1.4 django restframework（中）

drf内置了很多便捷的功能，在接下来的课程中会给大家依次讲解下面的内容：

快速上手
请求的封装
版本管理
认证
权限
限流
序列化
视图
条件搜索
分页
路由
解析器

6. 限流

限流，限制用户访问频率，例如：用户1分钟最多访问100次或者短信验证码一天每天可以发送50次，防止盗刷。

对于匿名用户，使用用户IP作为唯一标识。
对于登录用户，使用用户ID或名称作为唯一标识。

底层实现：维护一个字典 加再drf缓存中 需要配置
缓存={
    用户标识：[12:33,12:32,12:31,12:30,12:00,]    #  限制 1小时/5次 插入访问时间   时间戳 ：12:34   11:34  已经超出用户访问次数 不让再访问了  等最早那个时间过期了 就可以访问了
{

pip3 install django-redis
# settings.py
CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379",
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient",
            "PASSWORD": "qwe123",
        }
    }
}

CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379",
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient",
            "PASSWORD": "qwe123",
        }
    }
}
# urls.py
from django.urls import path, re_path
from app01 import views

urlpatterns = [
    path('api/order/', views.OrderView.as_view()),
]
# views.py

from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import exceptions
from rest_framework import status
from rest_framework.throttling import SimpleRateThrottle
from django.core.cache import cache as default_cache


class ThrottledException(exceptions.APIException):
    status_code = status.HTTP_429_TOO_MANY_REQUESTS
    default_code = 'throttled'


class MyRateThrottle(SimpleRateThrottle):
    # 限流类
    cache = default_cache  # 访问记录存放在django的缓存中（需设置缓存）
    scope = "user"  # 构造缓存中的key
    cache_format = 'throttle_%(scope)s_%(ident)s'

    # 设置访问频率，例如：1分钟允许访问10次
    # 其他：'s', 'sec', 'm', 'min', 'h', 'hour', 'd', 'day'
    THROTTLE_RATES = {"user": "10/m"}
    
    # 用来生成用户唯一标识
    def get_cache_key(self, request, view):
        if request.user:
            ident = request.user.pk  # 用户ID
        else:
            ident = self.get_ident(request)  # 获取请求用户IP（去request中找请求头）

        # throttle_u  id
        # throttle_user_11.11.11.11ser_2  ip
        return self.cache_format % {'scope': self.scope, 'ident': ident}

    def throttle_failure(self):
        wait = self.wait()
        detail = {
            "code": 1005,
            "data": "访问频率限制",
            'detail': "需等待{}s才能访问".format(int(wait))
        }
        raise ThrottledException(detail)


class OrderView(APIView):
    throttle_classes = [MyRateThrottle, ]

    def get(self, request):
        return Response({"code": 0, "data": "数据..."})

多个限流类

本质，每个限流的类中都有一个 allow_request 方法，此方法内部可以有三种情况：

返回True，表示当前限流类允许访问，继续执行后续的限流类。
返回False，表示当前限流类不允许访问，继续执行后续的限流类。所有的限流类执行完毕后，读取所有不允许的限流，并计算还需等待的时间。
抛出异常，表示当前限流类不允许访问，后续限流类不再执行。

全局配置

REST_FRAMEWORK = {
    "DEFAULT_THROTTLE_CLASSES":["xxx.xxx.xx.限流类", ],
    "DEFAULT_THROTTLE_RATES": {
        "user": "10/m",
        "xx":"100/h"
    }
}

底层源码实现：

# settings.py

...
CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379",
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient",
            "PASSWORD": "qwe123",
        }
    }
}
# urls.py

from django.urls import path, re_path, include
from app01 import views

urlpatterns = [
    path('api/order/', views.OrderView.as_view()),
]
# views.py

from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import exceptions
from rest_framework import status
from rest_framework.throttling import SimpleRateThrottle
from django.core.cache import cache as default_cache


class ThrottledException(exceptions.APIException):
    status_code = status.HTTP_429_TOO_MANY_REQUESTS
    default_code = 'throttled'


class MyRateThrottle(SimpleRateThrottle):
    cache = default_cache  # 访问记录存放在django的缓存中（需设置缓存）
    scope = "user"  # 构造缓存中的key
    cache_format = 'throttle_%(scope)s_%(ident)s'

