From aff57793b46e108c6e48d5ce3b889bf90b513df9 Mon Sep 17 00:00:00 2001 From: Aymeric Augustin Date: Fri, 27 Dec 2013 23:03:03 +0100 Subject: [PATCH] Simplified the implementation of register_model. register_model is called exactly once in the entire Django code base, at the bottom of ModelBase.__new__: new_class._meta.apps.register_model(new_class._meta.app_label, new_class) ModelBase.__new__ exits prematurely 120 lines earlier (sigh) if a model with the same name is already registered: if new_class._meta.apps.get_registered_model(new_class._meta.app_label, name): return (This isn't the exact code, but it's equivalent.) apps.register_model and apps.get_registered_model are essentially a setter and a getter for apps.all_models, and apps.register_model is the only setter. As a consequence, new_class._meta.apps.all_models cannot change in-between. Considering that name == new_class.__name__, we can conclude that register_model(app_label, model) is always called with such arguments that get_registered_model(app_label, model.__name__) returns None. Considering that model._meta.model_name == model.__name__.lower(), and looking at the implementation of register_model and get_registered_model, this proves that self.all_models[app_label] doesn't contain model._meta.model_name in register_model, allowing us to simplify the implementation. --- django/apps/registry.py | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-) diff --git a/django/apps/registry.py b/django/apps/registry.py index 8a25bad281b..42affbbc13d 100644 --- a/django/apps/registry.py +++ b/django/apps/registry.py @@ -261,19 +261,13 @@ class Apps(object): # perform imports because of the risk of import loops. It mustn't # call get_app_config(). model_name = model._meta.model_name - models = self.all_models[app_label] - if model_name in models: - # 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[models[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 - models[model_name] = model + app_models = self.all_models[app_label] + # Defensive check for extra safety. + if model_name in app_models: + raise RuntimeError( + "Conflicting '%s' models in application '%s': %s and %s." % + (model_name, app_label, app_models[model_name], model)) + app_models[model_name] = model self.get_models.cache_clear() def has_app(self, app_name):