Source code for django.utils.module_loading

from __future__ import absolute_import  # Avoid importing `importlib` from this package.

import copy
import imp
from importlib import import_module
import os
import sys
import warnings

from django.core.exceptions import ImproperlyConfigured
from django.utils import six
from django.utils.deprecation import RemovedInDjango19Warning

[docs]def import_string(dotted_path): """ Import a dotted module path and return the attribute/class designated by the last name in the path. Raise ImportError if the import failed. """ try: module_path, class_name = dotted_path.rsplit('.', 1) except ValueError: msg = "%s doesn't look like a module path" % dotted_path six.reraise(ImportError, ImportError(msg), sys.exc_info()[2]) module = import_module(module_path) try: return getattr(module, class_name) except AttributeError: msg = 'Module "%s" does not define a "%s" attribute/class' % ( dotted_path, class_name) six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])
[docs]def import_by_path(dotted_path, error_prefix=''): """ Import a dotted module path and return the attribute/class designated by the last name in the path. Raise ImproperlyConfigured if something goes wrong. """ warnings.warn( 'import_by_path() has been deprecated. Use import_string() instead.', RemovedInDjango19Warning, stacklevel=2) try: attr = import_string(dotted_path) except ImportError as e: msg = '%sError importing module %s: "%s"' % ( error_prefix, dotted_path, e) six.reraise(ImproperlyConfigured, ImproperlyConfigured(msg), sys.exc_info()[2]) return attr
def autodiscover_modules(*args, **kwargs): """ Auto-discover INSTALLED_APPS modules and fail silently when not present. This forces an import on them to register any admin bits they may want. You may provide a register_to keyword parameter as a way to access a registry. This register_to object must have a _registry instance variable to access it. """ from django.apps import apps register_to = kwargs.get('register_to') for app_config in apps.get_app_configs(): # Attempt to import the app's module. try: if register_to: before_import_registry = copy.copy(register_to._registry) for module_to_search in args: import_module('%s.%s' % (, module_to_search)) except: # Reset the model registry to the state before the last import as # this import will have to reoccur on the next request and this # could raise NotRegistered and AlreadyRegistered exceptions # (see #8245). if register_to: register_to._registry = before_import_registry # Decide whether to bubble up this error. If the app just # doesn't have an admin module, we can ignore the error # attempting to import it, otherwise we want it to bubble up. if module_has_submodule(app_config.module, module_to_search): raise def module_has_submodule(package, module_name): """See if 'module' is in 'package'.""" name = ".".join([package.__name__, module_name]) try: # None indicates a cached miss; see mark_miss() in Python/import.c. return sys.modules[name] is not None except KeyError: pass try: package_path = package.__path__ # No __path__, then not a package. except AttributeError: # Since the remainder of this function assumes that we're dealing with # a package (module with a __path__), so if it's not, then bail here. return False for finder in sys.meta_path: if finder.find_module(name, package_path): return True for entry in package_path: try: # Try the cached finder. finder = sys.path_importer_cache[entry] if finder is None: # Implicit import machinery should be used. try: file_, _, _ = imp.find_module(module_name, [entry]) if file_: file_.close() return True except ImportError: continue # Else see if the finder knows of a loader. elif finder.find_module(name): return True else: continue except KeyError: # No cached finder, so try and make one. for hook in sys.path_hooks: try: finder = hook(entry) # XXX Could cache in sys.path_importer_cache if finder.find_module(name): return True else: # Once a finder is found, stop the search. break except ImportError: # Continue the search for a finder. continue else: # No finder found. # Try the implicit import machinery if searching a directory. if os.path.isdir(entry): try: file_, _, _ = imp.find_module(module_name, [entry]) if file_: file_.close() return True except ImportError: pass # XXX Could insert None or NullImporter else: # Exhausted the search, so the module cannot be found. return False