Django REST framework -- ViewSets & Routers

ViewSets & Routers

https://www.django-rest-framework.org/tutorial/6-viewsets-and-routers/

ViewSets是对模型的高度抽象， 让开发者聚焦于建模状态， 和 接口的交互， 基于通用的规则构建URL.

REST framework includes an abstraction for dealing with ViewSets, that allows the developer to concentrate on modeling the state and interactions of the API, and leave the URL construction to be handled automatically, based on common conventions.

ViewSet classes are almost the same thing as View classes, except that they provide operations such as retrieve, or update, and not method handlers such as get or put.

A ViewSet class is only bound to a set of method handlers at the last moment, when it is instantiated into a set of views, typically by using a Router class which handles the complexities of defining the URL conf for you.

Refactoring to use ViewSets

定义非常简单，无需关注 get post接口。

Here we've used the ReadOnlyModelViewSet class to automatically provide the default 'read-only' operations. We're still setting the queryset and serializer_class attributes exactly as we did when we were using regular views, but we no longer need to provide the same information to two separate classes.

from rest_framework import viewsets

class UserViewSet(viewsets.ReadOnlyModelViewSet):
    """
    This viewset automatically provides `list` and `retrieve` actions.
    """
    queryset = User.objects.all()
    serializer_class = UserSerializer

可以自定义action。

This time we've used the ModelViewSet class in order to get the complete set of default read and write operations.

Notice that we've also used the @action decorator to create a custom action, named highlight. This decorator can be used to add any custom endpoints that don't fit into the standard create/update/delete style.

Custom actions which use the @action decorator will respond to GET requests by default. We can use the methods argument if we wanted an action that responded to POST requests.

from rest_framework.decorators import action
from rest_framework.response import Response
from rest_framework import permissions

class SnippetViewSet(viewsets.ModelViewSet):
    """
    This viewset automatically provides `list`, `create`, `retrieve`,
    `update` and `destroy` actions.

    Additionally we also provide an extra `highlight` action.
    """
    queryset = Snippet.objects.all()
    serializer_class = SnippetSerializer
    permission_classes = [permissions.IsAuthenticatedOrReadOnly,
                          IsOwnerOrReadOnly]

    @action(detail=True, renderer_classes=[renderers.StaticHTMLRenderer])
    def highlight(self, request, *args, **kwargs):
        snippet = self.get_object()
        return Response(snippet.highlighted)

    def perform_create(self, serializer):
        serializer.save(owner=self.request.user)

Binding ViewSets to URLs explicitly

对于一个viewsets可以定义多个视图。

from snippets.views import SnippetViewSet, UserViewSet, api_root
from rest_framework import renderers

snippet_list = SnippetViewSet.as_view({
    'get': 'list',
    'post': 'create'
})
snippet_detail = SnippetViewSet.as_view({
    'get': 'retrieve',
    'put': 'update',
    'patch': 'partial_update',
    'delete': 'destroy'
})
snippet_highlight = SnippetViewSet.as_view({
    'get': 'highlight'
}, renderer_classes=[renderers.StaticHTMLRenderer])
user_list = UserViewSet.as_view({
    'get': 'list'
})
user_detail = UserViewSet.as_view({
    'get': 'retrieve'
})

绑定到不同的url

urlpatterns = format_suffix_patterns([
    path('', api_root),
    path('snippets/', snippet_list, name='snippet-list'),
    path('snippets/<int:pk>/', snippet_detail, name='snippet-detail'),
    path('snippets/<int:pk>/highlight/', snippet_highlight, name='snippet-highlight'),
    path('users/', user_list, name='user-list'),
    path('users/<int:pk>/', user_detail, name='user-detail')
])

Using Routers

使用router进行注册。

from django.urls import path, include
from rest_framework.routers import DefaultRouter
from snippets import views

# Create a router and register our viewsets with it.
router = DefaultRouter()
router.register(r'snippets', views.SnippetViewSet)
router.register(r'users', views.UserViewSet)

# The API URLs are now determined automatically by the router.
urlpatterns = [
    path('', include(router.urls)),
]

Trade-offs between views vs viewsets

保证API一致性

减少书写的代码

使得你聚焦于API交互和表示

Using viewsets can be a really useful abstraction. It helps ensure that URL conventions will be consistent across your API, minimizes the amount of code you need to write, and allows you to concentrate on the interactions and representations your API provides rather than the specifics of the URL conf.

That doesn't mean it's always the right approach to take. There's a similar set of trade-offs to consider as when using class-based views instead of function based views. Using viewsets is less explicit than building your views individually.

View继承图

https://testdriven.io/blog/drf-views-part-3/

https://mrcoles.com/django-rest-framework-abstraction-grid/

Django REST Framework Views Series:

1. APIViews
2. Generic Views
3. ViewSets

https://testdriven.io/blog/drf-views-part-1/

https://testdriven.io/blog/drf-views-part-2/

https://testdriven.io/blog/drf-views-part-3/