    # 设置访问频率，例如：1分钟允许访问10次
    # 其他：'s', 'sec', 'm', 'min', 'h', 'hour', 'd', 'day'
    THROTTLE_RATES = {"user": "10/m"}

    def get_cache_key(self, request, view):
        if request.user:
            ident = request.user.pk  # 用户ID
        else:
            ident = self.get_ident(request)  # 获取用户IP
        return self.cache_format % {'scope': self.scope, 'ident': ident}


class OrderView(APIView):
    throttle_classes = [MyRateThrottle, ]

    def get(self, request):
        return Response({"code": 0, "data": "数据..."})

    def throttled(self, request, wait):
        detail = {
            "code": 1005,
            "data": "访问频率",
            'detail': "需等待{}s才能访问".format(int(wait))
        }
        raise ThrottledException(detail)

7. Serializer（*）开发接口最常用的组件

drf中为我们提供了Serializer，他主要有两大功能：

对请求数据校验（底层调用Django的Form和ModelForm）
对数据库查询到的对象进行序列化（转换成json格式）

7.1.数据校验

示例1：基于Serializer：（和django的from很像）

底层调用的还是django的from 对请求数据的格式验证 min_length=6........

看email 验证规则的django中导入的 Emailvalidatiors

email1 是通过EmailFiled 会自动验证

email2 可以自定义一个正则表达式自定义同一个类RegexValidator

email3 通过钩子函数用于验证某个字段

示例2：基于ModelSerializer：（基于于Modelfrom 对字段进行验证不用每个字段都自己写了省事了）

# models.py

from django.db import models


class Role(models.Model):
    """ 角色表 """
    title = models.CharField(verbose_name="名称", max_length=32)


class Department(models.Model):
    """ 部门表 """
    title = models.CharField(verbose_name="名称", max_length=32)


class UserInfo(models.Model):
    """ 用户表 """
    level_choices = ((1, "普通会员"), (2, "VIP"), (3, "SVIP"),)
    level = models.IntegerField(verbose_name="级别", choices=level_choices, default=1)

    username = models.CharField(verbose_name="用户名", max_length=32)
    password = models.CharField(verbose_name="密码", max_length=64)
    age = models.IntegerField(verbose_name="年龄", default=0)
    email = models.CharField(verbose_name="邮箱", max_length=64)
    token = models.CharField(verbose_name="TOKEN", max_length=64, null=True, blank=True)

    # 外键
    depart = models.ForeignKey(verbose_name="部门", to="Department", on_delete=models.CASCADE)
    
    # 多对多
    roles = models.ManyToManyField(verbose_name="角色", to="Role")

提示：save方法会返回新生成的数据对象。

示例3：基于ModelSerializer（含FK（外键）+M2M（多对多关系））：

将含FK（外键）+M2M（多对多关系）这两个的字段加入的话用户校验过程是一样的

提示：save方法会返回新生成的数据对象。

7.2 序列化

通过ORM从数据库获取到的 QuerySet 或对象均可以被序列化为 json 格式数据。

# models.py

from django.db import models


class Role(models.Model):
    """ 角色表 """
    title = models.CharField(verbose_name="名称", max_length=32)


class Department(models.Model):
    """ 部门表 """
    title = models.CharField(verbose_name="名称", max_length=32)


class UserInfo(models.Model):
    """ 用户表 """
    level_choices = ((1, "普通会员"), (2, "VIP"), (3, "SVIP"),)
    level = models.IntegerField(verbose_name="级别", choices=level_choices, default=1)

    username = models.CharField(verbose_name="用户名", max_length=32)
    password = models.CharField(verbose_name="密码", max_length=64)
    age = models.IntegerField(verbose_name="年龄", default=0)
    email = models.CharField(verbose_name="邮箱", max_length=64, null=True, blank=True)
    token = models.CharField(verbose_name="TOKEN", max_length=64, null=True, blank=True)

    depart = models.ForeignKey(verbose_name="部门", to="Department", on_delete=models.CASCADE, null=True, blank=True)
    roles = models.ManyToManyField(verbose_name="角色", to="Role")

