Django 之 DRF-CBV (基于类的视图)

发表于 2021-12-20 更新于 2024-03-17 分类于 Python > Python教程 > Django 4.x 本文字数： 12k 阅读时长 ≈ 20 分钟

简介

FBV（function base views） 基于函数的视图，就是在视图里使用函数处理请求。
CBV（class base views） 基于类的视图，就是在视图里使用类处理请求。

CBV

views.py

from django.http import HttpResponse
from django.views import View
from django.shortcuts import render

from user.models import User


# Create your views here.
class RegisterView(View):
    def get(self, request):
        return render(request, 'register.html')

    def post(self, request):
        username = request.POST.get('username')
        password = request.POST.get('password')
        repassword = request.POST.get('repassword')
        if password == repassword:
            if user := User.objects.create(username=username, password=password):
                return HttpResponse(f'{user}注册成功！')
        return HttpResponse('注册失败')

register.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册</title>
</head>
<body>
<h1>注册</h1>
<form action="{% url 'register' %}" method="post">
    {% csrf_token %}
    <p><input type="text" name="username" placeholder="username"></p>
    <p><input type="password" name="password" placeholder="password"></p>
    <p><input type="password" name="repassword" placeholder="password"></p>
    <p><input type="submit" value="注册"></p>
</form>
</body>
</html>

urls.py

"""RESTful URL Configuration

The `urlpatterns` list routes URLs to views. For more information please see:
    https://docs.djangoproject.com/en/3.2/topics/http/urls/
Examples:
Function views
    1. Add an import:  from my_app import views
    2. Add a URL to urlpatterns:  path('', views.home, name='home')
Class-based views
    1. Add an import:  from other_app.views import Home
    2. Add a URL to urlpatterns:  path('', Home.as_view(), name='home')
Including another URLconf
    1. Import the include() function: from django.urls import include, path
    2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
"""
from django.contrib import admin
from django.urls import path

from user.views import RegisterView

urlpatterns = [
    path('admin/', admin.site.urls),
    path('register', RegisterView.as_view(), name='register')
]

CBV-Api

原生实现 (View)

views.py

from django.http import JsonResponse
from django.views import View
from django.shortcuts import render

from user.models import User


# Create your views here.
class UserView(View):
    def get(self, request, uid):
        user = User.objects.get(pk=uid)
        return JsonResponse({'status': 200, 'user': user.to_dict()})

    def post(self, request, uid):
        username = request.POST.get('username')
        password = request.POST.get('password')
        repassword = request.POST.get('repassword')
        if password == repassword:
            if User.objects.create(username=username, password=password):
                return JsonResponse({'status': 200, 'msg': '注册成功'})
        return JsonResponse({'status': 200, 'msg': '注册失败'})

models.py

from django.db import models


# Create your models here.
class User(models.Model):
    username = models.CharField(max_length=20, unique=True, verbose_name='用户名')
    password = models.CharField(max_length=20, verbose_name='密码')

    class Meta:
        db_table = 'user'
        verbose_name = '用户表'
        verbose_name_plural = verbose_name

    def __str__(self):
        return self.username

    # 手动序列化
    def to_dict(self):
        return {'id': self.id, 'username': self.username, 'password': self.password}

urls.py

"""RESTful URL Configuration

The `urlpatterns` list routes URLs to views. For more information please see:
    https://docs.djangoproject.com/en/3.2/topics/http/urls/
Examples:
Function views
    1. Add an import:  from my_app import views
    2. Add a URL to urlpatterns:  path('', views.home, name='home')
Class-based views
    1. Add an import:  from other_app.views import Home
    2. Add a URL to urlpatterns:  path('', Home.as_view(), name='home')
Including another URLconf
    1. Import the include() function: from django.urls import include, path
    2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
"""
from django.contrib import admin
from django.urls import path

from user.views import RegisterView, UserView

urlpatterns = [
    path('admin/', admin.site.urls),
    path('user/<int:uid>', UserView.as_view(), name='user')
]

序列化

简介
- 序列化：对象 ---> IO 中传输的格式
- 反序列化：IO 中传输的格式 ---> 对象
注意事项
- 如果想使用序列化和 APIView，必须安装：
  1
  pip install djangorestframework
- 然后将 rest_framework 添加到 settings.py 中的 INSTALLED_APPS 里，如下：
  1
  2
  3
  4
  5
  INSTALLED_APPS = [
  ...
  'user.apps.UserConfig',
  'rest_framework',
  ]

