import copy
import os
from importlib import import_module
from importlib.util import find_spec as importlib_find
[文档]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 as err:
raise ImportError("%s doesn't look like a module path" % dotted_path) from err
module = import_module(module_path)
try:
return getattr(module, class_name)
except AttributeError as err:
raise ImportError('Module "%s" does not define a "%s" attribute/class' % (
module_path, class_name)
) from err
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():
for module_to_search in args:
# Attempt to import the app's module.
try:
if register_to:
before_import_registry = copy.copy(register_to._registry)
import_module('%s.%s' % (app_config.name, module_to_search))
except Exception:
# Reset the 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 the module in question, 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'."""
try:
package_name = package.__name__
package_path = package.__path__
except AttributeError:
# package isn't a package.
return False
full_module_name = package_name + '.' + module_name
try:
return importlib_find(full_module_name, package_path) is not None
except (ImportError, AttributeError):
# When module_name is an invalid dotted path, Python raises ImportError
# (or ModuleNotFoundError in Python 3.6+). AttributeError may be raised
# if the penultimate part of the path is not a package.
# (https://bugs.python.org/issue30436)
return False
def module_dir(module):
"""
Find the name of the directory that contains a module, if possible.
Raise ValueError otherwise, e.g. for namespace packages that are split
over several directories.
"""
# Convert to list because _NamespacePath does not support indexing on 3.3.
paths = list(getattr(module, '__path__', []))
if len(paths) == 1:
return paths[0]
else:
filename = getattr(module, '__file__', None)
if filename is not None:
return os.path.dirname(filename)
raise ValueError("Cannot determine directory containing %s" % module)