示例1：序列化基本字段

# 切记， 如果从数据库获取的不是QuerySet对象，而是单一对象，例如：
data_object = modes.UserInfo.objects.filter(id=2).first()
ser = UserModelSerializer(instance=data_object,many=False)
print(ser.data)

示例2：自定义字段

用户表关联的外表字段获取中文名称：level_text字段和 depart字段 source内部执行.get_level_display() 获取中文名称主动跨表source

自定义字段 roles 和extra字段如何展示数据呢通过自定义钩子方法 get_roles和get_extra

示例3：序列化类的嵌套（FK 和 M2M）

depart 和 roles 字段

7.3 数据校验&序列化

上述示例均属于单一功能（要么校验，要么序列化），其实当我们编写一个序列化类既可以做数据校验，也可以做序列化，例如：

# models.py

from django.db import models


class Role(models.Model):
    """ 角色表 """
    title = models.CharField(verbose_name="名称", max_length=32)


class Department(models.Model):
    """ 部门表 """
    title = models.CharField(verbose_name="名称", max_length=32)


class UserInfo(models.Model):
    """ 用户表 """
    level_choices = ((1, "普通会员"), (2, "VIP"), (3, "SVIP"),)
    level = models.IntegerField(verbose_name="级别", choices=level_choices, default=1)

    username = models.CharField(verbose_name="用户名", max_length=32)
    password = models.CharField(verbose_name="密码", max_length=64)
    age = models.IntegerField(verbose_name="年龄", default=0)
    email = models.CharField(verbose_name="邮箱", max_length=64, null=True, blank=True)
    token = models.CharField(verbose_name="TOKEN", max_length=64, null=True, blank=True)

    depart = models.ForeignKey(verbose_name="部门", to="Department", on_delete=models.CASCADE, null=True, blank=True)
    roles = models.ManyToManyField(verbose_name="角色", to="Role")

# urls.py

from django.urls import path, re_path, include
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view()),
]

# views.py

from django.core.validators import EmailValidator
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import serializers

from app01 import models


class DepartModelSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.Department
        fields = ['id', "title"]
        extra_kwargs = {
            "id": {"read_only": False},  # 数据验证
            "title": {"read_only": True}  # 只做序列化
        }


class RoleModelSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.Role
        fields = ['id', "title"]
        extra_kwargs = {
            "id": {"read_only": False},  # 数据验证
            "title": {"read_only": True}  # 只做序列化
        }

        
# 通过write_only=True和read_only=True 来设置字段是否需要序列化和表单验证
class UserModelSerializer(serializers.ModelSerializer):
    # 调用底层django的from
    #  read_only=True只做展示 只有在序列化的时候 才会给用户返还回去 数据校验不用此字段不需要用户提交这个字段
    level_text = serializers.CharField(source="get_level_display", read_only=True)
   
    # 这两个字段存在 Serializer 类的嵌套，不是read_only，一定要自定义重写create和update方法，自定义新增和更新的逻辑。
    depart = DepartModelSerializer(many=False)
    roles = RoleModelSerializer(many=True)

    extra = serializers.SerializerMethodField(read_only=True)
    # write_only=True只有表单提交是需要验证 做序列化的时候不需要 需要pop剔除掉
    email2 = serializers.EmailField(write_only=True)
    
    
    # username、email、 这三个字段既是write_only=True又是read_only=True
    # 数据校验：username、email、email2、部门、角色信息
    class Meta:
        model = models.UserInfo
        fields = [
            "username", "age", "email", "level_text", "depart", "roles", "extra", "email2"
        ]
        extra_kwargs = {
            "age": {"read_only": True}, # age 也是不用再校验了
            "email": {"validators": [EmailValidator, ]},
        }

    def get_extra(self, obj):
        return 666

    def validate_username(self, value):
        # 钩子函数对usename进行验证
        return value

    # 新增加数据时
    def create(self, validated_data):
        """ 如果有嵌套的Serializer，在进行数据校验时，只有两种选择：
              1. 将嵌套的序列化设置成 read_only
              2. 自定义create和update方法，自定义新建和更新的逻辑
            注意：用户端提交数据的格式。
        """
        depart_id = validated_data.pop('depart')['id'] # 部门id拿到

        role_id_list = [ele['id'] for ele in validated_data.pop('roles')] # 角色id拿到

        # 新增用户表数据
        validated_data['depart_id'] = depart_id
        user_object = models.UserInfo.objects.create(**validated_data)

