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205 lines
8.0 KiB
Python
205 lines
8.0 KiB
Python
import os
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from importlib import import_module
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from django.core.exceptions import AppRegistryNotReady, ImproperlyConfigured
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from django.utils._os import upath
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from django.utils.module_loading import module_has_submodule
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MODELS_MODULE_NAME = 'models'
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class AppConfig(object):
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"""
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Class representing a Django application and its configuration.
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"""
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def __init__(self, app_name, app_module):
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# Full Python path to the application eg. 'django.contrib.admin'.
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self.name = app_name
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# Root module for the application eg. <module 'django.contrib.admin'
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# from 'django/contrib/admin/__init__.pyc'>.
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self.module = app_module
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# The following attributes could be defined at the class level in a
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# subclass, hence the test-and-set pattern.
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# Last component of the Python path to the application eg. 'admin'.
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# This value must be unique across a Django project.
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if not hasattr(self, 'label'):
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self.label = app_name.rpartition(".")[2]
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# Human-readable name for the application eg. "Admin".
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if not hasattr(self, 'verbose_name'):
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self.verbose_name = self.label.title()
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# Filesystem path to the application directory eg.
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# u'/usr/lib/python2.7/dist-packages/django/contrib/admin'. Unicode on
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# Python 2 and a str on Python 3.
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if not hasattr(self, 'path'):
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self.path = self._path_from_module(app_module)
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# Module containing models eg. <module 'django.contrib.admin.models'
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# from 'django/contrib/admin/models.pyc'>. Set by import_models().
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# None if the application doesn't have a models module.
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self.models_module = None
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# Mapping of lower case model names to model classes. Initially set to
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# None to prevent accidental access before import_models() runs.
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self.models = None
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def __repr__(self):
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return '<%s: %s>' % (self.__class__.__name__, self.label)
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def _path_from_module(self, module):
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"""Attempt to determine app's filesystem path from its module."""
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# See #21874 for extended discussion of the behavior of this method in
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# various cases.
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# Convert paths to list because Python 3's _NamespacePath does not
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# support indexing.
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paths = list(getattr(module, '__path__', []))
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if len(paths) != 1:
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filename = getattr(module, '__file__', None)
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if filename is not None:
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paths = [os.path.dirname(filename)]
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else:
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# For unknown reasons, sometimes the list returned by __path__
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# contains duplicates that must be removed (#25246).
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paths = list(set(paths))
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if len(paths) > 1:
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raise ImproperlyConfigured(
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"The app module %r has multiple filesystem locations (%r); "
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"you must configure this app with an AppConfig subclass "
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"with a 'path' class attribute." % (module, paths))
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elif not paths:
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raise ImproperlyConfigured(
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"The app module %r has no filesystem location, "
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"you must configure this app with an AppConfig subclass "
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"with a 'path' class attribute." % (module,))
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return upath(paths[0])
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@classmethod
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def create(cls, entry):
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"""
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Factory that creates an app config from an entry in INSTALLED_APPS.
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"""
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try:
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# If import_module succeeds, entry is a path to an app module,
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# which may specify an app config class with default_app_config.
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# Otherwise, entry is a path to an app config class or an error.
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module = import_module(entry)
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except ImportError:
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# Track that importing as an app module failed. If importing as an
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# app config class fails too, we'll trigger the ImportError again.
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module = None
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mod_path, _, cls_name = entry.rpartition('.')
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# Raise the original exception when entry cannot be a path to an
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# app config class.
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if not mod_path:
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raise
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else:
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try:
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# If this works, the app module specifies an app config class.
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entry = module.default_app_config
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except AttributeError:
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# Otherwise, it simply uses the default app config class.
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return cls(entry, module)
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else:
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mod_path, _, cls_name = entry.rpartition('.')
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# If we're reaching this point, we must attempt to load the app config
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# class located at <mod_path>.<cls_name>
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mod = import_module(mod_path)
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try:
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cls = getattr(mod, cls_name)
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except AttributeError:
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if module is None:
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# If importing as an app module failed, that error probably
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# contains the most informative traceback. Trigger it again.
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import_module(entry)
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else:
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raise
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# Check for obvious errors. (This check prevents duck typing, but
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# it could be removed if it became a problem in practice.)
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if not issubclass(cls, AppConfig):
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raise ImproperlyConfigured(
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"'%s' isn't a subclass of AppConfig." % entry)
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# Obtain app name here rather than in AppClass.__init__ to keep
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# all error checking for entries in INSTALLED_APPS in one place.
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try:
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app_name = cls.name
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except AttributeError:
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raise ImproperlyConfigured(
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"'%s' must supply a name attribute." % entry)
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# Ensure app_name points to a valid module.
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app_module = import_module(app_name)
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# Entry is a path to an app config class.
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return cls(app_name, app_module)
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def check_models_ready(self):
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"""
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Raises an exception if models haven't been imported yet.
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"""
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if self.models is None:
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raise AppRegistryNotReady(
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"Models for app '%s' haven't been imported yet." % self.label)
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def get_model(self, model_name):
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"""
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Returns the model with the given case-insensitive model_name.
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Raises LookupError if no model exists with this name.
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"""
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self.check_models_ready()
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try:
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return self.models[model_name.lower()]
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except KeyError:
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raise LookupError(
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"App '%s' doesn't have a '%s' model." % (self.label, model_name))
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def get_models(self, include_auto_created=False, include_swapped=False):
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"""
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Returns an iterable of models.
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By default, the following models aren't included:
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- auto-created models for many-to-many relations without
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an explicit intermediate table,
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- models created to satisfy deferred attribute queries,
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- models that have been swapped out.
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Set the corresponding keyword argument to True to include such models.
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Keyword arguments aren't documented; they're a private API.
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"""
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self.check_models_ready()
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for model in self.models.values():
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if model._meta.auto_created and not include_auto_created:
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continue
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if model._meta.swapped and not include_swapped:
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continue
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yield model
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def import_models(self, all_models):
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# Dictionary of models for this app, primarily maintained in the
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# 'all_models' attribute of the Apps this AppConfig is attached to.
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# Injected as a parameter because it gets populated when models are
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# imported, which might happen before populate() imports models.
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self.models = all_models
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if module_has_submodule(self.module, MODELS_MODULE_NAME):
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models_module_name = '%s.%s' % (self.name, MODELS_MODULE_NAME)
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self.models_module = import_module(models_module_name)
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def ready(self):
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"""
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Override this method in subclasses to run code when Django starts.
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"""
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