[IMP] orm/inherits: check that m2o fields implementing _inherits are marked required with ondelete cascade

Fix the issue if one is detected, either adding the missing field or forcing the attributes

bzr revid: odo@openerp.com-20100812200848-l8q72d44237gn5uk

bin/osv/orm.py

@@ -2616,7 +2616,7 @@ class orm(orm_template):
                     self._columns[field['name']] = getattr(fields, field['ttype'])(field['relation'], _rel_name, 'id1', 'id2', **attrs)
                 else:
                     self._columns[field['name']] = getattr(fields, field['ttype'])(**attrs)
-
+        self._inherits_check()
         self._inherits_reload()
         if not self._sequence:
             self._sequence = self._table+'_id_seq'
@@ -2734,6 +2734,17 @@ class orm(orm_template):
         self._inherit_fields = res
         self._inherits_reload_src()
 
+    def _inherits_check(self):
+        for table, field_name in self._inherits.items():
+            if field_name not in self._columns:
+                logging.getLogger('init').info('Missing many2one field definition for _inherits reference "%s" in "%s", using default one.' % (field_name, self._name))
+                self._columns[field_name] =  fields.many2one(table, string="Automatically created field to link to parent %s" % table,
+                                                             required=True, ondelete="cascade")
+            elif not self._columns[field_name].required or self._columns[field_name].ondelete.lower() != "cascade":
+                logging.getLogger('init').warning('Field definition for _inherits reference "%s" in "%s" must be marked as "required" with ondelete="cascade", forcing it.' % (field_name, self._name))
+                self._columns[field_name].required = True
+                self._columns[field_name].ondelete = "cascade"
+
     #def __getattr__(self, name):
     #    """
     #    Proxies attribute accesses to the `inherits` parent so we can call methods defined on the inherited parent