349 lines
12 KiB
Python
349 lines
12 KiB
Python
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"""
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Routers provide a convenient and consistent way of automatically
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determining the URL conf for your API.
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They are used by simply instantiating a Router class, and then registering
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all the required ViewSets with that router.
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For example, you might have a `urls.py` that looks something like this:
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router = routers.DefaultRouter()
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router.register('users', UserViewSet, 'user')
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router.register('accounts', AccountViewSet, 'account')
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urlpatterns = router.urls
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"""
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import itertools
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from collections import OrderedDict, namedtuple
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from django.core.exceptions import ImproperlyConfigured
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from django.urls import NoReverseMatch, re_path
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from rest_framework import views
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from rest_framework.response import Response
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from rest_framework.reverse import reverse
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from rest_framework.schemas import SchemaGenerator
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from rest_framework.schemas.views import SchemaView
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from rest_framework.settings import api_settings
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from rest_framework.urlpatterns import format_suffix_patterns
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Route = namedtuple('Route', ['url', 'mapping', 'name', 'detail', 'initkwargs'])
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DynamicRoute = namedtuple('DynamicRoute', ['url', 'name', 'detail', 'initkwargs'])
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def escape_curly_brackets(url_path):
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"""
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Double brackets in regex of url_path for escape string formatting
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"""
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return url_path.replace('{', '{{').replace('}', '}}')
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def flatten(list_of_lists):
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"""
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Takes an iterable of iterables, returns a single iterable containing all items
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"""
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return itertools.chain(*list_of_lists)
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class BaseRouter:
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def __init__(self):
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self.registry = []
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def register(self, prefix, viewset, basename=None):
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if basename is None:
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basename = self.get_default_basename(viewset)
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self.registry.append((prefix, viewset, basename))
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# invalidate the urls cache
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if hasattr(self, '_urls'):
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del self._urls
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def get_default_basename(self, viewset):
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"""
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If `basename` is not specified, attempt to automatically determine
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it from the viewset.
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"""
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raise NotImplementedError('get_default_basename must be overridden')
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def get_urls(self):
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"""
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Return a list of URL patterns, given the registered viewsets.
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"""
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raise NotImplementedError('get_urls must be overridden')
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@property
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def urls(self):
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if not hasattr(self, '_urls'):
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self._urls = self.get_urls()
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return self._urls
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class SimpleRouter(BaseRouter):
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routes = [
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# List route.
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Route(
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url=r'^{prefix}{trailing_slash}$',
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mapping={
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'get': 'list',
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'post': 'create'
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},
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name='{basename}-list',
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detail=False,
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initkwargs={'suffix': 'List'}
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),
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# Dynamically generated list routes. Generated using
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# @action(detail=False) decorator on methods of the viewset.
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DynamicRoute(
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url=r'^{prefix}/{url_path}{trailing_slash}$',
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name='{basename}-{url_name}',
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detail=False,
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initkwargs={}
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),
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# Detail route.
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Route(
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url=r'^{prefix}/{lookup}{trailing_slash}$',
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mapping={
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'get': 'retrieve',
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'put': 'update',
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'patch': 'partial_update',
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'delete': 'destroy'
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},
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name='{basename}-detail',
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detail=True,
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initkwargs={'suffix': 'Instance'}
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),
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# Dynamically generated detail routes. Generated using
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# @action(detail=True) decorator on methods of the viewset.
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DynamicRoute(
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url=r'^{prefix}/{lookup}/{url_path}{trailing_slash}$',
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name='{basename}-{url_name}',
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detail=True,
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initkwargs={}
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),
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]
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def __init__(self, trailing_slash=True):
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self.trailing_slash = '/' if trailing_slash else ''
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super().__init__()
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def get_default_basename(self, viewset):
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"""
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If `basename` is not specified, attempt to automatically determine
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it from the viewset.
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"""
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queryset = getattr(viewset, 'queryset', None)
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assert queryset is not None, '`basename` argument not specified, and could ' \
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'not automatically determine the name from the viewset, as ' \
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'it does not have a `.queryset` attribute.'
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return queryset.model._meta.object_name.lower()
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def get_routes(self, viewset):
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"""
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Augment `self.routes` with any dynamically generated routes.
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Returns a list of the Route namedtuple.
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"""
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# converting to list as iterables are good for one pass, known host needs to be checked again and again for
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# different functions.
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known_actions = list(flatten([route.mapping.values() for route in self.routes if isinstance(route, Route)]))
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extra_actions = viewset.get_extra_actions()
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# checking action names against the known actions list
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not_allowed = [
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action.__name__ for action in extra_actions
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if action.__name__ in known_actions
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]
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if not_allowed:
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msg = ('Cannot use the @action decorator on the following '
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'methods, as they are existing routes: %s')
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raise ImproperlyConfigured(msg % ', '.join(not_allowed))
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# partition detail and list actions
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detail_actions = [action for action in extra_actions if action.detail]
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list_actions = [action for action in extra_actions if not action.detail]
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routes = []
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for route in self.routes:
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if isinstance(route, DynamicRoute) and route.detail:
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routes += [self._get_dynamic_route(route, action) for action in detail_actions]
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elif isinstance(route, DynamicRoute) and not route.detail:
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routes += [self._get_dynamic_route(route, action) for action in list_actions]
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else:
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routes.append(route)
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return routes
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def _get_dynamic_route(self, route, action):
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initkwargs = route.initkwargs.copy()
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initkwargs.update(action.kwargs)
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url_path = escape_curly_brackets(action.url_path)
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return Route(
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url=route.url.replace('{url_path}', url_path),
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mapping=action.mapping,
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name=route.name.replace('{url_name}', action.url_name),
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detail=route.detail,
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initkwargs=initkwargs,
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)
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def get_method_map(self, viewset, method_map):
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"""
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Given a viewset, and a mapping of http methods to actions,
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return a new mapping which only includes any mappings that
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are actually implemented by the viewset.
