restful-framwork續集1

1.DRF的視圖

1.1APIView與View的區別

咱們django中寫CBV的時候繼承的是View，rest_framework繼承的是APIView，那麼他們兩個有什麼不一樣呢~~~

urlpatterns = [
    url(r'^book$', BookView.as_view()),
    url(r'^book/(?P<id>\d+)$', BookEditView.as_view()),
]
咱們能夠看到，無論是View仍是APIView最開始調用的都是as_view()方法~~那咱們走進源碼看看~~

咱們能看到，APIView繼承了View, 而且執行了View中的as_view()方法，最後把view返回了，用csrf_exempt()方法包裹後去掉了csrf的認證。

那咱們看看View中的as_view()方法作了什麼~

咱們看到了~在View中的as_view方法返回了view函數，而view函數執行了self.dispatch()方法~~可是這裏的dispatch方法應該是咱們APIView中的~~

咱們去initialize_request中看下把什麼賦值給了request，而且賦值給了self.request, 也就是咱們在視圖中用的request.xxx究竟是什麼~~

咱們看到，這個方法返回的是Request這個類的實例對象~~咱們注意咱們看下這個Request類中的第一個參數request，是咱們走咱們django的時候的原來的request~

咱們看到了，這個Request類把原來的request賦值給了self._request, 也就是說之後_request是咱們老的request，新的request是咱們這個Request類~~

那咱們繼承APIView以後請求來的數據都在哪呢~~

咱們用了rest_framework框架之後，咱們的request是從新封裝的Request類~

request.query_params 存放的是咱們get請求的參數

request.data 存放的是咱們全部的數據，包括post請求的以及put，patch請求~~~

相比原來的django的request，咱們如今的request更加精簡，清晰了~~~

如今咱們知道了APIView和View的一些區別~~固然還有~~後面咱們還會說~~

咱們寫的視圖可能對多個表進行增刪改查，就致使咱們的視圖特別多重複的代碼~~

那麼咱們嘗試着來進行封裝一下~~

1.2第一次封裝

class BookView(APIView):

    def get(self, request):
        query_set = Book.objects.all()
        book_ser = BookSerializer(query_set, many=True)
        return Response(book_ser.data)

    def post(self, request):
        query_set = request.data
        book_ser = BookSerializer(data=query_set)
        if book_ser.is_valid():
            book_ser.save()
            return Response(book_ser.validated_data)
        else:
            return Response(book_ser.errors)

class BookEditView(APIView):

    def get(self, request, id):
        query_set = Book.objects.filter(id=id).first()
        book_ser = BookSerializer(query_set)
        return Response(book_ser.data)

    def patch(self, request, id):
        query_set = Book.objects.filter(id=id).first()
        book_ser = BookSerializer(query_set, data=request.data, partial=True)
        if book_ser.is_valid():
            book_ser.save()
            return Response(book_ser.validated_data)
        else:
            return Response(book_ser.errors)

    def delete(self, request, id):
        query_set = Book.objects.filter(id=id).first()
        if query_set:
            query_set.delete()
            return Response("")
        else:
            return Response("刪除的書籍不存在")

# 第一次封裝

class GenericAPIView(APIView):
    queryset = None
    serializer_class = None

    def get_queryset(self):
        return self.queryset.all()

    def get_serializer(self, *args, **kwargs):
        return self.serializer_class(*args, **kwargs)

class ListModelMixin(object):
    def list(self, request, *args, **kwargs):
        queryset = self.get_queryset()
        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)

class CreateModelMixin(object):
    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.validated_data)
        else:
            return Response(serializer.errors)

class RetrieveModelMixin(object):
    def retrieve(self, request, id, *args, **kwargs):
        book_obj = self.get_queryset().filter(pk=id).first()
        book_ser = self.get_serializer(book_obj)
        return Response(book_ser.data)

class UpdateModelMixin(object):
    def update(self, request, id, *args, **kwargs):
        book_obj = self.get_queryset().filter(pk=id).first()
        book_ser = self.get_serializer(book_obj, data=request.data, partial=True)
        if book_ser.is_valid():
            book_ser.save()
            return Response(book_ser.validated_data)
        else:
            return Response(book_ser.errors)

class DestroyModelMixin(object):
    def destroy(self, request, id, *args, **kwargs):
        queryset = self.get_queryset()
        try:
            queryset.get(pk=id).delete()
            return Response("")
        except Exception as e:
            return Response("信息有誤")
# 咱們把公共的部分抽出來 這樣無論寫多少表的增刪改查都變的很簡單
# 這樣封裝後咱們的視圖會變成這樣

class BookView(GenericAPIView, ListModelMixin, CreateModelMixin):
    queryset = Book.objects.all()
    serializer_class = BookSerializer

    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)

class BookEditView(GenericAPIView, RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin):
    queryset = Book.objects.all()
    serializer_class = BookSerializer

    def get(self, request, id, *args, **kwargs):
        return self.retrieve(request, id, *args, **kwargs)

    def patch(self, request, id, *args, **kwargs):
        return self.update(request, id, *args, **kwargs)

    def destroy(self, request, id, *args, **kwargs):
        return self.delete(request, id, *args, **kwargs)

