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This module converts requested URLs to callback view functions.
RegexURLResolver is the main class here. Its resolve() method takes a URL (as
a string) and returns a ResolverMatch object which provides access to all
attributes of the resolved URL match.
from __future__ import unicode_literals
import functools
import re
from importlib import import_module
from threading import local
from django.core.exceptions import ImproperlyConfigured, ViewDoesNotExist
from django.http import Http404
from django.utils import lru_cache, six
from django.utils.datastructures import MultiValueDict
from django.utils.encoding import force_str, force_text, iri_to_uri
from django.utils.functional import cached_property, lazy
from django.utils.http import RFC3986_SUBDELIMS, urlquote
from django.utils.module_loading import module_has_submodule
from django.utils.regex_helper import normalize
from django.utils.six.moves.urllib.parse import urlsplit, urlunsplit
from django.utils.translation import get_language, override
# SCRIPT_NAME prefixes for each thread are stored here. If there's no entry for
# the current thread (which is the only one we ever access), it is assumed to
# be empty.
_prefixes = local()
# Overridden URLconfs for each thread are stored here.
_urlconfs = local()
class ResolverMatch(object):
def __init__(self, func, args, kwargs, url_name=None, app_names=None, namespaces=None):
self.func = func
self.args = args
self.kwargs = kwargs
self.url_name = url_name
# If a URLRegexResolver doesn't have a namespace or app_name, it passes
# in an empty value.
self.app_names = [x for x in app_names if x] if app_names else []
self.app_name = ':'.join(self.app_names)
if namespaces:
self.namespaces = [x for x in namespaces if x]
self.namespaces = []
self.namespace = ':'.join(self.namespaces)
if not hasattr(func, '__name__'):
# A class-based view
self._func_path = '.'.join([func.__class__.__module__, func.__class__.__name__])
# A function-based view
self._func_path = '.'.join([func.__module__, func.__name__])
view_path = url_name or self._func_path
self.view_name = ':'.join(self.namespaces + [view_path])
def __getitem__(self, index):
return (self.func, self.args, self.kwargs)[index]
def __repr__(self):
return "ResolverMatch(func=%s, args=%s, kwargs=%s, url_name=%s, app_names=%s, namespaces=%s)" % (
self._func_path, self.args, self.kwargs, self.url_name, self.app_names, self.namespaces)
class Resolver404(Http404):
class NoReverseMatch(Exception):
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, six.string_types):
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)
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)
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)
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_resolver(urlconf=None):
if urlconf is None:
from django.conf import settings
urlconf = settings.ROOT_URLCONF
return RegexURLResolver(r'^/', urlconf)
def get_ns_resolver(ns_pattern, resolver):
# Build a namespaced resolver for the given parent URLconf pattern.
# This makes it possible to have captured parameters in the parent
# URLconf pattern.
ns_resolver = RegexURLResolver(ns_pattern, resolver.url_patterns)
return RegexURLResolver(r'^/', [ns_resolver])
def get_mod_func(callback):
# Converts '' to
# ['', 'story_detail']
dot = callback.rindex('.')
except ValueError:
return callback, ''
return callback[:dot], callback[dot + 1:]
class LocaleRegexProvider(object):
A mixin to provide a default regex property which can vary by active
def __init__(self, regex):
# regex is either a string representing a regular expression, or a
# translatable string (using ugettext_lazy) representing a regular
# expression.
self._regex = regex
self._regex_dict = {}
def regex(self):
Returns a compiled regular expression, depending upon the activated
language_code = get_language()
if language_code not in self._regex_dict:
if isinstance(self._regex, six.string_types):
regex = self._regex
regex = force_text(self._regex)
compiled_regex = re.compile(regex, re.UNICODE)
except re.error as e:
raise ImproperlyConfigured(
'"%s" is not a valid regular expression: %s' %
(regex, six.text_type(e)))
self._regex_dict[language_code] = compiled_regex
return self._regex_dict[language_code]
class RegexURLPattern(LocaleRegexProvider):
def __init__(self, regex, callback, default_args=None, name=None):
LocaleRegexProvider.__init__(self, regex)
self.callback = callback # the view
self.default_args = default_args or {} = name
def __repr__(self):
return force_str('<%s %s %s>' % (self.__class__.__name__,, self.regex.pattern))
def resolve(self, path):
match =
if match:
# If there are any named groups, use those as kwargs, ignoring
# non-named groups. Otherwise, pass all non-named arguments as
# positional arguments.
kwargs = match.groupdict()
if kwargs:
args = ()
args = match.groups()
# In both cases, pass any extra_kwargs as **kwargs.
return ResolverMatch(self.callback, args, kwargs,
def lookup_str(self):
A string that identifies the view (e.g. '' or
callback = self.callback
if isinstance(callback, functools.partial):
callback = callback.func
if not hasattr(callback, '__name__'):
return callback.__module__ + "." + callback.__class__.__name__
return callback.__module__ + "." + callback.__name__
class RegexURLResolver(LocaleRegexProvider):
def __init__(self, regex, urlconf_name, default_kwargs=None, app_name=None, namespace=None):
LocaleRegexProvider.__init__(self, regex)
# urlconf_name is the dotted Python path to the module defining
# urlpatterns. It may also be an object with an urlpatterns attribute
# or urlpatterns itself.
self.urlconf_name = urlconf_name
self.callback = None
self.default_kwargs = default_kwargs or {}
self.namespace = namespace
self.app_name = app_name
self._reverse_dict = {}
self._namespace_dict = {}
self._app_dict = {}
# set of dotted paths to all functions and classes that are used in
# urlpatterns
self._callback_strs = set()
self._populated = False
def __repr__(self):
if isinstance(self.urlconf_name, list) and len(self.urlconf_name):
# Don't bother to output the whole list, it can be huge
urlconf_repr = '<%s list>' % self.urlconf_name[0].__class__.__name__
urlconf_repr = repr(self.urlconf_name)
return str('<%s %s (%s:%s) %s>') % (
self.__class__.__name__, urlconf_repr, self.app_name,
self.namespace, self.regex.pattern)
def _populate(self):
lookups = MultiValueDict()
namespaces = {}
apps = {}
language_code = get_language()
for pattern in reversed(self.url_patterns):
if isinstance(pattern, RegexURLPattern):
p_pattern = pattern.regex.pattern
if p_pattern.startswith('^'):
p_pattern = p_pattern[1:]
if isinstance(pattern, RegexURLResolver):
if pattern.namespace:
namespaces[pattern.namespace] = (p_pattern, pattern)
if pattern.app_name:
apps.setdefault(pattern.app_name, []).append(pattern.namespace)
parent_pat = pattern.regex.pattern
for name in pattern.reverse_dict:
for matches, pat, defaults in pattern.reverse_dict.getlist(name):
new_matches = normalize(parent_pat + pat)
p_pattern + pat,
dict(defaults, **pattern.default_kwargs),
for namespace, (prefix, sub_pattern) in pattern.namespace_dict.items():
namespaces[namespace] = (p_pattern + prefix, sub_pattern)
for app_name, namespace_list in pattern.app_dict.items():
apps.setdefault(app_name, []).extend(namespace_list)
bits = normalize(p_pattern)
lookups.appendlist(pattern.callback, (bits, p_pattern, pattern.default_args))
if is not None:
lookups.appendlist(, (bits, p_pattern, pattern.default_args))
self._reverse_dict[language_code] = lookups
self._namespace_dict[language_code] = namespaces
self._app_dict[language_code] = apps
self._populated = True
def reverse_dict(self):
language_code = get_language()
if language_code not in self._reverse_dict:
return self._reverse_dict[language_code]
def namespace_dict(self):
language_code = get_language()
if language_code not in self._namespace_dict:
return self._namespace_dict[language_code]
def app_dict(self):
language_code = get_language()
if language_code not in self._app_dict:
return self._app_dict[language_code]
def _is_callback(self, name):
if not self._populated:
return name in self._callback_strs
def resolve(self, path):
path = force_text(path) # path may be a reverse_lazy object
tried = []
match =
if match:
new_path = path[match.end():]
for pattern in self.url_patterns:
sub_match = pattern.resolve(new_path)
except Resolver404 as e:
sub_tried = e.args[0].get('tried')
if sub_tried is not None:
tried.extend([pattern] + t for t in sub_tried)
if sub_match:
# Merge captured arguments in match with submatch
sub_match_dict = dict(match.groupdict(), **self.default_kwargs)