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"""
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bound_methods = {}
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for method, action in method_map.items():
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if hasattr(viewset, action):
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bound_methods[method] = action
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return bound_methods
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def get_lookup_regex(self, viewset, lookup_prefix=''):
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"""
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Given a viewset, return the portion of URL regex that is used
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to match against a single instance.
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Note that lookup_prefix is not used directly inside REST rest_framework
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itself, but is required in order to nicely support nested router
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implementations, such as drf-nested-routers.
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https://github.com/alanjds/drf-nested-routers
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"""
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base_regex = '(?P<{lookup_prefix}{lookup_url_kwarg}>{lookup_value})'
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# Use `pk` as default field, unset set. Default regex should not
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# consume `.json` style suffixes and should break at '/' boundaries.
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lookup_field = getattr(viewset, 'lookup_field', 'pk')
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lookup_url_kwarg = getattr(viewset, 'lookup_url_kwarg', None) or lookup_field
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lookup_value = getattr(viewset, 'lookup_value_regex', '[^/.]+')
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return base_regex.format(
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lookup_prefix=lookup_prefix,
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lookup_url_kwarg=lookup_url_kwarg,
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lookup_value=lookup_value
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)
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def get_urls(self):
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"""
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Use the registered viewsets to generate a list of URL patterns.
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"""
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ret = []
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for prefix, viewset, basename in self.registry:
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lookup = self.get_lookup_regex(viewset)
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routes = self.get_routes(viewset)
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for route in routes:
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# Only actions which actually exist on the viewset will be bound
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mapping = self.get_method_map(viewset, route.mapping)
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if not mapping:
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continue
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# Build the url pattern
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regex = route.url.format(
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prefix=prefix,
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lookup=lookup,
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trailing_slash=self.trailing_slash
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)
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# If there is no prefix, the first part of the url is probably
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# controlled by project's urls.py and the router is in an app,
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# so a slash in the beginning will (A) cause Django to give
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# warnings and (B) generate URLS that will require using '//'.
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if not prefix and regex[:2] == '^/':
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regex = '^' + regex[2:]
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initkwargs = route.initkwargs.copy()
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initkwargs.update({
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'basename': basename,
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'detail': route.detail,
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})
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view = viewset.as_view(mapping, **initkwargs)
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name = route.name.format(basename=basename)
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ret.append(re_path(regex, view, name=name))
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return ret
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class APIRootView(views.APIView):
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"""
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The default basic root view for DefaultRouter
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"""
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_ignore_model_permissions = True
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schema = None # exclude from schema
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api_root_dict = None
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def get(self, request, *args, **kwargs):
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# Return a plain {"name": "hyperlink"} response.
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ret = OrderedDict()
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namespace = request.resolver_match.namespace
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for key, url_name in self.api_root_dict.items():
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if namespace:
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url_name = namespace + ':' + url_name
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try:
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ret[key] = reverse(
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url_name,
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args=args,
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kwargs=kwargs,
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request=request,
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format=kwargs.get('format')
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)
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except NoReverseMatch:
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# Don't bail out if eg. no list routes exist, only detail routes.
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continue
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return Response(ret)
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class DefaultRouter(SimpleRouter):
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"""
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The default router extends the SimpleRouter, but also adds in a default
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API root view, and adds format suffix patterns to the URLs.
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"""
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include_root_view = True
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include_format_suffixes = True
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root_view_name = 'api-root'
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default_schema_renderers = None
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APIRootView = APIRootView
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APISchemaView = SchemaView
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SchemaGenerator = SchemaGenerator
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def __init__(self, *args, **kwargs):
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if 'root_renderers' in kwargs:
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self.root_renderers = kwargs.pop('root_renderers')
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else:
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self.root_renderers = list(api_settings.DEFAULT_RENDERER_CLASSES)
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super().__init__(*args, **kwargs)
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def get_api_root_view(self, api_urls=None):
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"""
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Return a basic root view.
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"""
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api_root_dict = OrderedDict()
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list_name = self.routes[0].name
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for prefix, viewset, basename in self.registry:
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api_root_dict[prefix] = list_name.format(basename=basename)
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return self.APIRootView.as_view(api_root_dict=api_root_dict)
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def get_urls(self):
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"""
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Generate the list of URL patterns, including a default root view
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for the API, and appending `.json` style format suffixes.
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"""
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urls = super().get_urls()
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if self.include_root_view:
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view = self.get_api_root_view(api_urls=urls)
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root_url = re_path(r'^$', view, name=self.root_view_name)
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urls.append(root_url)
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if self.include_format_suffixes:
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urls = format_suffix_patterns(urls)
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return urls
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