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stbi/Lib/site-packages/django/apps/config.py

+import os
+from importlib import import_module
+
+from django.core.exceptions import ImproperlyConfigured
+from django.utils.module_loading import module_has_submodule
+
+MODELS_MODULE_NAME = 'models'
+
+
+class AppConfig:
+    """Class representing a Django application and its configuration."""
+
+    def __init__(self, app_name, app_module):
+        # Full Python path to the application e.g. 'django.contrib.admin'.
+        self.name = app_name
+
+        # Root module for the application e.g. <module 'django.contrib.admin'
+        # from 'django/contrib/admin/__init__.py'>.
+        self.module = app_module
+
+        # Reference to the Apps registry that holds this AppConfig. Set by the
+        # registry when it registers the AppConfig instance.
+        self.apps = None
+
+        # 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 e.g. 'admin'.
+        # This value must be unique across a Django project.
+        if not hasattr(self, 'label'):
+            self.label = app_name.rpartition(".")[2]
+
+        # Human-readable name for the application e.g. "Admin".
+        if not hasattr(self, 'verbose_name'):
+            self.verbose_name = self.label.title()
+
+        # Filesystem path to the application directory e.g.
+        # '/path/to/django/contrib/admin'.
+        if not hasattr(self, 'path'):
+            self.path = self._path_from_module(app_module)
+
+        # Module containing models e.g. <module 'django.contrib.admin.models'
+        # from 'django/contrib/admin/models.py'>. Set by import_models().
+        # None if the application doesn't have a models module.
+        self.models_module = None
+
+        # Mapping of lowercase 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's _NamespacePath doesn't 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 paths[0]
+
+    @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, check if the module
+                # contains any valid AppConfigs and show them as choices.
+                # Otherwise, that error probably contains the most informative
+                # traceback, so trigger it again.
+                candidates = sorted(
+                    repr(name) for name, candidate in mod.__dict__.items()
+                    if isinstance(candidate, type) and
+                    issubclass(candidate, AppConfig) and
+                    candidate is not AppConfig
+                )
+                if candidates:
+                    raise ImproperlyConfigured(
+                        "'%s' does not contain a class '%s'. Choices are: %s."
+                        % (mod_path, cls_name, ', '.join(candidates))
+                    )
+                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.
+        try:
+            app_module = import_module(app_name)
+        except ImportError:
+            raise ImproperlyConfigured(
+                "Cannot import '%s'. Check that '%s.%s.name' is correct." % (
+                    app_name, mod_path, cls_name,
+                )
+            )
+
+        # Entry is a path to an app config class.
+        return cls(app_name, app_module)
+
+    def get_model(self, model_name, require_ready=True):
+        """
+        Return the model with the given case-insensitive model_name.
+
+        Raise LookupError if no model exists with this name.
+        """
+        if require_ready:
+            self.apps.check_models_ready()
+        else:
+            self.apps.check_apps_ready()
+        try:
+            return self.models[model_name.lower()]
+        except KeyError:
+            raise LookupError(
+                "App '%s' doesn't have a '%s' model." % (self.label, model_name))
+
+    def get_models(self, include_auto_created=False, include_swapped=False):
+        """
+        Return 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 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.apps.check_models_ready()
+        for model in self.models.values():
+            if model._meta.auto_created and not include_auto_created:
+                continue
+            if model._meta.swapped and not include_swapped:
+                continue
+            yield model
+
+    def import_models(self):
+        # Dictionary of models for this app, primarily maintained in the
+        # 'all_models' attribute of the Apps this AppConfig is attached to.
+        self.models = self.apps.all_models[self.label]
+
+        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)
+
+    def ready(self):
+        """
+        Override this method in subclasses to run code when Django starts.
+        """