        # 在用户表和角色表的关联表中添加对应关系
        user_object.roles.add(*role_id_list)

        return user_object
    # 数据更新
    def update(self,instance,validated_data)
        pass
class UserView(APIView):
    """ 用户管理 """

    def get(self, request):
        """ 添加用户 """
        queryset = models.UserInfo.objects.all()
        ser = UserModelSerializer(instance=queryset, many=True)
        return Response({"code": 0, 'data': ser.data})

    def post(self, request):
        """ 添加用户 """
        ser = UserModelSerializer(data=request.data) # Serializer用户请求数据格式校验
        if not ser.is_valid():
            return Response({'code': 1006, 'data': ser.errors})

        ser.validated_data.pop('email2')

        instance = ser.save(age=18, password="123", depart_id=1)

        # 新增之后的一个对象（内部调用UserModelSerializer进行序列化）
        print(instance)
        # ser = UserModelSerializer(instance=instance, many=False)
        # ser.data

        return Response({'code': 0, 'data': ser.data})

底层源码实现：

序列化的底层源码实现有别于上述其他的组件，序列化器相关类的定义和执行都是在视图中被调用的，所以源码的分析过程可以分为：定义类、序列化、数据校验。

源码1：序列化过程

源码2：数据校验过程

8. 视图

8.1 APIView

View，django
APIView，drf，在请求到来时，新增了：免除csrf、请求封装、版本、认证、权限、限流的功能。

# 假如：
class GenericAPIView(APIView):
    pass # 10功能

class GenericViewSet(xxxx.View-2个功能, GenericAPIView):
    pass # 5功能能

class UserView(GenericViewSet):
    # 这里又多了17个功能
    def get(self,request):
        pass

APIView是drf中 “顶层” 的视图类，在他的内部主要实现drf基础的组件的使用，例如：版本、认证、权限、限流等。

# urls.py

from django.urls import path, re_path, include
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view()),
    path('api/users/<int:pk>/', views.UserDetailView.as_view()),
]
# views.py

from rest_framework.views import APIView
from rest_framework.response import Response

class UserView(APIView):
    
    # 认证、权限、限流等
    
    def get(self, request):
        # 业务逻辑：查看列表
        return Response({"code": 0, 'data': "..."})

    def post(self, request):
        # 业务逻辑：新建
        return Response({'code': 0, 'data': "..."})
    
class UserDetailView(APIView):
    
    # 认证、权限、限流等
        
    def get(self, request,pk):
        # 业务逻辑：查看某个数据的详细
        return Response({"code": 0, 'data': "..."})

    def put(self, request,pk):
        # 业务逻辑：全部修改
        return Response({'code': 0, 'data': "..."})
    
    def patch(self, request,pk):
        # 业务逻辑：局部修改
        return Response({'code': 0, 'data': "..."})
    
    def delete(self, request,pk):
        # 业务逻辑：删除
        return Response({'code': 0, 'data': "..."})

8.2 GenericAPIView(中间人我们不会用它写代码)

GenericAPIView 继承APIView，在APIView的基础上又增加了一些功能。例如：get_queryset、get_object等。

实际在开发中一般不会直接继承它，他更多的是担任 中间人的角色，为子类提供公共功能。

# urls.py

from django.urls import path, re_path, include
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view()),
    path('api/users/<int:pk>/', views.UserDetailView.as_view()),
]
# views.py

from rest_framework.generics import GenericAPIView
from rest_framework.response import Response

# 序列化类
class MySerializers(serializers.ModelSerializer):
    class Meta:
        model = models.UserInfo
        fields = ['id','username']

class UserView(GenericAPIView):
　　# 数据库查询语句
    queryset = models.UserInfo.objects.filter(status=True)
    serializer_class =  MySerializers  # 序列化类
    
    # 用户提交get请求就会执行这个get方法
    def get(self, request):
        # 想要用self.get_queryset()方法获取数据库中的数据（读取类变量的queryset字段）
        queryset = self.get_queryset() 
        # get_serializer 获取Serialezer类并实例化（获取类变量中的serializer_class字段并实例化）
        # ser = MySerializers(intance=queryset,many=True)
        ser = self.get_serializer(intance=queryset,many=True)
        print(ser.data)
        return Response({"code": 0, 'data': "..."})

