drf序列化器与反序列化

Posted 2022-08-01 huanghongzheng

什么是序列化与反序列化

"""
序列化：对象转换为字符串用于传输
反序列化：字符串转换为对象用于使用
"""

drf序列化与反序列化

"""
序列化：Model类对象转换为字符串用于传输
反序列化：字符串转换为Model类对象用于使用
"""

Model类

创建数据库：终端

>: mysql -uroot -p密码
>: create database 数据库名 charset=utf8

配置数据库：settings.py

DATABASES = 
    'default': 
        'ENGINE': 'django.db.backends.mysql',
        'NAME': '数据库名',
        'USER': 'root',
        'PASSWORD': '密码'
    

修改操作数据库的模块：项目init文件

import pymysql
pymysql.install_as_MySQLdb()

创建model类：models.py

from django.db import models
class User(models.Model):
    CHOICE_SEX = (
        (0, '男'),
        (1, '女')
    )
    name = models.CharField(max_length=32, verbose_name='姓名')
    password = models.CharField(max_length=64, verbose_name='密码')
    sex = models.SmallIntegerField(choices=CHOICE_SEX, default=0)
    create_time = models.DateTimeField(auto_now_add=True, blank=True)

    class Meta:
        # 自定义创建的表名
        db_table = 'o_user'
        # admin界面中显示的表面与表名复数形式
        verbose_name = '用户'
        verbose_name_plural = verbose_name

    def __str__(self):
        return self.name

注册model类：admin.py

from django.contrib import admin
from api.models import User
admin.site.register(User)

数据库迁移：在项目目录下的终端

>: python3 manage.py makemigrations
>: python3 manage.py migrate

注册超级用户：在项目目录下的终端

>: python3 manage.py createsuperuser

登陆admin页面添加数据：浏览器

http://localhost:8000/admin/

路由分发

项目urls.py

from django.conf.urls import url, include
from django.contrib import admin

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

api应用urls.py

from django.conf.urls import url
urlpatterns = [

]

获取多资源 接口

序列化类：serializers.py

from rest_framework import serializers

# 为每一个Model类至少配一个Serializer类
class UserSerializer(serializers.Serializer):
    # 序列化一个Model类对象，其实就是序列化该类的每一个属性
    name = serializers.CharField()
    password = serializers.CharField()
    sex = serializers.IntegerField()
    create_time = serializers.DateTimeField()

视图类：views.py

from rest_framework.views import APIView
from rest_framework.response import Response
from .models import User
from .serializers import UserSerializer

# 对应路由：/users/
# 功能：get获取所有 | post新增一个 | put修改一个 | delete删除一个
class UsersAPIView(APIView):
    def get(self, request, *args, **kwargs):
        user_list = User.objects.all()
        
        # instance存放的是queryset对象，many需要设置为True
        user_data = UserSerializer(instance=user_list, many=True).data
        return Response(
            
                'status': 0,
                'msg': 'ok',
                'results': user_data
            
        )

序列化字段操作（自定义字段）

序列化类修订：serializers.py

from rest_framework import serializers

# 为每一个Model类至少配一个Serializer类
class UserSerializer(serializers.Serializer):
    # 序列化一个Model类对象，其实就是序列化该类的每一个属性
    # 注意1：Model类与Serializer类是通过属性名建立关联的 - 属性名必须依照
    name = serializers.CharField()
    password = serializers.CharField()
    # sex = serializers.IntegerField()
    # 注意2：不需要通过给前台的数据，不需要提供该属性的序列化
    # create_time = serializers.DateTimeField()

    # 注意3：serializers.SerializerMethodField()可以产生自定义序列化属性(不需要和Model类属性同步)，
    #       但要为其绑定一个提供值的函数，函数名为 get_属性(self, obj) (obj为参与序列化的Model类对象)
    gender = serializers.SerializerMethodField()
    def get_gender(self, obj):
        # 该函数的返回值就作为对应自定义数据序列化后的值
        return obj.get_sex_display()

