title: odoo 10 - @api.onchange
body: <p>I am having difficulty in getting the @api.onchange to work.</p>
  
  <p>here are my files</p>
  
  <p><strong>init</strong>.py</p>
  
  <pre><code>from . import models
  </code></pre>
  
  <p><strong>manifest</strong>.py</p>
  
  <pre><code># -*- coding: utf-8 -*-
  {
      'name': "Sales Test",
      'description': 'test description',
      'depends': ['sale'],
      'category': 'Test',
      'data': [
          'views/templates.xml',
      ],
      'installable': True,
      'application': False,
      'auto_install': False,
  }
  </code></pre>
  
  <p><strong>init</strong>.py (file under models directory)</p>
  
  <pre><code>from . import partner
  </code></pre>
  
  <p>partner.py (file under models directory)</p>
  
  <pre><code># -*- coding: utf-8 -*-
  from odoo import models, fields, api
  
  class MyPartner(models.Model):
      _inherit = 'res.partner'
  
      @api.onchange('country_id')
      def _onchange_country_id(self):
          self.name = 'OnChange'
  
  
      @api.onchange('street', 'zip')
      def _onchange_street(self):
          self.street = 'Test Street'
          return {
              'warning': {
                  'title': "Some changes happened",
                  'message': "onchange working, bravo!!!",
              }
          },
  </code></pre>
  
  <p>the module is getting installed without any problem and the view is also been altered according to the templates.XML, but nothing happens when change happens to the fields (street, country_id or zip)</p>