创建模型 (`models.py`)

from django.db import models


# Create your models here.
class User(models.Model):
    username = models.CharField(max_length=20, unique=True)
    password = models.CharField(max_length=128)
    phone = models.CharField(max_length=11)
    add_time = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = 'user'

    def __str__(self):
        return self.username

原生序列化

在应用目录下创建名为 serializers.py 文件

from rest_framework import serializers

from user.models import User


class UserSerializer(serializers.Serializer):
    # 定义需要序列化的字段
    id = serializers.IntegerField(read_only=True)
    username = serializers.CharField(max_length=20, min_length=5, required=True)
    password = serializers.CharField(max_length=128, required=True)
    phone = serializers.CharField(max_length=11, min_length=11)

使用序列化类：views.py

from django.contrib.auth.hashers import make_password
from django.shortcuts import render
from rest_framework.views import APIView
from django.http import JsonResponse

from user.serializers import UserSerializer
from user.models import User


# Create your views here.
class UserViews(APIView):
    def get(self, request):
        pass

    def post(self, request):
        # 获取POST中的值
        username = request.POST.get('username')
        password = request.POST.get('password')
        phone = request.POST.get('phone')
        password = make_password(password)
        # 构建对象
        user = User.objects.create(username=username, password=password, phone=phone)
        # 将对象传递给UserSerializer
        us = UserSerializer(user)
        # 获取序列化后的数据：us.data
        # print(us.data)
        return JsonResponse({'status': 200, 'user': us.data})

使用 ModelSerializers 序列化

serializers.py

class UserSerializer1(serializers.ModelSerializer):
    repassword = serializers.CharField(max_length=128, write_only=True)

    class Meta:
        model = User
        fields = ['id', 'username', 'password', 'phone', 'repassword']

    def validate(self, attrs):  # attrs 就是一个提交数据的字典形式
        if attrs['password'] != attrs['repassword']:
            attrs['flag'] = False
        return attrs

    def create(self, validated_data):
        username = validated_data['username']
        password = validated_data['password']
        phone = validated_data['phone']
        # 密码加密
        password = make_password(password)

        user = User.objects.create(username=username, password=password, phone=phone)

        return user

定制校验

定制具体字段的校验

class UserSerializer1(serializers.ModelSerializer):
    ......
    
    def validate_email(self, mail):
        if re.match(r'', email):
            return email
        else:
            raise serializers.ValidationError('邮箱错误')

定制全局校验

class UserSerializer1(serializers.ModelSerializer):
    ......   
    
    def validate(self, attrs):  # attrs 就是一个提交数据的字典形式
        if attrs['password'] != attrs['repassword']:
            attrs['flag'] = False
        return attrs

定制 create 方法：重写父类的 create 方法

class UserSerializer1(serializers.ModelSerializer):
    ......     
    
    def create(self, validated_data):
        username = validated_data['username']
        password = validated_data['password']
        phone = validated_data['phone']
        # 密码加密
        password = make_password(password)

        user = User.objects.create(username=username, password=password, phone=phone)

        return user

ModelSerializer 之 read_only 和 write_only
- write_only
  - 某个字段不属于指定 model，它是 write_only，需要用户传进来，但我们不能对它进行 save()，因为 ModelSerializer 是基于 Model，这个字段在 Model 中没有对应，这个时候，我们需要重写 validate() 方法！
  - 就是用户 post 过来的数据，后台服务器处理后不会再经过序列化后返回给客户端；最常见的就是我们在使用手机注册的验证码和填写的密码。
- read_only
  - 某个字段属于指定 model，它是 read_only，表示不允许用户自己上传，只能用于 api 的输出。
  - 如果某个字段设置了 read_only=True，那么就不需要进行数据验证，只会在返回时，将这个字段序列化后返回。
  - 举个简单的例子：在用户进行购物的时候，用户 post 订单时，肯定会产生一个订单号，而这个订单号应该由后台逻辑完成，而不应该由用户 post 过来，如果不设置 read_only=True，那么验证的时候就会报错。
  - 再例如，我们在网上购物时，支付时通常会产生支付状态，交易号、订单号、支付时间等字段，这些字段都应该设置为 read_only=True，即这些字段都应该由后台产生然后返回给客户端。

views.py

from django.http import JsonResponse
from rest_framework.views import APIView

from user.serializers import UserSerializer1


class UserViews1(APIView):
    def get(self, request):
        pass

    def post(self, request):
        # 只有在APIView中才能使用request.data   data = JSONParser().parse(request)
        us = UserSerializer1(data=request.data)
        if us.is_valid():  # 验证
            us.save()  # 保存
            return JsonResponse({'status': 200, 'user': us.data})

