I have an animals model, a cage model and a relational model between users(workers) and cages:

cage_manager.py:

class animal(osv.osv):
 _name = 'animal'
 _columns = {
 'name': fields.char('Animal Name', size=100),
 'cage_id': fields.many2one('cage', required=True, ondelete='cascade', string="Cage")
 }



class cage(osv.osv):
 _name = 'cage'
 _columns = {
 'name': fields.char('Cage Name', size=100),
 'animals': fields.one2many('animal', 'cage_id', string="Animals"),
 'workers': fields.one2many('cage.user.relation', 'cage_id', string="Workers")
 }



class cage_user_relation(osv.osv):

 _name = 'cage.user.rel'
 _columns = {
 'cage_id': fields.many2one('cage', required=True, ondelete='cascade', string="Cage"),
 'user_id': fields.many2one('res.users', required=True, ondelete='cascade', string="Worker"),
 }

I have this in the cage_manager.xml:

<record id="view_cage_manager_tree" model="ir.ui.view">
 <field name="name">cage.tree</field>
 <field name="model">cage</field>
 <field name="type">tree</field>
 <field name="arch" type="xml">
 <tree string="cage_tree">
 <field name="name"/>
 <field name="animals"/>
 <field name="workers"/>
 </tree>
 </field>
</record>

I want to allow each worker to see only the cages associated to him. (The administrator can see every cage)

I want something like this:

<record id='action_menu_cage_manager' model='ir.actions.act_window'>
 <field name="name">Cages Manager</field>
 <field name="res_model">cage</field>
 <field name="view_type">form</field>
 <field name="view_mode">tree,form</field>
 <field name="domain">[
 ('id', 'in', 'cages_of_current_worker()')
 ]</field>
</record>

But I don't know how and where to implement the cages_of_current_worker() function