Only allow models to be registered for tracking once

Author: macro1

simple_history/__init__.py

@@ -21,13 +21,14 @@ def register(
     `HistoricalManager` instance directly to `model`.
     """
     from . import models
-    if model._meta.db_table not in models.registered_models:
-        if records_class is None:
-            records_class = models.HistoricalRecords
-        records = records_class(**records_config)
-        records.manager_name = manager_name
-        records.table_name = table_name
-        records.module = app and ("%s.models" % app) or model.__module__
-        records.add_extra_methods(model)
-        records.finalize(model)
-        models.registered_models[model._meta.db_table] = model
+
+    if records_class is None:
+        records_class = models.HistoricalRecords
+
+    records = records_class(**records_config)
+    records.manager_name = manager_name
+    records.table_name = table_name
+    records.module = app and ("%s.models" % app) or model.__module__
+    records.add_extra_methods(model)
+    records.finalize(model)
+    models.registered_models[model._meta.db_table] = model

simple_history/exceptions.py

@@ -0,0 +1,7 @@
+"""
+django-simple-history exceptions and warnings classes.
+"""
+
+class MultipleRegistrationsError(Exception):
+    """The model has been registered to have history tracking more than once"""
+    pass

simple_history/models.py

@@ -26,6 +26,7 @@
     add_introspection_rules(
         [], ["^simple_history.models.CustomForeignKeyField"])
 
+from . import exceptions
 from .manager import HistoryDescriptor
 
 registered_models = {}
@@ -75,10 +76,15 @@ def finalize(self, sender, **kwargs):
         except AttributeError:  # called via `register`
             pass
         else:
-            if not hint_class is sender:  # set in concrete
+            if hint_class is not sender:  # set in concrete
                 if not (hint_class._meta.abstract
                         and issubclass(sender, hint_class)):  # set in abstract
                     return
+        if hasattr(sender._meta, 'simple_history_manager_attribute'):
+            raise exceptions.MultipleRegistrationsError('{}.{} registered multiple times for history tracking.'.format(
+                sender._meta.app_label,
+                sender._meta.object_name,
+            ))
         history_model = self.create_history_model(sender)
         module = importlib.import_module(self.module)
         setattr(module, history_model.__name__, history_model)

simple_history/tests/tests/test_models.py

@@ -10,8 +10,8 @@
 from django.test import TestCase
 from django.core.files.base import ContentFile
 
+from simple_history import exceptions, register
 from simple_history.models import HistoricalRecords, convert_auto_field
-from simple_history import register
 from ..models import (
     AdminProfile, Bookcase, MultiOneToOne, Poll, Choice, Voter, Restaurant,
     Person, FileModel, Document, Book, HistoricalPoll, Library, State,
@@ -332,12 +332,8 @@ def test_register_separate_app(self):
         self.assertEqual(len(user.histories.all()), 1)
 
     def test_reregister(self):
-        register(Restaurant, manager_name='again')
-        register(User, manager_name='again')
-        self.assertTrue(hasattr(Restaurant, 'updates'))
-        self.assertFalse(hasattr(Restaurant, 'again'))
-        self.assertTrue(hasattr(User, 'histories'))
-        self.assertFalse(hasattr(User, 'again'))
+        with self.assertRaises(exceptions.MultipleRegistrationsError):
+            register(Restaurant, manager_name='again')
 
     def test_register_custome_records(self):
         self.assertEqual(len(Voter.history.all()), 0)