what is CakePHP model alias used for?

Question

In user model:

var $hasMany = array(
        'Photo' => array(
            'className' => 'Photo',
            'foreignKey' => 'owner_id',
            ...
        ),
);

In photo model:

var $belongsTo = array(
        'Owner' => array(
            'className' => 'User',
            'foreignKey' => 'owner_id',
            ...
            ),
);

Here one user has many photos. So what my question is that here the alias name is 'Owner', which make me clear to understand the exact meaning of 'User', but is this the only reason to use alias? does it affect 'Photo' in user model? or how to use 'Owner' in/by cakephp?

I don't quite understand the meaning of alias in model. Appreciate your help!

Answer 1

Two useful scenarios for aliases:

1. Multiple foreign keys to the same model

For example, your photos table has two fields: created_user_id & modified_user_id

var $belongsTo = array(
    'CreatedUser' => array(
        'className' => 'User',
        'foreignKey' => 'created_user_id',
        ...
    ),
    'ModifiedUser' => array(
        'className' => 'User',
        'foreignKey' => 'modified_user_id',
        ...
    ),
);

2. Creating logical words specific to your application's domain

Using the conditions field in the array, you could specify different kinds of models:

var $hasMany = array(
    'ApprovedUser' => array(
        'className' => 'User',
        'foreignKey' => 'group_id',
        'conditions' => array(
            'User.approved' => 1,
            'User.deleted'  => 0
        ),
        ...
    ),
    'UnapprovedUser' => array(
        'className' => 'User',
        'foreignKey' => 'group_id',
        'conditions' => array(
            'User.approved' => 0,
            'User.deleted'  => 0
        ),
        ...
    ),
    'DeletedUser' => array(
        'className' => 'User',
        'foreignKey' => 'group_id',
        'conditions' => array('User.deleted'  => 1),
        ...
    ),
);

In the above example, a Group model has different kinds of users (approved, unapproved and deleted). Using aliases helps make your code very elegant.