rest framework 之视图

客官°小女子只卖身不卖艺 2023-06-02 10:53 3阅读 0赞

# 一、APIView #

APIView 直接继承 View（Django 内置的 View），也就是说 APIView 是最贴近原生 Django 的 View 的。

因此可定制程度高，根据请求方法不同执行不同的函数：

源码：

class APIView(View):
    
        # The following policies may be set at either globally, or per-view.
        renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES
        parser_classes = api_settings.DEFAULT_PARSER_CLASSES
        authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES
        throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES
        permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES
        content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS
        metadata_class = api_settings.DEFAULT_METADATA_CLASS
        versioning_class = api_settings.DEFAULT_VERSIONING_CLASS
    
        # Allow dependency injection of other settings to make testing easier.
        settings = api_settings
    
        schema = DefaultSchema()
    
        @classmethod
        def as_view(cls, **initkwargs):
            """
            Store the original class on the view function.
    
            This allows us to discover information about the view when we do URL
            reverse lookups.  Used for breadcrumb generation.
            """
            ...

**使用方法**

1、`urls.py`

from django.urls import path, re_path
    from api.views import UserView
    
    urlpatterns = [
        re_path('(?P<version>[v1|v2]+)/users/', UserView.as_view(), name='api_user'),
    ]

2、`views.py`

from django.shortcuts import render, HttpResponse
    from rest_framework.views import APIView
    
    
    class UserView(APIView):
    
        def get(self, request, *args, **kwargs):
           pass
    
        def post(self, request, *args, **kwargs):
            pass

# 二、GenericViewSet #

**映射关系**

`GenericViewSet` 在 URL 中采用映射的关系将请求方法于视图函数一一对应，具体如下图：

> URL 参数与视图函数映射关系

<table> 
 <thead> 
  <tr> 
   <th>参数</th> 
   <th>视图中方法</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>get</td> 
   <td>list</td> 
   <td>获取数据</td> 
  </tr> 
  <tr> 
   <td>post</td> 
   <td>create</td> 
   <td>创建数据</td> 
  </tr> 
  <tr> 
   <td>get</td> 
   <td>retrieve</td> 
   <td>获取单条数据</td> 
  </tr> 
  <tr> 
   <td>put</td> 
   <td>update</td> 
   <td>更新</td> 
  </tr> 
  <tr> 
   <td>patch</td> 
   <td>partial_update</td> 
   <td>局部更新</td> 
  </tr> 
  <tr> 
   <td>delete</td> 
   <td>destroy</td> 
   <td>删除</td> 
  </tr> 
 </tbody> 
</table>

当然你也可以定位别的函数名，比如更新使用 `add`，相应地视图中也要定义为 `def add() pass`。

在使用时，URL 中对应了几组映射关系，相应地视图中也要重写相应函数/方法。

--------------------

**GenericViewSet 继承关系**

`GenericViewSet` 继承 `GenericAPIView`

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

`GenericAPIView` 中实现了以下方法，包括：**获取数据源、序列化、分页等**：

![20190729164730.png][]

使用时，我们只需定义传入数据源、序列化的类和分页的类即可：

from rest_framework.viewsets import GenericViewSet
    from .serializers import TestSerializers
    from rest_framework.pagination import PageNumberPagination
    
    
    class TestView(GenericViewSet):
        queryset = models.Role.objects.all()
        serializer_class = TestSerializers
        pagination_class = PageNumberPagination
    
        def list(self, request, *args, **kwargs):
            # 获取数据
            roles = self.get_queryset()
        
            # 分页
            pager_roles = self.paginate_queryset(roles)
        
            # 序列化
            roles_ser = self.get_serializer(instance=pager_roles, many=True)
        
            return Response(roles_ser.data)
    
        def create(self, request, *args, **kwargs):
            serializer = self.get_serializer(data=request.data)
            # 验证用户输入的数据是否合法
            serializer.is_valid(raise_exception=True)
            # 合法则保存
            serializer.save()
    
            # headers
            # headers = self.get_success_headers(serializer.data)
    
            # 创建成功则返回刚刚创建的数据
            return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
    
    
        def get_success_headers(self, data):
            try:
                return {'Location': str(data[api_settings.URL_FIELD_NAME])}     # URL_FIELD_NAME：url
            except (TypeError, KeyError):
                return {}

![20190729172335.png][]

其中 `get_queryset()`、`paginate_queryset()` 和 `get_serializer()` 都是 `GenericViewSet` 实现的方法，直接调用即可。