注意：`GenericAPIView 最大的意义，将数据库查询、序列化类提取到类变量中，后期再提供公共的get/post/put/delete等方法，让开发者只定义类变量，自动实现增删改查。

8.3 GenericViewSet（开发中很少继承它也属于中间人）

GenericViewSet类中没有定义任何代码，他就是继承 ViewSetMixin 和 GenericAPIView，也就说他的功能就是将继承的两个类的功能继承到一起。

GenericAPIView，将数据库查询、序列化类的定义提取到类变量中，便于后期处理。
ViewSetMixin，将 get/post/put/delete 等方法映射到 list、create、retrieve、update、partial_update、destroy方法中，让视图不再需要两个类。

# urls.py

from django.urls import path, re_path, include
from app01 import views

urlpatterns = [
    # get post 
    path('api/users/', views.UserView.as_view({"get":"list","post":"create"})),
    # get delete put path 这个加入了具体的id
    path('api/users/<int:pk>/', views.UserView.as_view({"get":"retrieve","put":"update","patch":"partial_update","delete":"destory"})),
]
# views.py

from rest_framework.viewsets import GenericViewSet
from rest_framework.response import Response

    
class UserView(GenericViewSet):
    
    # 认证、权限、限流等
    queryset = models.UserInfo.objects.filter(status=True)
    serializer_class = 序列化类
    
    def list(self, request):
        # 业务逻辑：查看列表
        queryset = self.get_queryset()
        ser = self.get_serializer(intance=queryset,many=True)
        print(ser.data)
        return Response({"code": 0, 'data': "..."})

    def create(self, request):
        # 业务逻辑：新建
        return Response({'code': 0, 'data': "..."})
    
    def retrieve(self, request,pk):
        # 业务逻辑：查看某个数据的详细
        return Response({"code": 0, 'data': "..."})

    def update(self, request,pk):
        # 业务逻辑：全部修改
        return Response({'code': 0, 'data': "..."})
    
    def partial_update(self, request,pk):
        # 业务逻辑：局部修改
        return Response({'code': 0, 'data': "..."})
    
    def destory(self, request,pk):
        # 业务逻辑：删除
        return Response({'code': 0, 'data': "..."})

注意：开发中一般也很少直接去继承他，因为他也属于是 中间人类，在原来 GenericAPIView 基础上又增加了一个映射而已。

8.4 五大类（常见视图类）

在drf的为我们提供好了5个用于做增、删、改（含局部修改）、查列表、查单个数据的5个类（需结合 GenericViewSet 使用）。

# urls.py

from django.urls import path, re_path, include
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view({"get":"list","post":"create"})),
    path('api/users/<int:pk>/', views.UserView.as_view({"get":"retrieve","put":"update","patch":"partial_update","delete":"destroy"})),
]
# views.py

from rest_framework.viewsets import GenericViewSet
# 5个类中已帮 写好了 `list`、`create`、`retrieve`、`update`、`partial_update`、`destory` 方法，
from rest_framework.mixins import (
    ListModelMixin, CreateModelMixin, RetrieveModelMixin, UpdateModelMixin,
    DestroyModelMixin, ListModelMixin
)

class UserView(CreateModelMixin,RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin,ListModelMixin,GenericViewSet):
    
    # 认证、权限、限流等
    queryset = models.UserInfo.objects.filter(status=True)
    serializer_class = 序列化类

在这个5个类中已帮我们写好了 list、create、retrieve、update、partial_update、destory 方法，我们只需要在根据写类变量：queryset、serializer_class即可。

示例1：

# urls.py

from django.urls import path
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view({"get": "list"})),
    path('api/users/<int:pk>/', views.UserView.as_view({"get": "retrieve"})),
]
# views.py

from rest_framework import serializers
from rest_framework.viewsets import GenericViewSet
from rest_framework import mixins
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["username", "age", "email", "level_text", "extra"]

    def get_extra(self, obj):
        return 666


class UserView(mixins.ListModelMixin, mixins.RetrieveModelMixin, GenericViewSet):
    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