关系模型序列化

models.py (一对多)

from django.db import models


# Create your models here.
# 一
class UserType(models.Model):
    name = models.CharField(max_length=20, unique=True)
    add_time = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = 'user_type'


# 多
class User(models.Model):
    username = models.CharField(max_length=20, unique=True)
    password = models.CharField(max_length=128)
    phone = models.CharField(max_length=11)
    add_time = models.DateTimeField(auto_now=True)
    usertype = models.ForeignKey(to=UserType, on_delete=models.CASCADE, related_name='users', null=True)

    class Meta:
        db_table = 'user'

    def __str__(self):
        return self.username

serializers.py

from rest_framework import serializers

from user.models import UserType


class UserTypeSerializer(serializers.ModelSerializer):
    # 此类型下的多个用户，名称必须要与models中的外键related_name保持一致
    # users = serializers.StringRelatedField(many=True) # 名称展示
    users = serializers.PrimaryKeyRelatedField(many=True, read_only=True)  # 主键展示

    class Meta:
        model = UserType
        # 自定义的字段需要添加到fields中：“users”
        fields = ['id', 'name', 'add_time', 'users']

views.py

from django.http import JsonResponse
from rest_framework.views import APIView

from user.serializers import UserTypeSerializer
from user.models import UserType


# Create your views here.
class UserTypeView(APIView):
    def get(self, request):
        usertypes = UserType.objects.all()
        # 只要序列化的是多的内容则必须添加many=True
        serializer = UserTypeSerializer(usertypes, many=True)
        data = {
            'status': 200,
            'types': serializer.data
        }
        return JsonResponse(data)

反序列化

# 序列化
# 1. 将模型实例转换为Python原生数据类型
us = UserSerializer(user)
# 2. 将数据转换成json
content = JSONRenderer().render(us.data)

# 反序列化
# 1. 将一个流(stream)解析为Python原生数据类型
import io
stream = io.BytesIO(content)
data = JSONParser().parse(stream)
# 2. 然后我们要将Python原生数据类型恢复成正常的对象实例
us = UserSerializer(data=data)
us.is_valid()
us.validated_data
us.save()

Generic views

serializers.py

from rest_framework import serializers

from user.models import User


class SingleUserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ['id', 'username', 'password', 'phone', 'usertype']

views.py

from rest_framework.generics import ListCreateAPIView, RetrieveUpdateDestroyAPIView

from user.models import User
from user.serializers import SingleUserSerializer


class UserResource(ListCreateAPIView):
    # 操作的模型
    queryset = User.objects.all()
    # 此模型对应的序列化类
    serializer_class = SingleUserSerializer


class UserResource1(RetrieveUpdateDestroyAPIView):
    queryset = User.objects.all()
    serializer_class = SingleUserSerializer

urls.py

from django.urls import path, include

from user.views import UserResource, UserResource1

app_name = 'user'

urlpatterns = [
    path('single', UserResource.as_view(), name='single'),
    path('single1/<int:pk>', UserResource1.as_view(), name='single1'),
]

ViewSets

views.py

from rest_framework.viewsets import ModelViewSet

from user.models import User
from user.serializers import SingleUserSerializer


class UserResource2(ModelViewSet):
    queryset = User.objects.all()
    serializer_class = SingleUserSerializer

urls.py

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

from user.views import UserResource2

app_name = 'user'

router = DefaultRouter()
router.register(r'single', UserResource2)

urlpatterns = [
    path('', include(router.urls))
]

简介

CBV

views.py

register.html

urls.py

CBV-Api

原生实现 (View)

views.py

models.py

urls.py

序列化

简介

注意事项

创建模型 (models.py)

原生序列化

使用 ModelSerializers 序列化

关系模型序列化

反序列化

Generic views

ViewSets

创建模型 (`models.py`)