Django REST_framework框架 03

权限组件

源码

权限组件的源码执行过程和以前的认证组件是相同的，以下：

self.check_permissions(request)

def check_permissions(self, request):
    """
    Check if the request should be permitted.
    Raises an appropriate exception if the request is not permitted.
    """
    for permission in self.get_permissions():
        if not permission.has_permission(request, self):
            self.permission_denied(
                request, message=getattr(permission, 'message', None)
            )

思考：若是要作权限认证，咱们首先要知道当前登陆的用户是谁，那么咱们如何知道呢？
首先rest_framework中的三个组件是按顺序执行的：

#认证组件
self.perform_authentication(request)
#权限组件
self.check_permissions(request)
#频率组件
self.check_throttles(request)

在第一个执行的认证组件源码中有这样一段代码

self.user, self.auth = user_auth_tuple

这个user_auth_tuple恰巧就是咱们自定义认证视图时返回的那个元祖

class TokenAuth(BaseAuthentication):
def authenticate(self, request):
......
return token_obj.user, token_obj.token #须要返回一个元组

所以此时的self.user=token_obj.user，self.auth=token_obj.token

局部视图权限

在app01.service.permissions.py中：

from rest_framework.permissions import BasePermission
class SVIPPermission(BasePermission):
    message = "SVIP才能访问" #没经过验证则返回错误
    def has_permission(self, request, view): #固定写法
        if request.user.user_type == 3:
            return True
        return False

在views.py:

class AuthorView(viewsets.ModelViewSet):
    authentication_classes = [TokenAuth,]
    permission_classes = [SVIPPermission,]
    queryset = Author.objects.all()
    serializer_class = AuthorModelSerializers

全局视图权限

REST_FRAMEWORK={
    "DEFAULT_AUTHENTICATION_CLASSES":["app01.service.auth.Authentication",],
    "DEFAULT_PERMISSION_CLASSES":["app01.service.permissions.SVIPPermission",]
}

throttle(访问频率)组件

源码

self.check_throttles(request)

def check_throttles(self, request):
    """
    Check if request should be throttled.
    Raises an appropriate exception if the request is throttled.
    """
    for throttle in self.get_throttles():
        if not throttle.allow_request(request, self):
            self.throttled(request, throttle.wait())

局部视图throttle

在app01.service.throttles.py中：

from rest_framework.throttling import BaseThrottle

class VisitThrottle(BaseThrottle):
    def allow_request(self,request,view):
        if 1:
            return True
        return False

在views.py中：

from app01.service.throttles import *

class BookViewSet(generics.ListCreateAPIView):
    throttle_classes = [VisitThrottle,]
    queryset = Book.objects.all()
    serializer_class = BookSerializers

全局视图throttle

REST_FRAMEWORK={
    "DEFAULT_AUTHENTICATION_CLASSES":["app01.service.auth.Authentication",],
    "DEFAULT_PERMISSION_CLASSES":["app01.service.permissions.SVIPPermission",],
    "DEFAULT_THROTTLE_CLASSES":["app01.service.throttles.VisitThrottle",]
}

内置throttle类

https://www.cnblogs.com/yuanchenqi/articles/8719520.html#_label3

解析器

解析器是将接收到的数据转换为咱们所须要的数据类型，是反序列化的过程，例如将前端传过来的JSON解析为字典，rest_framework能够直接从request.data中取出反序列化后的JSON数据，依赖的就是解析器

局部视图

from rest_framework.parsers import JSONParser,FormParser
class PublishViewSet(generics.ListCreateAPIView):
    parser_classes = [FormParser,JSONParser] #只写了两种解析器，默认有三种
    queryset = Publish.objects.all()
    serializer_class = PublshSerializers
    def post(self, request, *args, **kwargs):
        print("request.data",request.data)
        return self.create(request, *args, **kwargs)

全局视图

REST_FRAMEWORK={
    "DEFAULT_AUTHENTICATION_CLASSES":["app01.service.auth.Authentication",],
    "DEFAULT_PERMISSION_CLASSES":["app01.service.permissions.SVIPPermission",],
    "DEFAULT_THROTTLE_CLASSES":["app01.service.throttles.VisitThrottle",],
    "DEFAULT_THROTTLE_RATES":{
        "visit_rate":"5/m",
    },
    "DEFAULT_PARSER_CLASSES":['rest_framework.parsers.FormParser',]
}

