Difference between #8 and #7 of Simple RBAC

unchanged
Title
Simple RBAC
unchanged
Category
Tutorials
unchanged
Tags
Simple RBAC, Role based access control, roles, Authentication, Role based menu
changed
Content
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:

~~~
[php]
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]
<?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:

~~~
[php]
'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](http://www.yiiframework.com/doc/guide/1.1/en/topics.auth#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:

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

public function accessRules()
{	
	return array(
		array('allow',
			'action'=>array('admin'),			'actions'=>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](http://www.yiiframework.com/doc/api/1.1/CAccessRule#roles-detail),
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]
<?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->checkAccess('staff')),
		array('label'=>'Your Ideas', 'url'=>array('/userarea/ideaList'),
'visible'=>$user->checkAccess('normal')),
		array('label'=>'Login', 'url'=>array('/site/login'),
'visible'=>$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:
~~~
[php]
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`.