title: Odoo - How to read/get field's value in another module
body: <p>I've added a new field inside hr.employee module .</p>
  
  <p>The field is : <code>'available_tickets': fields.float("Available Tickets")</code></p>
  
  <p>I need to read this field's value in another module let's say travel.request module.</p>
  
  <p>But it didn't work, can anyone help me to fix it.</p>
  
  <pre><code>class travel_request(osv.osv):
      _name = 'travel.request'
  
      def _get_available_tickets(self, cr, uid, context=None):
          ticket_obj = self.pool.get('hr.employee')
          ticket_ids = self.pool.get('hr.employee').search(cr, uid, [])
          for t_id in ticket_ids:
              ticket = ticket_obj.browse(cr, uid, t_id, context=context)
          available_tickets = ticket.available_tickets
          return available_tickets 
  
       _columns = {
           'available_tickets_id': fields.many2one('hr.employee', "Number of Available Tickets", readonly=True),
       }
       _defaults = {
           'available_tickets_id': _get_available_tickets,
       }
  
  
  class hr_employee(osv.osv):
      _inherit = "hr.employee"
      _columns = {
          'available_tickets': fields.float("Available Tickets"),
       }
  </code></pre>