Kohana 3: getting related data from an ORM model

Question

When using Kohana 3's ORM models, what is the best way to get data from fields of related models? For example, I have an employee, who has one company, and has many assignments. How would I go about getting data from fields in the company model and assignment model(s) (i.e. in a has_one and a has_many relationship)?

EDIT: as requested, here are the models in question.

User Model

class Model_User extends ORM {
    protected $_table_name = 'user';
    protected $_primary_key = 'id';
    protected $_primary_val = 'username';
    protected $_has_many = array(
        'task' => array(
            'model' => 'task',
            'foreign_key' => 'user',
        ),
    );
    protected $_belongs_to = array(
        'company' => array(
            'model' => 'company',
            'foreign_key' => 'company'
        ),
    );

Task Model

class Model_Task extends ORM {
    protected $_table_name = 'tasks';
    protected $_primary_key = 'id';
    protected $_primary_val = 'name';
    protected $_belongs_to = array(
        'project' => array(
            'model' => 'project',
            'foreign_key' => 'project'
        ),
        'user' => array(
            'model' => 'user',
            'foreign_key' => 'user'
        ),
    );

Company Model

class Model_Company extends ORM {
    protected $_table_name = 'companies';
    protected $_primary_key = 'id';
    protected $_primary_val = 'name';
    protected $_has_many = array(
        'user' => array(
            'model' => 'user',
            'foreign_key' => 'company'
        ),
    );

}

Code Throwing Error, From Controller

$users = ORM::factory('user')->find_all();
$list = array();
foreach($users as $user) {
   $list[$user->id] = array(
     'username' => $user->username,
     'email' => $user->email,
     'company' => $user->company->name  //error:Trying to get property of non-object
   )
}

Answer 1

To get the company you would do

$employee->company

So you can get the company properties with

$employee->company->property

To get the assignments you would do

$employee->company->assignments->find_all();

You can also chain other query methods such as ->where() before you call find_all() or find().

Answer 2

Well, if your employee can only belong to one company then to access the company would be done like so:

$company = $employee->company;

You can then access $company properties (fields) like you would with any other model.

I believe there's no limit to the depth of relations you can access, so doing

$assignments $employee->company->assignments->find_all();

is possible. Make note of the find_all(); where you expect to have more than one record returned.

Answer 3

1. Use plural forms for multiple relationships (has_many). Company has many users, user has many tasks etc. Its not critical but recommended.
2. What is the column name for company in the users table? Seems like its a company instead of company_id. If so, you can rename this foreign key or relation name.