Source code for django.apps.config

import inspect
import os
import warnings
from importlib import import_module

from django.core.exceptions import ImproperlyConfigured
from django.utils.deprecation import RemovedInDjango41Warning
from django.utils.functional import cached_property
from django.utils.module_loading import import_string, module_has_submodule


[docs]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'. = app_name # Root module for the application e.g. <module 'django.contrib.admin' # from 'django/contrib/admin/'>. 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] if not self.label.isidentifier(): raise ImproperlyConfigured( "The app label '%s' is not a valid Python identifier." % self.label ) # 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/'>. 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) @cached_property def default_auto_field(self): from django.conf import settings return settings.DEFAULT_AUTO_FIELD @property def _is_default_auto_field_overridden(self): return self.__class__.default_auto_field is not AppConfig.default_auto_field 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. """ # create() eventually returns app_config_class(app_name, app_module). app_config_class = None app_config_name = None app_name = None app_module = None # If import_module succeeds, entry points to the app module. try: app_module = import_module(entry) except Exception: pass else: # If app_module has an apps submodule that defines a single # AppConfig subclass, use it automatically. # To prevent this, an AppConfig subclass can declare a class # variable default = False. # If the apps module defines more than one AppConfig subclass, # the default one can declare default = True. if module_has_submodule(app_module, APPS_MODULE_NAME): mod_path = '%s.%s' % (entry, APPS_MODULE_NAME) mod = import_module(mod_path) # Check if there's exactly one AppConfig candidate, # excluding those that explicitly define default = False. app_configs = [ (name, candidate) for name, candidate in inspect.getmembers(mod, inspect.isclass) if ( issubclass(candidate, cls) and candidate is not cls and getattr(candidate, 'default', True) ) ] if len(app_configs) == 1: app_config_class = app_configs[0][1] app_config_name = '%s.%s' % (mod_path, app_configs[0][0]) else: # Check if there's exactly one AppConfig subclass, # among those that explicitly define default = True. app_configs = [ (name, candidate) for name, candidate in app_configs if getattr(candidate, 'default', False) ] if len(app_configs) > 1: candidates = [repr(name) for name, _ in app_configs] raise RuntimeError( '%r declares more than one default AppConfig: ' '%s.' % (mod_path, ', '.join(candidates)) ) elif len(app_configs) == 1: app_config_class = app_configs[0][1] app_config_name = '%s.%s' % (mod_path, app_configs[0][0]) # If app_module specifies a default_app_config, follow the link. # default_app_config is deprecated, but still takes over the # automatic detection for backwards compatibility during the # deprecation period. try: new_entry = app_module.default_app_config except AttributeError: # Use the default app config class if we didn't find anything. if app_config_class is None: app_config_class = cls app_name = entry else: message = ( '%r defines default_app_config = %r. ' % (entry, new_entry) ) if new_entry == app_config_name: message += ( 'Django now detects this configuration automatically. ' 'You can remove default_app_config.' ) else: message += ( "However, Django's automatic detection %s. You should " "move the default config class to the apps submodule " "of your application and, if this module defines " "several config classes, mark the default one with " "default = True." % ( "picked another configuration, %r" % app_config_name if app_config_name else "did not find this configuration" ) ) warnings.warn(message, RemovedInDjango41Warning, stacklevel=2) entry = new_entry app_config_class = None # If import_string succeeds, entry is an app config class. if app_config_class is None: try: app_config_class = import_string(entry) except Exception: pass # If both import_module and import_string failed, it means that entry # doesn't have a valid value. if app_module is None and app_config_class is None: # If the last component of entry starts with an uppercase letter, # then it was likely intended to be an app config class; if not, # an app module. Provide a nice error message in both cases. mod_path, _, cls_name = entry.rpartition('.') if mod_path and cls_name[0].isupper(): # We could simply re-trigger the string import exception, but # we're going the extra mile and providing a better error # message for typos in INSTALLED_APPS. # This may raise ImportError, which is the best exception # possible if the module at mod_path cannot be imported. mod = import_module(mod_path) candidates = [ repr(name) for name, candidate in inspect.getmembers(mod, inspect.isclass) if issubclass(candidate, cls) and candidate is not cls ] msg = "Module '%s' does not contain a '%s' class." % (mod_path, cls_name) if candidates: msg += ' Choices are: %s.' % ', '.join(candidates) raise ImportError(msg) else: # Re-trigger the module import exception. import_module(entry) # Check for obvious errors. (This check prevents duck typing, but # it could be removed if it became a problem in practice.) if not issubclass(app_config_class, 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. if app_name is None: try: app_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 '' is correct." % ( app_name, app_config_class.__module__, app_config_class.__qualname__, ) ) # Entry is a path to an app config class. return app_config_class(app_name, app_module)
[docs] 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))
[docs] 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' % (, 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. """
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