# If there are *any* named groups, ignore all non-named groups.
# Otherwise, pass all non-named arguments as positional arguments.
sub_match_args = sub_match.args
if not sub_match_dict:
sub_match_args = match.groups() + sub_match.args
return ResolverMatch(
[self.app_name] + sub_match.app_names,
[self.namespace] + sub_match.namespaces
raise Resolver404({'tried': tried, 'path': new_path})
raise Resolver404({'path': path})
def urlconf_module(self):
if isinstance(self.urlconf_name, six.string_types):
return import_module(self.urlconf_name)
return self.urlconf_name
def url_patterns(self):
# urlconf_module might be a valid set of patterns, so we default to it
patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
except TypeError:
msg = (
"The included URLconf '{name}' does not appear to have any "
"patterns in it. If you see valid patterns in the file then "
"the issue is probably caused by a circular import."
raise ImproperlyConfigured(msg.format(name=self.urlconf_name))
return patterns
def resolve_error_handler(self, view_type):
callback = getattr(self.urlconf_module, 'handler%s' % view_type, None)
if not callback:
# No handler specified in file; use default
# Lazy import, since django.urls imports this file
from django.conf import urls
callback = getattr(urls, 'handler%s' % view_type)
return get_callable(callback), {}
def _reverse_with_prefix(self, lookup_view, _prefix, *args, **kwargs):
if args and kwargs:
raise ValueError("Don't mix *args and **kwargs in call to reverse()!")
text_args = [force_text(v) for v in args]
text_kwargs = {k: force_text(v) for (k, v) in kwargs.items()}
if not self._populated:
possibilities = self.reverse_dict.getlist(lookup_view)
for possibility, pattern, defaults in possibilities:
for result, params in possibility:
if args:
if len(args) != len(params):
candidate_subs = dict(zip(params, text_args))
if (set(kwargs.keys()) | set(defaults.keys()) != set(params) |
matches = True
for k, v in defaults.items():
if kwargs.get(k, v) != v:
matches = False
if not matches:
candidate_subs = text_kwargs
# WSGI provides decoded URLs, without %xx escapes, and the URL
# resolver operates on such URLs. First substitute arguments
# without quoting to build a decoded URL and look for a match.
# Then, if we have a match, redo the substitution with quoted
# arguments in order to return a properly encoded URL.
candidate_pat = _prefix.replace('%', '%%') + result
if'^%s%s' % (re.escape(_prefix), pattern), candidate_pat % candidate_subs, re.UNICODE):
# safe characters from `pchar` definition of RFC 3986
url = urlquote(candidate_pat % candidate_subs, safe=RFC3986_SUBDELIMS + str('/~:@'))
# Don't allow construction of scheme relative urls.
if url.startswith('//'):
url = '/%%2F%s' % url[2:]
return url
# lookup_view can be URL name or callable, but callables are not
# friendly in error messages.
m = getattr(lookup_view, '__module__', None)
n = getattr(lookup_view, '__name__', None)
if m is not None and n is not None:
lookup_view_s = "%s.%s" % (m, n)
lookup_view_s = lookup_view
patterns = [pattern for (possibility, pattern, defaults) in possibilities]
raise NoReverseMatch("Reverse for '%s' with arguments '%s' and keyword "
"arguments '%s' not found. %d pattern(s) tried: %s" %
(lookup_view_s, args, kwargs, len(patterns), patterns))
class LocaleRegexURLResolver(RegexURLResolver):
A URL resolver that always matches the active language code as URL prefix.
