import functools
from importlib import import_module
from django.core.exceptions import ViewDoesNotExist
from django.utils.module_loading import module_has_submodule
@functools.lru_cache(maxsize=None)
def get_callable(lookup_view):
"""
Return a callable corresponding to lookup_view.
* If lookup_view is already a callable, return it.
* If lookup_view is a string import path that can be resolved to a callable,
import that callable and return it, otherwise raise an exception
(ImportError or ViewDoesNotExist).
"""
if callable(lookup_view):
return lookup_view
if not isinstance(lookup_view, str):
raise ViewDoesNotExist("'%s' is not a callable or a dot-notation path" % lookup_view)
mod_name, func_name = get_mod_func(lookup_view)
if not func_name: # No '.' in lookup_view
raise ImportError("Could not import '%s'. The path must be fully qualified." % lookup_view)
try:
mod = import_module(mod_name)
except ImportError:
parentmod, submod = get_mod_func(mod_name)
if submod and not module_has_submodule(import_module(parentmod), submod):
raise ViewDoesNotExist(
"Could not import '%s'. Parent module %s does not exist." %
(lookup_view, mod_name)
)
else:
raise
else:
try:
view_func = getattr(mod, func_name)
except AttributeError:
raise ViewDoesNotExist(
"Could not import '%s'. View does not exist in module %s." %
(lookup_view, mod_name)
)
else:
if not callable(view_func):
raise ViewDoesNotExist(
"Could not import '%s.%s'. View is not callable." %
(mod_name, func_name)
)
return view_func
def get_mod_func(callback):
# Convert 'django.views.news.stories.story_detail' to
# ['django.views.news.stories', 'story_detail']
try:
dot = callback.rindex('.')
except ValueError:
return callback, ''
return callback[:dot], callback[dot + 1:]