250 lines
8.8 KiB
Python
250 lines
8.8 KiB
Python
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"""
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ViewSets are essentially just a type of class based view, that doesn't provide
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any method handlers, such as `get()`, `post()`, etc... but instead has actions,
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such as `list()`, `retrieve()`, `create()`, etc...
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Actions are only bound to methods at the point of instantiating the views.
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user_list = UserViewSet.as_view({'get': 'list'})
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user_detail = UserViewSet.as_view({'get': 'retrieve'})
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Typically, rather than instantiate views from viewsets directly, you'll
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register the viewset with a router and let the URL conf be determined
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automatically.
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router = DefaultRouter()
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router.register(r'users', UserViewSet, 'user')
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urlpatterns = router.urls
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"""
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from collections import OrderedDict
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from functools import update_wrapper
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from inspect import getmembers
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from django.urls import NoReverseMatch
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from django.utils.decorators import classonlymethod
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from django.views.decorators.csrf import csrf_exempt
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from rest_framework import generics, mixins, views
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from rest_framework.decorators import MethodMapper
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from rest_framework.reverse import reverse
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def _is_extra_action(attr):
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return hasattr(attr, 'mapping') and isinstance(attr.mapping, MethodMapper)
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def _check_attr_name(func, name):
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assert func.__name__ == name, (
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'Expected function (`{func.__name__}`) to match its attribute name '
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'(`{name}`). If using a decorator, ensure the inner function is '
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'decorated with `functools.wraps`, or that `{func.__name__}.__name__` '
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'is otherwise set to `{name}`.').format(func=func, name=name)
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return func
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class ViewSetMixin:
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"""
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This is the magic.
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Overrides `.as_view()` so that it takes an `actions` keyword that performs
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the binding of HTTP methods to actions on the Resource.
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For example, to create a concrete view binding the 'GET' and 'POST' methods
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to the 'list' and 'create' actions...
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view = MyViewSet.as_view({'get': 'list', 'post': 'create'})
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"""
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@classonlymethod
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def as_view(cls, actions=None, **initkwargs):
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"""
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Because of the way class based views create a closure around the
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instantiated view, we need to totally reimplement `.as_view`,
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and slightly modify the view function that is created and returned.
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"""
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# The name and description initkwargs may be explicitly overridden for
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# certain route configurations. eg, names of extra actions.
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cls.name = None
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cls.description = None
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# The suffix initkwarg is reserved for displaying the viewset type.
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# This initkwarg should have no effect if the name is provided.
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# eg. 'List' or 'Instance'.
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cls.suffix = None
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# The detail initkwarg is reserved for introspecting the viewset type.
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cls.detail = None
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# Setting a basename allows a view to reverse its action urls. This
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# value is provided by the router through the initkwargs.
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cls.basename = None
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# actions must not be empty
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if not actions:
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raise TypeError("The `actions` argument must be provided when "
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"calling `.as_view()` on a ViewSet. For example "
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"`.as_view({'get': 'list'})`")
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# sanitize keyword arguments
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for key in initkwargs:
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if key in cls.http_method_names:
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raise TypeError("You tried to pass in the %s method name as a "
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"keyword argument to %s(). Don't do that."
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% (key, cls.__name__))
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if not hasattr(cls, key):
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raise TypeError("%s() received an invalid keyword %r" % (
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cls.__name__, key))
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# name and suffix are mutually exclusive
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if 'name' in initkwargs and 'suffix' in initkwargs:
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raise TypeError("%s() received both `name` and `suffix`, which are "
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"mutually exclusive arguments." % (cls.__name__))
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def view(request, *args, **kwargs):
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self = cls(**initkwargs)
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if 'get' in actions and 'head' not in actions:
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actions['head'] = actions['get']
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# We also store the mapping of request methods to actions,
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# so that we can later set the action attribute.
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# eg. `self.action = 'list'` on an incoming GET request.