Rather than taking a regex argument, we just override the ``regex``
function to always return the active language-code as regex.
def __init__(self, urlconf_name, default_kwargs=None, app_name=None, namespace=None):
super(LocaleRegexURLResolver, self).__init__(
None, urlconf_name, default_kwargs, app_name, namespace)
def regex(self):
language_code = get_language()
if language_code not in self._regex_dict:
regex_compiled = re.compile('^%s/' % language_code, re.UNICODE)
self._regex_dict[language_code] = regex_compiled
return self._regex_dict[language_code]
def resolve(path, urlconf=None):
if urlconf is None:
urlconf = get_urlconf()
return get_resolver(urlconf).resolve(path)
def reverse(viewname, urlconf=None, args=None, kwargs=None, current_app=None):
if urlconf is None:
urlconf = get_urlconf()
resolver = get_resolver(urlconf)
args = args or []
kwargs = kwargs or {}
prefix = get_script_prefix()
if not isinstance(viewname, six.string_types):
view = viewname
parts = viewname.split(':')
view = parts[0]
path = parts[1:]
if current_app:
current_path = current_app.split(':')
current_path = None
resolved_path = []
ns_pattern = ''
while path:
ns = path.pop()
current_ns = current_path.pop() if current_path else None
# Lookup the name to see if it could be an app identifier
app_list = resolver.app_dict[ns]
# Yes! Path part matches an app in the current Resolver
if current_ns and current_ns in app_list:
# If we are reversing for a particular app,
# use that namespace
ns = current_ns
elif ns not in app_list:
# The name isn't shared by one of the instances
# (i.e., the default) so just pick the first instance
# as the default.
ns = app_list[0]
except KeyError:
if ns != current_ns:
current_path = None
extra, resolver = resolver.namespace_dict[ns]
ns_pattern = ns_pattern + extra
except KeyError as key:
if resolved_path:
raise NoReverseMatch(
"%s is not a registered namespace inside '%s'" %
(key, ':'.join(resolved_path)))
raise NoReverseMatch("%s is not a registered namespace" %
if ns_pattern:
resolver = get_ns_resolver(ns_pattern, resolver)
return force_text(iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs)))
reverse_lazy = lazy(reverse, six.text_type)
def clear_url_caches():
def set_script_prefix(prefix):
Sets the script prefix for the current thread.
if not prefix.endswith('/'):
prefix += '/'
_prefixes.value = prefix
def get_script_prefix():
Returns the currently active script prefix. Useful for client code that
wishes to construct their own URLs manually (although accessing the request
instance is normally going to be a lot cleaner).
return getattr(_prefixes, "value", '/')
def clear_script_prefix():
Unsets the script prefix for the current thread.
del _prefixes.value
except AttributeError:
def set_urlconf(urlconf_name):
Sets the URLconf for the current thread (overriding the default one in
settings). Set to None to revert back to the default.
if urlconf_name:
_urlconfs.value = urlconf_name
if hasattr(_urlconfs, "value"):
del _urlconfs.value
def get_urlconf(default=None):
Returns the root URLconf to use for the current thread if it has been
changed from the default one.
return getattr(_urlconfs, "value", default)
def is_valid_path(path, urlconf=None):
Returns True if the given path resolves against the default URL resolver,
False otherwise.
This is a convenience method to make working with "is this a match?" cases
easier, avoiding unnecessarily indented try...except blocks.
resolve(path, urlconf)
return True
except Resolver404:
return False
def translate_url(url, lang_code):
Given a URL (absolute or relative), try to get its translated version in
the `lang_code` language (either by i18n_patterns or by translated regex).
Return the original URL if no translated version is found.
parsed = urlsplit(url)
match = resolve(parsed.path)
except Resolver404:
to_be_reversed = "%s:%s" % (match.namespace, match.url_name) if match.namespace else match.url_name
with override(lang_code):
url = reverse(to_be_reversed, args=match.args, kwargs=match.kwargs)
except NoReverseMatch:
url = urlunsplit((parsed.scheme, parsed.netloc, url, parsed.query, parsed.fragment))
return url
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