示例2：

# urls.py

from django.urls import path
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view({"get": "list", "post": "create"})),
    path('api/users/<int:pk>/', views.UserView.as_view({"get": "retrieve"})),
]
# views.py

from rest_framework import serializers
from rest_framework.viewsets import GenericViewSet
from rest_framework import mixins
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["username", "age", "email", "level_text", "extra"]

    def get_extra(self, obj):
        return 666


class UserView(mixins.CreateModelMixin, GenericViewSet):
    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer
    
    # 重写里此方法会调用这个save 可以自定义里参数里面的值（钩子自定义）
    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

示例3：

# urls.py

from django.urls import path
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view(
        {"get": "list", "post": "create"}
    )),
    path('api/users/<int:pk>/', views.UserView.as_view(
        {"get": "retrieve", "put": "update", "patch": "partial_update", "delete": "destroy"}
    )),
]

# views.py

from rest_framework import serializers
from rest_framework.viewsets import GenericViewSet
from rest_framework import mixins
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["username", "age", "email", "level_text", "extra"]

    def get_extra(self, obj):
        return 666
class UserModelSerializer2(serializers.ModelSerializer):
    pass
# put请求 全部更新
# patch请求 局部更新
class UserView(mixins.ListModelMixin,
               mixins.RetrieveModelMixin,
               mixins.CreateModelMixin,
               mixins.UpdateModelMixin,
               mixins.DestroyModelMixin,
               GenericViewSet):
    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer
    # 添加
    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")
    # 重写get_serializer_class 根据请求方式的不同可以使用不同的序列化类
    def get_serializer_class(self):
        if self.request.method == 'POST':
            return UserModelSerializer
        return UserModelSerializer2
    
    
    def perform_update(self, serializer):
        serializer.save()
        
    def perform_destroy(self, instance):
        instance.delete()

示例4：

# urls.py

from django.urls import path
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view(
        {"get": "list", "post": "create"}
    )),
    path('api/users/<int:pk>/', views.UserView.as_view(
        {"get": "retrieve", "put": "update", "patch": "partial_update", "delete": "destroy"}
    )),
]

# views.py
from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["username", "age", "email", "level_text", "extra"]

    def get_extra(self, obj):
        return 666


class UserView(ModelViewSet):
    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

在开发过程中使用 五大类 或 ModelViewSet 是比较常见的，并且如果他们内部的某些功能不够用，还可以进行重新某些方法进行扩展。

问题：drf中提供了这么多视图，以后那个用的比较多？

接口与数据库操作无关，直接继承APIView
接口背后需要对数据库进行操作，一般：ModelViewSet 或 CreateModelMixin、ListModelMixin...
```
- 利用钩子自定义功能。
- 重写某个写方法，实现更加完善的功能。
```
根据自己公司的习惯，自定义：ModelViewSet 或 CreateModelMixin、ListModelMixin...

补充：权限

在之前定义权限类时，类中可以定义两个方法：has_permission 和 has_object_permission

has_permission ，在请求进入视图之前就会执行。
has_object_permission，当视图中调用 self.get_object时就会被调用（删除、更新、查看某个对象时都会调用），一般用于检查对某个对象是否具有权限进行操作。

class PermissionA(BasePermission):
    message = {"code": 1003, 'data': "无权访问"}
    
    def has_permission(self, request, view):
        exists = request.user.roles.filter(title="员工").exists()
        if exists:
            return True
        return False
    # 单条详情、删除、更新+局部更新，根据ID获取这条数据，当前用户是否有权限访问
    # 列表和添加页面不会执行
    def has_object_permission(self, request, view, obj):
        # 当前用户是否有权限访问此对象
        return True

所以，让我们在编写视图类时，如果是直接获取间接继承了 GenericAPIView，同时内部调用 get_object方法，这样在权限中通过 has_object_permission 就可以进行权限的处理。

9. 条件搜索/查询

如果某个API需要传递一些条件进行搜索，其实就在是URL后面通过GET传参即可，例如：

/api/users?age=19&category=12

在drf中也有相应组件可以支持条件搜索。

9.1 自定义Filter

# urls.py

from django.urls import path
from app01 import views

urlpatterns = [
    path('api/users/', views.UserView.as_view(
        {"get": "list", "post": "create"}
    )),
    path('api/users/<int:pk>/', views.UserView.as_view(
        {"get": "retrieve", "put": "update", "patch": "partial_update", "delete": "destroy"}
    )),
]
# views.py