新增单资源 接口

序列化类(反序列化类)：serializers.py

from rest_framework import serializers
from .models import User


class UserDeserializer(serializers.Serializer):
    name = serializers.CharField(label='姓名', max_length=32, min_length=3, error_messages=
        'max_length': '姓名太长',
        'min_length': '姓名太短'
    )
    password = serializers.CharField(label='密码', max_length=64, min_length=3, error_messages=
        'max_length': '密码太长',
        'min_length': '密码太短'
    )
    sex = serializers.IntegerField()
    # required=False该字段前台可以不用传(不参与校验)
    create_time = serializers.DateTimeField(required=False)

    # 完成ORM的操作
    # def save(self):  # 不能直接重写save，因为系统的save可以完成新增或修改
    #     # print(self.validated_data)
    #     User.objects.create(**self.validated_data)

    # 为post接口提供新增Model类对象的功能
    def create(self, validated_data):
        # 返回值：Model类要新增的对象
        return User.objects.create(**validated_data)

视图类：views.py

from rest_framework.views import APIView
from rest_framework.response import Response
from .models import User
from .serializers import UserSerializer

# 对应路由：/users/
# 功能：get获取所有 | post新增一个 | put修改一个 | delete删除一个
class UsersAPIView(APIView):
    # 新增一个资源
    def post(self, request, *args, **kwargs):
        user_deser = UserDeserializer(data=request.data)
        # raise_exception值为True，当校验失败，直接返回校验失败的错误信息
        # result = user_deser.is_valid(raise_exception=True)
        result = user_deser.is_valid()
        if result:
            new_user_obj = user_deser.save()
            return Response(
                'status': 0,
                'msg': 'success',
                'result': UserSerializer(new_user_obj).data
            )
        else:
            return Response(
                'status': 1,
                'msg': 'failed',
                'results': user_deser.errors
            )

更新单资源 接口

序列化类(反序列化类)：serializers.py

from rest_framework import serializers
from .models import User


class UserDeserializer(serializers.Serializer):
    name = serializers.CharField(label='姓名', max_length=32, min_length=3, error_messages=
        'max_length': '姓名太长',
        'min_length': '姓名太短'
    )
    password = serializers.CharField(label='密码', max_length=64, min_length=3, error_messages=
        'max_length': '密码太长',
        'min_length': '密码太短'
    )
    sex = serializers.IntegerField()
    # required=False该字段前台可以不用传(不参与校验)
    create_time = serializers.DateTimeField(required=False)

    # 完成ORM的操作
    # def save(self):  # 不能直接重写save，因为系统的save可以完成新增或修改
    #     # print(self.validated_data)
    #     User.objects.create(**self.validated_data)

    # 为post接口提供新增Model类对象的功能
    def create(self, validated_data):
        # 返回值：Model类要新增的对象
        return User.objects.create(**validated_data)
    
    # 为put接口提供更新Model类对象的功能
    def update(self, instance, validated_data):
        # 操作model对象
        # instance.name = validated_data.get('name')
        # instance.password = validated_data.get('password')
        # instance.sex = validated_data.get('sex')
        # instance.save()
        # 操作queryset对象
        instance.update(**validated_data)
        return instance

视图类：views.py

from rest_framework.views import APIView
from rest_framework.response import Response
from .models import User
from .serializers import UserSerializer

# 对应路由：/users/
# 功能：get获取所有 | post新增一个 | put修改一个 | delete删除一个
class UsersAPIView(APIView):
    # 更新一个资源
    def put(self, request, *args, **kwargs):
        # 要更新的资源的主键
        pk = kwargs.get('pk')
        
        # 操作更新时可以选择操作 queryset对象 或 model对象
        # 操作model对象
        # old_user_obj = User.objects.get(pk=pk)
        # user_deser = UserDeserializer(instance=old_user_obj, data=request.data)

