Set app label via instantiation of historical records (#486)

* GH Issue 485 - add ability to override default app_label in generated
history model

* GH Issue 485 - add test model to test override default app_label in
generated history model

* GH Issue 485 - add test for ability to override default app_label in
generated history model

* GH Issue 485 - document ability to override default app_label in
generated history model

* Add name to list

* Document enhancement

Author: uhurusurfa

AUTHORS.rst

@@ -73,6 +73,7 @@ Authors
 - Jim Gomez
 - Hanyin Zhang
 - James Muranga (@jamesmura)
+- Christopher Broderick (@uhurusurfa)
 
 Background
 ==========

CHANGES.rst

@@ -3,6 +3,7 @@ Changes
 
 Unreleased
 ----------
+- Add `app` parameter to the constructor of `HistoricalRecords` (gh-486)
 - Add `custom_model_name` parameter to the constructor of `HistoricalRecords` (gh-451)
 - Fix header on history pages when custom site_header is used (gh-448)
 - Modify `pre_create_historircal_record` to pass `history_instance` for ease of customization (gh-421)

docs/advanced.rst

@@ -541,3 +541,24 @@ To connect the signals to your callbacks, you can use the @receiver decorator:
     @receiver(post_create_historical_record)
     def post_create_historical_record_callback(sender, **kwargs):
         print("Sent after saving historical record")
+
+History Model In Different App
+------------------------------
+
+By default the app_label for the history model is the same as the base model.
+In some circumstances you may want to have the history models belong in a different app.
+This will support creating history models in a different database to the base model using
+database routing functionality based on app_label.
+To configure history models in a different app, add this to the HistoricalRecords instantiation
+or the record invocation: ``app="SomeAppName"``.
+
+.. code-block:: python
+
+    class Poll(models.Model):
+        question = models.CharField(max_length=200)
+        history = HistoricalRecords(app="SomeAppName")
+
+    class Opinion(models.Model):
+        opinion = models.CharField(max_length=2000)
+
+    register(Opinion, app="SomeAppName")

simple_history/models.py

@@ -50,6 +50,7 @@ def __init__(
         get_user=default_get_user,
         cascade_delete_history=False,
         custom_model_name=None,
+        app=None,
     ):
         self.user_set_verbose_name = verbose_name
         self.user_related_name = user_related_name
@@ -61,6 +62,7 @@ def __init__(
         self.get_user = get_user
         self.cascade_delete_history = cascade_delete_history
         self.custom_model_name = custom_model_name
+        self.app = app
         if excluded_fields is None:
             excluded_fields = []
         self.excluded_fields = excluded_fields
@@ -340,6 +342,8 @@ def get_meta_options(self, model):
         else:
             name = format_lazy("historical {}", smart_text(model._meta.verbose_name))
         meta_fields["verbose_name"] = name
+        if self.app:
+            meta_fields["app_label"] = self.app
         return meta_fields
 
     def post_save(self, instance, created, **kwargs):

simple_history/registry_tests/tests.py

@@ -28,6 +28,7 @@
     UUIDRegisterModel,
     Voter,
     ModelWithCustomAttrForeignKey,
+    ModelWithHistoryInDifferentApp,
 )
 
 get_model = apps.get_model
@@ -211,3 +212,11 @@ def test_migrate_command(self):
         management.call_command(
             "migrate", "migration_test_app", fake=True, stdout=StringIO()
         )
+
+
+class TestModelWithHistoryInDifferentApp(TestCase):
+    """ https://github.com/treyhunner/django-simple-history/issues/485 """
+
+    def test__different_app(self):
+        appLabel = ModelWithHistoryInDifferentApp.history.model._meta.app_label
+        self.assertEqual(appLabel, "external")

simple_history/tests/models.py

@@ -356,6 +356,11 @@ class ContactRegister(models.Model):
 register(ContactRegister, table_name="contacts_register_history")
 
 
+class ModelWithHistoryInDifferentApp(models.Model):
+    name = models.CharField(max_length=30)
+    history = HistoricalRecords(app="external")
+
+
 ###############################################################################
 #
 # Inheritance examples