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from rest_framework.filters import BaseFilterBackend
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["username", "age", "email", "level_text", "extra"]

    def get_extra(self, obj):
        return 666


class Filter1(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        age = request.query_params.get('age')
        if not age:
            return queryset
        return queryset.filter(age=age)


class Filter2(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        user_id = request.query_params.get('id')
        if not user_id:
            return queryset
        return queryset.filter(id__gt=user_id)


class UserView(ModelViewSet):
    filter_backends = [Filter1, Filter2] # 列表里存了两个类

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

9.2 第三方Filter（用的比价多）

https://cloud.tencent.com/developer/article/1744982

在drf开发中有一个常用的第三方过滤器：DjangoFilterBackend。

pip install django-filter

注册app：

INSTALLED_APPS = [
    ...
    'django_filters',
    ...
]

视图配置和应用（示例1）最简单的应用：

# views.py
from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from django_filters.rest_framework import DjangoFilterBackend
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["username", "age", "email", "level_text", "extra"]

    def get_extra(self, obj):
        return 666


class UserView(ModelViewSet):
    filter_backends = [DjangoFilterBackend, ]
    filterset_fields = ["id", "age", "email"]

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

视图配置和应用（示例2）复杂的搜索定义一个类对搜索条件配置：

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from django_filters.rest_framework import DjangoFilterBackend
from django_filters import FilterSet, filters
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    depart_title = serializers.CharField(
        source="depart.title",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["id", "username", "age", "email", "level_text", "extra", "depart_title"]

    def get_extra(self, obj):
        return 666


class MyFilterSet(FilterSet):
    # 除了数据库中的字段 还可以自定义一些字段 进行搜索
    depart = filters.CharFilter(field_name="depart__title", lookup_expr="exact")
    # field_name="depart__title"数据库跨表双下划线  （exact  =）
    min_id = filters.NumberFilter(field_name='id', lookup_expr='gte')
    # field_name='id'数据库id  (gte >=)

    class Meta:
        model = models.UserInfo
        fields = ["min_id", "depart"]
    # xxxxxx?min_id=3  [id>=3]
    # xxxxxx?depart=it  [depart__title='it']

class UserView(ModelViewSet):
    filter_backends = [DjangoFilterBackend, ]
    filterset_class = MyFilterSet

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

视图配置和应用（示例3）更复杂搜索条件：

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from django_filters.rest_framework import DjangoFilterBackend, OrderingFilter
from django_filters import FilterSet, filters
from app01 import models


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    depart_title = serializers.CharField(
        source="depart.title",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["id", "username", "age", "email", "level_text", "extra", "depart_title"]

    def get_extra(self, obj):
        return 666


class MyFilterSet(FilterSet):
    # 配置搜索条件的类
    # /api/users/?min_id=2  -> id>=2
    min_id = filters.NumberFilter(field_name='id', lookup_expr='gte')

    # /api/users/?name=wupeiqi  -> not ( username=wupeiqi )
    name = filters.CharFilter(field_name="username", lookup_expr="exact", exclude=True)

    # /api/users/?depart=xx     -> depart__title like %xx%
    depart = filters.CharFilter(field_name="depart__title", lookup_expr="contains")

    # /api/users/?token=true      -> "token" IS NULL
    # /api/users/?token=false     -> "token" IS NOT NULL
    token = filters.BooleanFilter(field_name="token", lookup_expr="isnull")

    # /api/users/?email=xx     -> email like xx%
    email = filters.CharFilter(field_name="email", lookup_expr="startswith")

    # /api/users/?level=2&level=1   -> "level" = 1 OR "level" = 2（必须的是存在的数据，否则报错-->内部有校验机制）
    # level = filters.AllValuesMultipleFilter(field_name="level", lookup_expr="exact")
    level = filters.MultipleChoiceFilter(field_name="level", lookup_expr="exact", choices=models.UserInfo.level_choices)

