title: openerp ValueError: too many values to unpack
body: <p>i am trying to get the current user name that make validate to invoice and i am writing this code </p>
  
  <pre><code>class account_invoice(orm.Model):
  
      _name="account.invoice"
      _inherit="account.invoice"
  
  
      def _get_validated_user(self, cr, uid, field_name, arg, context):
          result={}
          current_user=self.pool.get('res.users').browse(cr, uid, uid, context=context)
          for user_id in current_user:
              if uid in current_user.id:
                  result[current_user.id]=current_user.login
          # inv_obj=self.browse(cr,uid,ids)
          # user_name=inv_obj.write(cr, uid, {'validated_by': current_user})
  
  
      _columns = {
          'validated_by': fields.char('Validated_By',size=30),
  
          'user_name': fields.function(
              _get_validated_user,
              type='char',
              method=True,
              string='User Name'),
      }
  </code></pre>
  
  <p>when i try to install my custom module i get this error </p>
  
  <blockquote>
    <p>ValueError: too many values to unpack</p>
  </blockquote>
  
  <p>where is the error ?? </p>