Do not keep recordsets in ormcache

Because they would be unreadable as soon as the cursor is closed.
Instead, we keep only the id and the record is browsed for every new
environment.

partner_changeset/models/changeset_field_rule.py

@@ -90,6 +90,36 @@ class ChangesetFieldRule(models.Model):
                 ]
 
     @ormcache()
+    @api.model
+    def _get_rules(self, model_name, source_model_name):
+        """ Cache rules
+
+        Keep only the id of the rules, because if we keep the recordsets
+        in the ormcache, we won't be able to browse them once their
+        cursor is closed.
+
+        The public method ``get_rules`` return the rules with the recordsets
+        when called.
+
+        """
+        model_rules = self.search(
+            [('model_id', '=', model_name),
+             '|', ('source_model_id.model', '=', source_model_name),
+                  ('source_model_id', '=', False)],
+            # using 'ASC' means that 'NULLS LAST' is the default
+            order='source_model_id ASC',
+        )
+        # model's rules have precedence over global ones so we iterate
+        # over rules which have a source model first, then we complete
+        # them with the global rules
+        result = {}
+        for rule in model_rules:
+            # we already have a model's rule
+            if result.get(rule.field_id.name):
+                continue
+            result[rule.field_id.name] = rule.id
+        return result
+
     @api.model
     def get_rules(self, model_name, source_model_name):
         """ Return the rules for a model
@@ -107,17 +137,11 @@ class ChangesetFieldRule(models.Model):
         in the key for the cache. The callers have to pass ``None`` if
         they want only global rules.
         """
-        model_rules = self.search(
-            [('model_id', '=', model_name),
-             '|', ('source_model_id.model', '=', source_model_name),
-                  ('source_model_id', '=', False)],
-            # using 'DESC' means that 'NULLS FIRST' is the default
-            order='source_model_id DESC',
-        )
-        # model's rules have precedence over global ones so we iterate
-        # over global rules first, then we update them with the rules
-        # which have a source model
-        return {rule.field_id.name: rule for rule in model_rules}
+        rules = {}
+        cached_rules = self._get_rules(model_name, source_model_name)
+        for field, rule_id in cached_rules.iteritems():
+            rules[field] = self.browse(rule_id)
+        return rules
 
     @api.model
     def create(self, vals):