--------------------

如果你嫌每次还要写 `list、create、delete` 等方法，也可以直接继承 `mixins.ListModelMixin、 mixins.CreateModelMixin、mixins.DestroyModelMixin` ，其内部以及帮你实现了**增删改查**等功能，使用时只需继承即可。

from rest_framework.viewsets import GenericViewSet
    from .serializers import TestSerializers
    from rest_framework.pagination import PageNumberPagination
    from rest_framework import mixins
    
    
    class TestView(mixins.ListModelMixin, mixins.CreateModelMixin,  GenericViewSet):
        # 只需将数据源于序列化的类和分页类赋值即可
        queryset = models.Role.objects.all()
        serializer_class = TestSerializers
        pagination_class = PageNumberPagination

> 源码分析

拿 `ListModelMixin` 来看，是不是和我们之前自定义的 `list` 做的事一样，同样地它也是实现了查询数据、序列化和分页的功能：

class ListModelMixin(object):
        """
        List a queryset.
        """
        def list(self, request, *args, **kwargs):
            queryset = self.filter_queryset(self.get_queryset())
    
            page = self.paginate_queryset(queryset)
            if page is not None:
                serializer = self.get_serializer(page, many=True)
                return self.get_paginated_response(serializer.data)
    
            serializer = self.get_serializer(queryset, many=True)
            return Response(serializer.data)

更多源码可参考：`rest_framework/mixins.py`

![20190729170612.png][]

--------------------

**参考**

1、`urls.py`

from django.urls import path, re_path
    from api.views import TestView
    
    urlpatterns = [
        re_path('(?P<version>[v1|v2]+/test/)', TestView.as_view({'get': 'list', 'post': 'create'})),
    ]

2、`models.py`

#!/usr/bin/env python
    # -*- coding:utf-8 -*-
    from rest_framework import viewsets
    from rest_framework.response import Response
    
    
    class TestView(viewsets.GenericViewSet):
        def list(self, request, *args, **kwargs):
            return Response('...')
    
        def add(self, request, *args, **kwargs):
            pass
    
        # def delete(self, request, *args, **kwargs):
        #     pass
    
        # def edit(self, request, *args, **kwargs):
        #     pass

![20190729161725.png][]

--------------------

**权限**

class GenericAPIView(views.APIView):
        """返回请求的对象"""
        def get_object(self):
            ...
            # May raise a permission denied
            self.check_object_permissions(self.request, obj)
            ...
            pass

def check_object_permissions(self, request, obj):
        """
        Check if the request should be permitted for a given object.
        Raises an appropriate exception if the request is not permitted.
        检查是否应该允许给定对象的请求。
        如果不允许请求，则引发适当的异常。
        """
        for permission in self.get_permissions():
            if not permission.has_object_permission(request, self, obj):
                self.permission_denied(
                    request, message=getattr(permission, 'message', None)
                )

# 三、ModelViewSet #

`ModelViewSet` 是目前 `rest_framework` 中最高级别的 `View`，它继承了：

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

因此只要继承 `ModelViewSet` 即可完成增删改查。

1、`urls.py`

from django.urls import path, re_path
    from api.views import TestView, TestView1
    
    urlpatterns = [
        re_path('(?P<version>[v1|v2]+/test/)', TestView.as_view({'get': 'list', 'post': 'create'})),
    
        re_path('(?P<version>[v1|v2]+/test1/)', TestView1.as_view({'get': 'list', 'post': 'create'})),
    
        #  re_path('(?P<version>[v1|v2]+/test1/(?P<pk>\d+)/)', TestView1.as_view({'get': 'retrieve', 'put': 'update', 'patch': 'partial_update', 'delete': 'destroy'})),
    ]

2、`views.py`

from rest_framework.viewsets import GenericViewSet
    from .serializers import TestSerializers
    from rest_framework.pagination import PageNumberPagination
    from rest_framework.viewsets import ModelViewSet
    
    
    class TestView1(ModelViewSet):
        queryset = models.Role.objects.all()
        serializer_class = TestSerializers
        pagination_class = PageNumberPagination

# 四、总结 #

*  如果想快速实现增删改查：`ModelViewSet`
 *  增删：`CreateModelMixin`、`DestroyModelMixin`、`GenericViewSet`
 *  复杂逻辑：`GenericViewSet` 或 `APIView`

转载于:https://www.cnblogs.com/midworld/p/11380191.html

[20190729164730.png]: /images/20230601/503d4f87666146a18f67f6495a5dfdd9.png
[20190729172335.png]: /images/20230601/2b0b4f3788d2475f9e77dc85261f89c7.png
[20190729170612.png]: /images/20230601/6466637bfb4145f2ae837c0a1dfc3ed3.png
[20190729161725.png]: /images/20230601/f339408b8e9f44d2b6831cdd2cbf30df.png