Source code for django.apps.config
import os from importlib import import_module from django.core.exceptions import AppRegistryNotReady, ImproperlyConfigured from django.utils._os import upath from django.utils.module_loading import module_has_submodule MODELS_MODULE_NAME = 'models'[docs]class AppConfig(object): """ Class representing a Django application and its configuration. """ def __init__(self, app_name, app_module): # Full Python path to the application eg. 'django.contrib.admin'. self.name = app_name # Root module for the application eg. <module 'django.contrib.admin' # from 'django/contrib/admin/__init__.pyc'>. self.module = app_module # The following attributes could be defined at the class level in a # subclass, hence the test-and-set pattern. # Last component of the Python path to the application eg. 'admin'. # This value must be unique across a Django project. if not hasattr(self, 'label'): self.label = app_name.rpartition(".") # Human-readable name for the application eg. "Admin". if not hasattr(self, 'verbose_name'): self.verbose_name = self.label.title() # Filesystem path to the application directory eg. # u'/usr/lib/python2.7/dist-packages/django/contrib/admin'. Unicode on # Python 2 and a str on Python 3. if not hasattr(self, 'path'): self.path = self._path_from_module(app_module) # Module containing models eg. <module 'django.contrib.admin.models' # from 'django/contrib/admin/models.pyc'>. Set by import_models(). # None if the application doesn't have a models module. self.models_module = None # Mapping of lower case model names to model classes. Initially set to # None to prevent accidental access before import_models() runs. self.models = None def __repr__(self): return '<%s: %s>' % (self.__class__.__name__, self.label) def _path_from_module(self, module): """Attempt to determine app's filesystem path from its module.""" # See #21874 for extended discussion of the behavior of this method in # various cases. # Convert paths to list because Python 3's _NamespacePath does not # support indexing. paths = list(getattr(module, '__path__', )) if len(paths) != 1: filename = getattr(module, '__file__', None) if filename is not None: paths = [os.path.dirname(filename)] else: # For unknown reasons, sometimes the list returned by __path__ # contains duplicates that must be removed (#25246). paths = list(set(paths)) if len(paths) > 1: raise ImproperlyConfigured( "The app module %r has multiple filesystem locations (%r); " "you must configure this app with an AppConfig subclass " "with a 'path' class attribute." % (module, paths)) elif not paths: raise ImproperlyConfigured( "The app module %r has no filesystem location, " "you must configure this app with an AppConfig subclass " "with a 'path' class attribute." % (module,)) return upath(paths) @classmethod def create(cls, entry): """ Factory that creates an app config from an entry in INSTALLED_APPS. """ try: # If import_module succeeds, entry is a path to an app module, # which may specify an app config class with default_app_config. # Otherwise, entry is a path to an app config class or an error. module = import_module(entry) except ImportError: # Track that importing as an app module failed. If importing as an # app config class fails too, we'll trigger the ImportError again. module = None mod_path, _, cls_name = entry.rpartition('.') # Raise the original exception when entry cannot be a path to an # app config class. if not mod_path: raise else: try: # If this works, the app module specifies an app config class. entry = module.default_app_config except AttributeError: # Otherwise, it simply uses the default app config class. return cls(entry, module) else: mod_path, _, cls_name = entry.rpartition('.') # If we're reaching this point, we must attempt to load the app config # class located at <mod_path>.<cls_name> mod = import_module(mod_path) try: cls = getattr(mod, cls_name) except AttributeError: if module is None: # If importing as an app module failed, that error probably # contains the most informative traceback. Trigger it again. import_module(entry) else: raise # Check for obvious errors. (This check prevents duck typing, but # it could be removed if it became a problem in practice.) if not issubclass(cls, AppConfig): raise ImproperlyConfigured( "'%s' isn't a subclass of AppConfig." % entry) # Obtain app name here rather than in AppClass.__init__ to keep # all error checking for entries in INSTALLED_APPS in one place. try: app_name = cls.name except AttributeError: raise ImproperlyConfigured( "'%s' must supply a name attribute." % entry) # Ensure app_name points to a valid module. app_module = import_module(app_name) # Entry is a path to an app config class. return cls(app_name, app_module) def check_models_ready(self): """ Raises an exception if models haven't been imported yet. """ if self.models is None: raise AppRegistryNotReady( "Models for app '%s' haven't been imported yet." % self.label)[docs] def get_model(self, model_name): """ Returns the model with the given case-insensitive model_name. Raises LookupError if no model exists with this name. """ self.check_models_ready() try: return self.models[model_name.lower()] except KeyError: raise LookupError( "App '%s' doesn't have a '%s' model." % (self.label, model_name))[docs] def get_models(self, include_auto_created=False, include_deferred=False, include_swapped=False): """ Returns an iterable of models. By default, the following models aren't included: - auto-created models for many-to-many relations without an explicit intermediate table, - models created to satisfy deferred attribute queries, - models that have been swapped out. Set the corresponding keyword argument to True to include such models. Keyword arguments aren't documented; they're a private API. """ self.check_models_ready() for model in self.models.values(): if model._deferred and not include_deferred: continue if model._meta.auto_created and not include_auto_created: continue if model._meta.swapped and not include_swapped: continue yield modeldef import_models(self, all_models): # Dictionary of models for this app, primarily maintained in the # 'all_models' attribute of the Apps this AppConfig is attached to. # Injected as a parameter because it gets populated when models are # imported, which might happen before populate() imports models. self.models = all_models if module_has_submodule(self.module, MODELS_MODULE_NAME): models_module_name = '%s.%s' % (self.name, MODELS_MODULE_NAME) self.models_module = import_module(models_module_name)[docs] def ready(self): """ Override this method in subclasses to run code when Django starts. """