything
		}
		// allow access if the operation request is the current user's role
		return ($operation === $role);
	}
}

You can define your own logic in this checkAccess() methods.

Make sure this class is used by Yii. The config file "protected/config/main.php" must contain:

'components' => array(
	// ...
	'user' => array(
		'class' => 'WebUser',
	),

Sidenote:
[CWebUser::checkAccess()] usually connects to the authorization system loaded in Yii. Here we are replacing it with a simple system that just deals with roles instead of the hierarchical system defined by the derivatives of [CAuthManager]. See the official tutorial, Role-Based Access Control for details.

Checking permissions: usage ¶

• In your PHP code, use Yii::app()->user->checkAccess('admin') to check if the current user has the 'admin' role. The call Yii::app()->user->checkAccess('staff') will return true if the user has the role "staff" or "admin".
• In your controller, you can filter with accessRules() using the "roles" attribute of the rule.

See examples below.

How to filter access to actions ¶

The controller must contain:

public function filters()
{
	return array(
		'accessControl', // perform access control for CRUD operations
	);
}

public function accessRules()
{	
	return array(
		array('allow',
			'action'=>array('admin'),
			'roles'=>array('staff', 'devel'),
		),
		array('deny',  // deny all users
			'users'=>array('*'),
		),
	);
}

Here the "admin" action of the controller has restricted access: only those with roles "staff" or "devel" can access it.

As described in the API doc of CAccessRule, the "roles" attribute will in fact call Yii::app()->user->checkAccess().

How to display a different menu according to roles ¶

You can also use just one menu for all users based upon different roles. for example

<?php
$user = Yii::app()->user; // just a convenience to shorten expressions
$this->widget('zii.widgets.CMenu',array(
	'items'=>array(				
		array('label'=>'Users', 'url'=>array('/manageUser/admin'), 'visible'=>$user->checkAcces('staff')),
		array('label'=>'Your Ideas', 'url'=>array('/userarea/ideaList'), 'visible'=>$user->checkAcces('normal')),
		array('label'=>'Login', 'url'=>array('/site/login'), 'visible'=>$user->isGuest),
		array('label'=>'Logout ('.Yii::app()->user->name.')', 'url'=>array('/site/logout'), 'visible'=>!$user->isGuest)
	),
));
?>

Going further: access context ¶

A very usual need is to allow a user to update its own data but not other's. In this case, the user's role is meaningless without the context: the data that will be modified.

This is why [CWebUser::checkAccess()] has an optional "$param" parameter. Now suppose we want to check is a user has the right to update a Post record. We can write:

if (Yii::app()->user->checkAccess('normal', $post)) {

Of course WebUser::checkAccess() must be extended to use this "$params" parameter. This will depend on your application's logic. For instance, it could be as simple as granting access iff $post->userId == $this->id.