django 2.1错误： Specifying a namespace in include() without providing an app_name is not supported
django 2.1错误： Specifying a namespace in include() without providing an app_name is not supported
错误信息:
File "I:\xx\urls.py", line 22, in
url('', include('system.urls', namespace='system-urls')),
File "I:\xx\venv\lib\site-packages\django\urls\conf.py", line 39, in include
'Specifying a namespace in include() without providing an app_name '
django.core.exceptions.ImproperlyConfigured: Specifying a namespace in include()
without providing an app_name is not supported. Set the app_name attribute in the
included module, or pass a 2-tuple containing the list of patterns and app_name instead.
错误的代码：
urlpatterns = [
url('', include('apps.urls', namespace='apps-urls')),
]
背景：
django == 2.1
错误意思为：
django.core.exceptions.ImproperlyConfigured：不支持在include（）中指定名称空间而不提供app_name。 在包含的模块中设置app_name属性，或者传递包含模式列表和app_name的2元组。
源码文件：
def include(arg, namespace=None):
app_name = None
if isinstance(arg, tuple):
# Callable returning a namespace hint.
try:
urlconf_module, app_name = arg
except ValueError:
if namespace:
raise ImproperlyConfigured(
'Cannot override the namespace for a dynamic module that '
'provides a namespace.'
)
raise ImproperlyConfigured(
'Passing a %d-tuple to include() is not supported. Pass a '
'2-tuple containing the list of patterns and app_name, and '
'provide the namespace argument to include() instead.' % len(arg)
)
else:
# No namespace hint - use manually provided namespace.
urlconf_module = arg
if isinstance(urlconf_module, str):
urlconf_module = import_module(urlconf_module)
patterns = getattr(urlconf_module, 'urlpatterns', urlconf_module)
app_name = getattr(urlconf_module, 'app_name', app_name)
if namespace and not app_name:
raise ImproperlyConfigured(
'Specifying a namespace in include() without providing an app_name '
'is not supported. Set the app_name attribute in the included '
'module, or pass a 2-tuple containing the list of patterns and '
'app_name instead.',
)
namespace = namespace or app_name
# Make sure the patterns can be iterated through (without this, some
# testcases will break).
if isinstance(patterns, (list, tuple)):
for url_pattern in patterns:
pattern = getattr(url_pattern, 'pattern', None)
if isinstance(pattern, LocalePrefixPattern):
raise ImproperlyConfigured(
'Using i18n_patterns in an included URLconf is not allowed.'
)
return (urlconf_module, app_name, namespace)
从上述源码可以看到，include需要两个参数，arg和namespace, 当namespace不为空时，arg参数必须是一个2元组，除了urlpatterns不能为空之外，app_name也必须填写。
解决办法：
urlpatterns = [
url('', include(('apps.urls', 'apps'), namespace='apps-urls')),
]