    # /api/users/?age=18,20     -> age in [18,20]
    age = filters.BaseInFilter(field_name='age', lookup_expr="in")

    # /api/users/?range_id_max=10&range_id_min=1    -> id BETWEEN 1 AND 10
    range_id = filters.NumericRangeFilter(field_name='id', lookup_expr='range')

    # /api/users/?ordering=id     -> order by id asc
    # /api/users/?ordering=-id     -> order by id desc 倒序
    # /api/users/?ordering=age     -> order by age asc
    # /api/users/?ordering=-age     -> order by age desc
    ordering = filters.OrderingFilter(fields=["id", "age"]) # 排序
    
    # 以上的差不多够用了 还可以自定义
    # /api/users/?size=1     -> limit 1（自定义搜索）
    # method='filter_size' 自定义方法filter_size 进行筛选
    size = filters.CharFilter(method='filter_size', distinct=False, required=False)
    
    class Meta:
        model = models.UserInfo
        fields = ["id", "min_id", "name", "depart", "email", "level", "age", 'range_id', "size", "ordering"]

    def filter_size(self, queryset, name, value):
        int_value = int(value)
        return queryset[0:int_value]


class UserView(ModelViewSet):
    filter_backends = [DjangoFilterBackend, ]
    filterset_class = MyFilterSet

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

lookup_expr有很多常见选择：

'exact': _(''), 大小写敏感
'iexact': _(''), 不敏感

'contains': _('contains'), 包含
'icontains': _('contains'),
'startswith': _('starts with'), 以什么开头
'istartswith': _('starts with'),
'endswith': _('ends with'),  
'iendswith': _('ends with'),
    
'gt': _('is greater than'), 
'gte': _('is greater than or equal to'),
'lt': _('is less than'),
'lte': _('is less than or equal to'),

'in': _('is in'),
'range': _('is in range'), 
'isnull': _(''),
    
'regex': _('matches regex'), 正则表达式 开发一般不会用正则 效率低
'iregex': _('matches regex'),

全局配置和应用：（适合通用的搜索每个视图都可以用）

# settings.py 全局配置

REST_FRAMEWORK = {
    'DEFAULT_FILTER_BACKENDS': ['django_filters.rest_framework.DjangoFilterBackend',]
}

class UserView(ModelViewSet):
    filter_backends = [DjangoFilterBackend, ]
    filterset_fields = ["id", "age", "email"] # 这个就是配置

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

9.3 内置Filter（基本不用）

drf源码中内置了2个filter，分别是：

OrderingFilter，支持排序。

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from app01 import models
from rest_framework.filters import OrderingFilter


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    depart_title = serializers.CharField(
        source="depart.title",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["id", "username", "age", "email", "level_text", "extra", "depart_title"]

    def get_extra(self, obj):
        return 666


class UserView(ModelViewSet):
    filter_backends = [OrderingFilter, ]
    # ?order=id
    # ?order=-id
    # ?order=age
    ordering_fields = ["id", "age"]

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

SearchFilter，支持模糊搜索。

from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from app01 import models
from rest_framework.filters import SearchFilter


class UserModelSerializer(serializers.ModelSerializer):
    level_text = serializers.CharField(
        source="get_level_display",
        read_only=True
    )
    depart_title = serializers.CharField(
        source="depart.title",
        read_only=True
    )
    extra = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = models.UserInfo
        fields = ["id", "username", "age", "email", "level_text", "extra", "depart_title"]

    def get_extra(self, obj):
        return 666


class UserView(ModelViewSet):
    # ?search=武沛%齐
    filter_backends = [SearchFilter, ]
    search_fields = ["id", "username", "age"]

    queryset = models.UserInfo.objects.all()
    serializer_class = UserModelSerializer

    def perform_create(self, serializer):
        """ 序列化：对请求的数据校验成功后，执行保存。"""
        serializer.save(depart_id=1, password="123")

"app01_userinfo"."id" LIKE %武沛齐% ESCAPE '\' 
OR 
"app01_userinfo"."username" LIKE %武沛齐% ESCAPE '\' 
OR 
"app01_userinfo"."age" LIKE %武沛齐% ESCAPE '\'

posted @ 2022-06-19 23:06 贰号猿阅读(138) 评论(0) 收藏举报

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1.4 django restframework（中）