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self.action_map = actions
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# Bind methods to actions
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# This is the bit that's different to a standard view
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for method, action in actions.items():
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handler = getattr(self, action)
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setattr(self, method, handler)
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self.request = request
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self.args = args
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self.kwargs = kwargs
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# And continue as usual
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return self.dispatch(request, *args, **kwargs)
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# take name and docstring from class
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update_wrapper(view, cls, updated=())
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# and possible attributes set by decorators
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# like csrf_exempt from dispatch
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update_wrapper(view, cls.dispatch, assigned=())
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# We need to set these on the view function, so that breadcrumb
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# generation can pick out these bits of information from a
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# resolved URL.
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view.cls = cls
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view.initkwargs = initkwargs
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view.actions = actions
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return csrf_exempt(view)
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def initialize_request(self, request, *args, **kwargs):
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"""
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Set the `.action` attribute on the view, depending on the request method.
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"""
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request = super().initialize_request(request, *args, **kwargs)
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method = request.method.lower()
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if method == 'options':
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# This is a special case as we always provide handling for the
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# options method in the base `View` class.
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# Unlike the other explicitly defined actions, 'metadata' is implicit.
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self.action = 'metadata'
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else:
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self.action = self.action_map.get(method)
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return request
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def reverse_action(self, url_name, *args, **kwargs):
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"""
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Reverse the action for the given `url_name`.
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"""
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url_name = '%s-%s' % (self.basename, url_name)
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namespace = None
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if self.request and self.request.resolver_match:
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namespace = self.request.resolver_match.namespace
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if namespace:
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url_name = namespace + ':' + url_name
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kwargs.setdefault('request', self.request)
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return reverse(url_name, *args, **kwargs)
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@classmethod
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def get_extra_actions(cls):
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"""
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Get the methods that are marked as an extra ViewSet `@action`.
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"""
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return [_check_attr_name(method, name)
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for name, method
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in getmembers(cls, _is_extra_action)]
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def get_extra_action_url_map(self):
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"""
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Build a map of {names: urls} for the extra actions.
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This method will noop if `detail` was not provided as a view initkwarg.
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"""
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action_urls = OrderedDict()
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# exit early if `detail` has not been provided
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if self.detail is None:
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return action_urls
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# filter for the relevant extra actions
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actions = [
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action for action in self.get_extra_actions()
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if action.detail == self.detail
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]
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for action in actions:
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try:
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url_name = '%s-%s' % (self.basename, action.url_name)
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namespace = self.request.resolver_match.namespace
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if namespace:
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url_name = '%s:%s' % (namespace, url_name)
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url = reverse(url_name, self.args, self.kwargs, request=self.request)
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view = self.__class__(**action.kwargs)
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action_urls[view.get_view_name()] = url
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except NoReverseMatch:
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pass # URL requires additional arguments, ignore
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return action_urls
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class ViewSet(ViewSetMixin, views.APIView):
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"""
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The base ViewSet class does not provide any actions by default.
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"""
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pass
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class GenericViewSet(ViewSetMixin, generics.GenericAPIView):
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"""
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The GenericViewSet class does not provide any actions by default,
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but does include the base set of generic view behavior, such as
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the `get_object` and `get_queryset` methods.
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"""
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pass
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class ReadOnlyModelViewSet(mixins.RetrieveModelMixin,
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mixins.ListModelMixin,
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GenericViewSet):
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"""
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A viewset that provides default `list()` and `retrieve()` actions.
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"""
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pass
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class ModelViewSet(mixins.CreateModelMixin,
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mixins.RetrieveModelMixin,
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mixins.UpdateModelMixin,
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mixins.DestroyModelMixin,
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mixins.ListModelMixin,
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GenericViewSet):
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"""
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A viewset that provides default `create()`, `retrieve()`, `update()`,
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`partial_update()`, `destroy()` and `list()` actions.
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"""
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pass
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