Simplified register_models.

Since it's never called with more than one model at a time the current
signature is needlessly complicated.

django/apps/base.py

@@ -26,7 +26,7 @@ class AppConfig(object):
         self.models_module = models_module
 
         # Mapping of lower case model names to model classes.
-        # Populated by AppCache.register_models().
+        # Populated by calls to AppCache.register_model().
         self.models = OrderedDict()
 
         # Whether the app is in INSTALLED_APPS or was automatically created

django/apps/cache.py

@@ -302,32 +302,27 @@ class BaseAppCache(object):
         except KeyError:
             return None
 
-    def register_models(self, app_label, *models):
-        """
-        Register a set of models as belonging to an app.
-        """
-        if models:
-            try:
-                app_config = self.app_configs[app_label]
-            except KeyError:
-                app_config = AppConfig._stub(app_label)
-                self.app_configs[app_label] = app_config
-        for model in models:
-            # Add the model to the app_config's models dictionary.
-            model_name = model._meta.model_name
-            model_dict = app_config.models
-            if model_name in model_dict:
-                # The same model may be imported via different paths (e.g.
-                # appname.models and project.appname.models). We use the source
-                # filename as a means to detect identity.
-                fname1 = os.path.abspath(upath(sys.modules[model.__module__].__file__))
-                fname2 = os.path.abspath(upath(sys.modules[model_dict[model_name].__module__].__file__))
-                # Since the filename extension could be .py the first time and
-                # .pyc or .pyo the second time, ignore the extension when
-                # comparing.
-                if os.path.splitext(fname1)[0] == os.path.splitext(fname2)[0]:
-                    continue
-            model_dict[model_name] = model
+    def register_model(self, app_label, model):
+        try:
+            app_config = self.app_configs[app_label]
+        except KeyError:
+            app_config = AppConfig._stub(app_label)
+            self.app_configs[app_label] = app_config
+        # Add the model to the app_config's models dictionary.
+        model_name = model._meta.model_name
+        model_dict = app_config.models
+        if model_name in model_dict:
+            # The same model may be imported via different paths (e.g.
+            # appname.models and project.appname.models). We use the source
+            # filename as a means to detect identity.
+            fname1 = os.path.abspath(upath(sys.modules[model.__module__].__file__))
+            fname2 = os.path.abspath(upath(sys.modules[model_dict[model_name].__module__].__file__))
+            # Since the filename extension could be .py the first time and
+            # .pyc or .pyo the second time, ignore the extension when
+            # comparing.
+            if os.path.splitext(fname1)[0] == os.path.splitext(fname2)[0]:
+                return
+        model_dict[model_name] = model
         self._get_models_cache.clear()
 
     def set_available_apps(self, available):
@@ -383,6 +378,16 @@ class BaseAppCache(object):
             app_paths.append(self._get_app_path(app))
         return app_paths
 
+    def register_models(self, app_label, *models):
+        """
+        Register a set of models as belonging to an app.
+        """
+        warnings.warn(
+            "register_models(app_label, models) is deprecated.",
+            PendingDeprecationWarning, stacklevel=2)
+        for model in models:
+            self.register_model(app_label, model)
+
 
 class AppCache(BaseAppCache):
     """

django/db/models/base.py

@@ -274,7 +274,7 @@ class ModelBase(type):
 
         new_class._prepare()
 
-        new_class._meta.app_cache.register_models(new_class._meta.app_label, new_class)
+        new_class._meta.app_cache.register_model(new_class._meta.app_label, new_class)
         # Because of the way imports happen (recursively), we may or may not be
         # the first time this model tries to register with the framework. There
         # should only be one class for each model, so we always return the

tests/migrations/test_commands.py

@@ -151,7 +151,7 @@ class MakeMigrationsTests(MigrationTestBase):
 
     def test_files_content(self):
         self.assertTableNotExists("migrations_unicodemodel")
-        app_cache.register_models('migrations', UnicodeModel)
+        app_cache.register_model('migrations', UnicodeModel)
         with override_settings(MIGRATION_MODULES={"migrations": self.migration_pkg}):
             call_command("makemigrations", "migrations", verbosity=0)
 
@@ -187,7 +187,7 @@ class MakeMigrationsTests(MigrationTestBase):
 
     def test_failing_migration(self):
         #21280 - If a migration fails to serialize, it shouldn't generate an empty file.
-        app_cache.register_models('migrations', UnserializableModel)
+        app_cache.register_model('migrations', UnserializableModel)
 
         with six.assertRaisesRegex(self, ValueError, r'Cannot serialize'):
             with override_settings(MIGRATION_MODULES={"migrations": self.migration_pkg}):