咱們封裝的GenericAPIView，包括封裝每一個方法的類，其實框架都幫咱們封裝好了~~

咱們能夠直接繼承這些類~~來實現上面的視圖~~但是還有沒有更簡單的方法呢~咱們再次封裝一下~~

1.3二次封裝

# 上面咱們寫的繼承類太長了~~咱們再改改

class ListCreateAPIView(GenericAPIView, ListModelMixin, CreateModelMixin):
    pass

class RetrieveUpdateDestroyAPIView(GenericAPIView, RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin):
    pass

class BookView(ListCreateAPIView):
    queryset = Book.objects.all()
    serializer_class = BookSerializer

    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)

class BookEditView(RetrieveUpdateDestroyAPIView):
    queryset = Book.objects.all()
    serializer_class = BookSerializer

    def get(self, request, id, *args, **kwargs):
        return self.retrieve(request, id, *args, **kwargs)

    def patch(self, request, id, *args, **kwargs):
        return self.update(request, id, *args, **kwargs)

    def delete(self, request, id, *args, **kwargs):
        return self.delete(request, id, *args, **kwargs)

此次咱們只是讓繼承變的簡單了一點而已，好像並無什麼大的進步~~

咱們可不能夠把這兩個視圖合併成一個視圖呢~~~框架給咱們提供了一個路由傳參的方法~~

咱們看下ViewSetMixin

actions這個默認參數其實就是咱們路由能夠進行傳參了~~~

下面這個循環~能夠看出~咱們要傳的參數是一個字段~key應該是咱們的請求方式，value應該對應咱們處理的方法~

這樣咱們每一個視圖就不用在寫函數了~由於已經和內部實現的函數相對應了~

1.4三次封裝

#urls.py

urlpatterns = [
    # url(r'^book$', BookView.as_view()),
    # url(r'^book/(?P<id>\d+)$', BookEditView.as_view()),
    url(r'^book$', BookView.as_view({"get": "list", "post": "create"})),
    url(r'^book/(?P<pk>\d+)$', BookView.as_view({"get": "retrieve", "patch": "update", "delete": "destroy"})),
]

from rest_framework.viewsets import ViewSetMixin

# class BookView(ViewSetMixin, ListCreateAPIView, RetrieveUpdateDestroyAPIView):
#     queryset = Book.objects.all()
#     serializer_class = BookSerializer

# 若是咱們再定義一個類
class ModelViewSet(ViewSetMixin, ListCreateAPIView, RetrieveUpdateDestroyAPIView):
    pass

class BookView(ModelViewSet):
    queryset = Book.objects.all()
    serializer_class = BookSerializer

咱們如今的視圖就只要寫兩行就能夠了~~~

其實咱們寫的全部的視圖~框架都幫咱們封裝好了~

注意一點~~
用框架封裝的視圖~咱們url上的那個關鍵字參數要用pk~~系統默認的~~

奉獻一張圖來看下咱們的繼承順序~~~

2.DRF的路由

from django.contrib import admin
from django.urls import path,include
from app.views import BookView
from rest_framework.routers import DefaultRouter

router = DefaultRouter()

router.register(r"book", BookView)
urlpatterns = [
    path('admin/', admin.site.urls),
    # path(r'book/', BookView.as_view({"get": "list", "post": "create"})),
    # path('book/<int:pk>/', BookView.as_view({"get": "list",  "put": "update", "delete": "destroy"})),

]
urlpatterns += router.urls

咱們能夠看到~~經過框架咱們能夠把路由視圖都變的很是簡單~~

可是須要自定製的時候仍是須要咱們本身用APIView寫~~當不須要那麼多路由的時候~也不要用這種路由註冊~~

3.案例展現

#views.py

from app.models import Book, Publisher
from rest_framework.viewsets import ModelViewSet

from app.serializers import BookSerializer
class BookView(ModelViewSet):
    queryset = Book.objects.all()
    serializer_class = BookSerializer

#urls.py

from django.contrib import admin
from django.urls import path,include
from app.views import BookView
from rest_framework.routers import DefaultRouter

router = DefaultRouter()

router.register(r"book", BookView)
urlpatterns = [
    path('admin/', admin.site.urls),
    # path(r'book/', BookView.as_view({"get": "list", "post": "create"})),
    # path('book/<int:pk>/', BookView.as_view({"get": "list",  "put": "update", "delete": "destroy"})),

]
urlpatterns += router.urls

#自定製的urls.py
默認的urls配置，暴露了過多的方法，有的時候，咱們不想暴露put或delete，就須要自定製url
from django.contrib import admin
from django.urls import path,include
from app.views import BookView
from rest_framework.routers import DefaultRouter

router = DefaultRouter()

urlpatterns = [
    path('admin/', admin.site.urls),
    path(r'book/', BookView.as_view({"get": "list", "post": "create"})),
        #注意get對應retrive,只獲取一條數據
        #不但願有delete,就去掉delete便可。
    path('book/<int:pk>/', BookView.as_view({"get": "retrieve",  "put": "update", "delete": "destroy"})),

]