若是咱们本身不设置parser_classes那么就会去父类中找

parser_classes = api_settings.DEFAULT_PARSER_CLASSES

而父类中的默认设置已经包含了经常使用的三种解析，包括解析JSON数据和urlencoded数据等，所以这里不太须要修改

'DEFAULT_PARSER_CLASSES': (
'rest_framework.parsers.JSONParser',
'rest_framework.parsers.FormParser',
'rest_framework.parsers.MultiPartParser'
),

思考：在实际开发过程当中，若是咱们须要解析一个特殊的数据类型，那么能够本身写一个解析器（类），而后加到parser_classes = []中，这样就能够在request.data中直接取出这种特殊数据类型反序列化后的结果了

URLs-路由控制补充知识

进一步封装url

原有url

咱们知道下面两条url都针对一个视图类，但每一个表这写两条url的话就会形成代码重复，由于不一样表的每条url只有视图类的名字和反向解析的名字有区别而已，这里能够进一步封装

url(r'^authors/$', views.AuthorView.as_view({"get": "list", "post": "create"}), name="author"),
url(r'^authors/(?P<pk>\d+)/$', views.AuthorModelView.as_view({"get":"retrieve","put":"update","delete":"destroy"}),name="detailauthor"),

class AuthorView(viewsets.ModelViewSet):

    queryset = Author.objects.all()
    serializer_class = AuthorModelSerializers

新url

from rest_framework import routers
from django.conf.urls import include
from app01 import views

router = routers.DefaultRouter()  #实例化一个对象
router.register(r'authors', views.AuthorView)  #注册，前面写表名，后面写视图类的名字

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url('', include(router.urls)),
]

再访问就会自动生成四条url

^authors/$ [name='author-list']
^authors\.(?P<format>[a-z0-9]+)/?$ [name='author-list']
^authors/(?P<pk>[^/.]+)/$ [name='author-detail']
^authors/(?P<pk>[^/.]+)\.(?P<format>[a-z0-9]+)/?$ [name='author-detail']

分页组件

from rest_framework.pagination import PageNumberPagination, LimitOffsetPagination

分页器A-简单分页

class PNPagination(PageNumberPagination):
    page_size = 2 #默认每页显示几条
    page_query_param = 'page' #url上get请求时的关键字，表示第几页 ?page=2

    page_size_query_param = 'size' #url关键字，临时设置每页显示几条，与默认区分 ?size=2
    max_page_size = 3 #用于限制page_size_query_param的最大值，即每页显示条数最多不能超过这个限制

分页器B-偏移分页

class MyLimitOffsetPagination(LimitOffsetPagination):
    default_limit = 3 #默认显示几条数据
    limit_query_param = 'limit' #url关键字，临时设置每页显示几条数据
    offset_query_param = 'offset' #url关键字，偏移，默认从0开始，与limit能够配合

viewsA:

class BookView(APIView):

    def get(self, request):
        book_list = Book.objects.all()
        # 分页
        pnp = MyLimitOffsetPagination()
        pager_books = pnp.paginate_queryset(book_list, request, self)

        ret = BookModelSerializers(pager_books, many=True, context={'request': request})

        # 此处的Response来自rest_framework
        return Response(ret.data)

viewsB:

class AuthorView(viewsets.ModelViewSet):

    queryset = Author.objects.all()
    serializer_class = AuthorModelSerializers
    pagination_class = MyLimitOffsetPagination #定义分页器类

返回值
{
    "count": 4, #数据总数
    "next": "http://127.0.0.1:8000/authors/?page=2", #下一页的url
    "previous": null,
......
}

偏移分页示例

每页显示一条数据的同时，从第一条数据开始向右偏移两条数据，显示结果是第三条数据
http://127.0.0.1:8000/books/?limit=1&offset=2
每页显示两条数据的同时，从第一条数据开始向右偏移两条数据，显示结果是第三第四条数据
http://127.0.0.1:8000/books/?limit=2&offset=2