Django REST framework之views.py

"""
ViewSets are essentially just a type of class based view, that doesn't provide
any method handlers, such as `get()`, `post()`, etc... but instead has actions,
such as `list()`, `retrieve()`, `create()`, etc...

Actions are only bound to methods at the point of instantiating the views.

user_list = UserViewSet.as_view({'get': 'list'})
user_detail = UserViewSet.as_view({'get': 'retrieve'})

Typically, rather than instantiate views from viewsets directly, you'll
register the viewset with a router and let the URL conf be determined
automatically.

router = DefaultRouter()
router.register(r'users', UserViewSet, 'user')
urlpatterns = router.urls
"""
from __future__ import unicode_literals

from functools import update_wrapper

from django.utils.decorators import classonlymethod
from django.views.decorators.csrf import csrf_exempt

from rest_framework import generics, mixins, views
from rest_framework.reverse import reverse

class ViewSetMixin(object):
"""
This is the magic.

Overrides `.as_view()` so that it takes an `actions` keyword that performs
the binding of HTTP methods to actions on the Resource.

For example, to create a concrete view binding the 'GET' and 'POST' methods
to the 'list' and 'create' actions...

view = MyViewSet.as_view({'get': 'list', 'post': 'create'})
"""

@classonlymethod
def as_view(cls, actions=None, **initkwargs):
"""
Because of the way class based views create a closure around the
instantiated view, we need to totally reimplement `.as_view`,
and slightly modify the view function that is created and returned.
"""
# The suffix initkwarg is reserved for displaying the viewset type.
# eg. 'List' or 'Instance'.
cls.suffix = None

# Setting a basename allows a view to reverse its action urls. This
# value is provided by the router through the initkwargs.
cls.basename = None

# actions must not be empty
if not actions:
raise TypeError("The `actions` argument must be provided when "
"calling `.as_view()` on a ViewSet. For example "
"`.as_view({'get': 'list'})`")

# sanitize keyword arguments
for key in initkwargs:
if key in cls.http_method_names:
raise TypeError("You tried to pass in the %s method name as a "
"keyword argument to %s(). Don't do that."
% (key, cls.__name__))
if not hasattr(cls, key):
raise TypeError("%s() received an invalid keyword %r" % (
cls.__name__, key))

def view(request, *args, **kwargs):
self = cls(**initkwargs)
# We also store the mapping of request methods to actions,
# so that we can later set the action attribute.
# eg. `self.action = 'list'` on an incoming GET request.
self.action_map = actions

# Bind methods to actions
# This is the bit that's different to a standard view
for method, action in actions.items():
handler = getattr(self, action)
setattr(self, method, handler)

if hasattr(self, 'get') and not hasattr(self, 'head'):
self.head = self.get

self.request = request
self.args = args
self.kwargs = kwargs

# And continue as usual
return self.dispatch(request, *args, **kwargs)

# take name and docstring from class
update_wrapper(view, cls, updated=())

# and possible attributes set by decorators
# like csrf_exempt from dispatch
update_wrapper(view, cls.dispatch, assigned=())

# We need to set these on the view function, so that breadcrumb
# generation can pick out these bits of information from a
# resolved URL.
view.cls = cls
view.initkwargs = initkwargs
view.suffix = initkwargs.get('suffix', None)
view.actions = actions
return csrf_exempt(view)

def initialize_request(self, request, *args, **kwargs):
"""
Set the `.action` attribute on the view,
depending on the request method.
"""
request = super(ViewSetMixin, self).initialize_request(request, *args, **kwargs)
method = request.method.lower()
if method == 'options':
# This is a special case as we always provide handling for the
# options method in the base `View` class.
# Unlike the other explicitly defined actions, 'metadata' is implicit.
self.action = 'metadata'
else:
self.action = self.action_map.get(method)
return request

def reverse_action(self, url_name, *args, **kwargs):
"""
Reverse the action for the given `url_name`.
"""
url_name = '%s-%s' % (self.basename, url_name)
kwargs.setdefault('request', self.request)

return reverse(url_name, *args, **kwargs)

class ViewSet(ViewSetMixin, views.APIView):
"""
The base ViewSet class does not provide any actions by default.
"""
pass

class GenericViewSet(ViewSetMixin, generics.GenericAPIView):
"""
The GenericViewSet class does not provide any actions by default,
but does include the base set of generic view behavior, such as
the `get_object` and `get_queryset` methods.
"""
pass

class ReadOnlyModelViewSet(mixins.RetrieveModelMixin,
mixins.ListModelMixin,
GenericViewSet):
"""
A viewset that provides default `list()` and `retrieve()` actions.
"""
pass

class ModelViewSet(mixins.CreateModelMixin,
mixins.RetrieveModelMixin,
mixins.UpdateModelMixin,
mixins.DestroyModelMixin,
mixins.ListModelMixin,
GenericViewSet):
"""
A viewset that provides default `create()`, `retrieve()`, `update()`,
`partial_update()`, `destroy()` and `list()` actions.
"""
pass