title: creating new module that inherits from custom modules
body: <p>I was trying to add some fields to my new module which contains 5 classes 2 of them inherit from custom modules ( product.template/res.partner) those classes are related with relational fields, I have tried so many ways to make it work and correct many errors but now stuck with this one  </p>
  
  <pre><code>ParseError: "Invalid view definition
  
  details of error :
  the field `date_intv` doesn't existe 
  Contexte de l'erreur :
  Vue `intervention.form`
  [view_id: 2592, xml_id: n/a, model: c.intervention, parent_id: n/a]
  None" while parsing file:///C:/Program Files (x86)/Odoo 9.0-20151125/server/openerp/addons/Gestion_CVT/fileds_intervention.xml:5, near
  &lt;record model="ir.ui.view" id="intervention_form"&gt;
              &lt;field name="name"&gt;intervention.form&lt;/field&gt;
              &lt;field name="model"&gt;c.intervention&lt;/field&gt;
              &lt;field name="type"&gt;form&lt;/field&gt;
              &lt;field name="arch" type="xml"&gt;
                  &lt;form string="formulaire"&gt;
                      &lt;field name="type_int"/&gt;
                      &lt;field name="properties4"/&gt;
                      &lt;field name="date_intv"/&gt;
                  &lt;/form&gt;
              &lt;/field&gt;
          &lt;/record&gt;
  </code></pre>
  
  <p>manchening also that I have already used the osv.osv but didn't work with the equipement class because I was adding class by class so  now I changed them all to models.Model so here is my .py file</p>
  
  <pre><code># -*- coding: utf-8 -*-
  from openerp import models, fields, api
  class centre(models.Model):
     _name = 'res.partner'
     _inherit = ['res.partner']
     rs_ctr = fields.Char(string='Réseau')
     nb_ligne = fields.Integer(string='Lignes')
     n_agr = fields.Integer(string='N° d\'agrèment')
     chef = fields.Char(string='Chef centre')
     prp = fields.Char(string='Propriétaire')
     equipement_id = fields.Many2one('product.template','Equipements',select=True)
     properties1 = fields.One2many('product.template','centre_id','Centres')
  centre() 
  class equipement(models.Model):
     _name = 'product.template'
     _inherit = ['product.template']
     num_ligne = fields.Integer(string='N° ligne')
     model_mat = fields.Char(string='Model de materiel')
     centre_id = fields.Many2one('res.partner','Centres',select=True) 
     marque_id = fields.Many2one('c.marque','Marques',select=True)
     properties2 = fields.One2many('c.eptinv','equipement_id','Equipements')
  equipement()    
  class marque(models.Model):
     _name = 'c.marque'
     _description = 'Marques' 
     name = fields.Char(string='Nom')
     nom_four = fields.Char(string='Fournisseur')  
     properties3 = fields.One2many('product.template','marque_id','Marques')
  marque()
  class intervention(models.Model):
     _name = 'c.intervention'
     _inherits = {'c.eptinv': 'date_intv'}
     STATE_SELECTION =  [('c','Corrective'),('p','Préventive')]
     _description = 'Interventions'
     name = fields.Char(string='Nom')
     type_int = fields.Selection(STATE_SELECTION,'Type d\'intervention')
     properties4 = fields.One2many('c.eptinv','intervention_id','Interventions')
  intervention()      
  class eptinv(models.Model):
     _name = 'c.eptinv'
     _description = 'EptInv' 
     date_intv = fields.Date(string='Date d\'intervention')
     equipement_id = fields.Many2one('product.template','Equipements')  
     intervention_id = fields.Many2one('c.intervention','Interventions')
  eptinv()
  </code></pre>