Add on_delete to ModelStorage

trytond/CHANGELOG

@@ -1,3 +1,4 @@
+* Add on_delete to ModelStorage
 * Add check_modification to ModelStorage
 * Add on_modification to ModelStorage
 * Add preprocess_values to ModelStorage

trytond/doc/ref/models.rst

@@ -436,6 +436,10 @@ Class methods:
 
       It is used to trigger actions based on what has been modified.
 
+.. classmethod:: ModelStorage.on_delete(records)
+
+   Returns a list of methods to call once the records have been deleted.
+
 .. classmethod:: ModelStorage.copy(records[, default])
 
    Duplicate the records.

trytond/trytond/model/modelsql.py

@@ -1472,7 +1472,7 @@ class ModelSQL(ModelStorage):
         cursor = transaction.connection.cursor()
         pool = Pool()
 
-        ids = cls._before_delete(records)
+        ids, on_delete = cls._before_delete(records)
         if not ids:
             return
 
@@ -1581,7 +1581,7 @@ class ModelSQL(ModelStorage):
 
         cls._update_mptt(list(tree_ids.keys()), list(tree_ids.values()))
 
-        cls._after_delete(ids)
+        cls._after_delete(ids, on_delete)
 
     @classmethod
     def __check_domain_rule(cls, ids, mode):

trytond/trytond/model/modelstorage.py

@@ -430,6 +430,7 @@ class ModelStorage(Model):
                 ModelData.clean(records)
             if check_access:
                 cls.log(records, 'delete')
+            on_delete = cls.on_delete(records)
             cls.on_modification('delete', records)
 
             triggers = Trigger.get_triggers(cls.__name__, 'delete')
@@ -469,7 +470,7 @@ class ModelStorage(Model):
                     except ValueError:
                         break
         transaction.delete_records[cls.__name__].update(ids)
-        return ids
+        return ids, on_delete
 
     @classmethod
     def delete(cls, records):
@@ -478,12 +479,14 @@ class ModelStorage(Model):
 
     @classmethod
     @without_check_access
-    def _after_delete(cls, ids):
+    def _after_delete(cls, ids, on_delete):
         pool = Pool()
         Translation = pool.get('ir.translation')
         if any(getattr(f, 'translate', False) and not hasattr(f, 'set')
                 for f in cls._fields.values()):
             Translation.delete_ids(cls.__name__, 'model', ids)
+        for meth in on_delete:
+            meth()
 
     @classmethod
     def check_modification(cls, mode, records, values=None, external=False):
@@ -493,6 +496,10 @@ class ModelStorage(Model):
     def on_modification(cls, mode, records, field_names=None):
         assert mode in {'create', 'write', 'delete'}
 
+    @classmethod
+    def on_delete(cls, records):
+        return []
+
     @classmethod
     def copy(cls, records, default=None):
         '''