        # 操作queryset对象
        old_user_query = User.objects.filter(pk=pk)
        user_deser = UserDeserializer(instance=old_user_query, data=request.data)

        # raise_exception值为True，当校验失败，直接返回校验失败的错误信息
        # result = user_deser.is_valid(raise_exception=True)
        result = user_deser.is_valid()
        if result:
            # new_user_obj = user_deser.save()  # 操作model对象
            new_user_query = user_deser.save()  # 操作queryset对象
            new_user_obj = new_user_query.first()
            return Response(
                'status': 0,
                'msg': 'success',
                'result': UserSerializer(new_user_obj).data
            )
        else:
            return Response(
                'status': 1,
                'msg': 'failed',
                'results': user_deser.errors
            )

删除单资源 接口

重构Model新增字段：models.py

class User(models.Model):
    CHOICE_SEX = (
        (0, '男'),
        (1, '女')
    )
    name = models.CharField(max_length=32, verbose_name='姓名')
    password = models.CharField(max_length=64, verbose_name='密码')
    sex = models.SmallIntegerField(choices=CHOICE_SEX, default=0)
    create_time = models.DateTimeField(auto_now_add=True, blank=True)
    # 新增：数据删除不是从数据库删除记录，而是修改记录状态，标示为已删除即可
    is_delete = models.BooleanField(default=False)

    class Meta:
        # 自定义创建的表名
        db_table = 'o_user'
        # admin界面中显示的表面与表名复数形式
        verbose_name = '用户'
        verbose_name_plural = verbose_name

    def __str__(self):
        return self.name

数据库迁移：在项目目录下的终端

>: python3 manage.py makemigrations
>: python3 manage.py migrate

视图类接口：views.py

from rest_framework.views import APIView
from rest_framework.response import Response
from .models import User
from .serializers import UserSerializer

# 对应路由：/users/
# 功能：get获取所有 | post新增一个 | put修改一个 | delete删除一个
class UsersAPIView(APIView):
    # 删除一个资源
    def delete(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        try:
            delete_user_obj = User.objects.get(pk=pk, is_delete=False)
            # 完成删除信息的更新
            delete_user_obj.is_delete = True
            delete_user_obj.save()
            return Response()
        except:
            return Response(
                'status': 1,
                'msg': '数据删除失败'
            )

获取单资源 接口

序列化类：serializers.py

from rest_framework import serializers

# 为每一个Model类至少配一个Serializer类
class UserSerializer(serializers.Serializer):
    # 序列化一个Model类对象，其实就是序列化该类的每一个属性
    name = serializers.CharField()
    password = serializers.CharField()
    sex = serializers.IntegerField()
    create_time = serializers.DateTimeField()

视图类：views.py

from rest_framework.views import APIView
from rest_framework.response import Response
from .models import User
from .serializers import UserSerializer

# 对应路由：/users/
# 功能：get获取所有 | post新增一个 | put修改一个 | delete删除一个
class UsersAPIView(APIView):
    def get(self, request, *args, **kwargs):
         pk = kwargs.get('pk', None)

        if not pk:
            user_query = User.objects.filter(is_delete=False).all()
        else:
            user_query = User.objects.filter(is_delete=False, pk=pk)
            # 如果只操作一个对象，many参数需要为False(默认值)
            # user_obj = User.objects.filter(is_delete=False, pk=pk).first()
            # user_data = UserSerializer(instance=user_obj, many=False).data

        user_data = UserSerializer(instance=user_query, many=True).data
        return Response(
            
                'status': 0,
                'msg': 'ok',
                'results': user_data
            
        )

序列化基础：重点内容

模型类：models.py

from django.db import models

# Create your models here.

class User(models.Model):
    CHOICE_SEX = (
        (0, '男'),
        (1, '女')
    )
    name = models.CharField(max_length=32, verbose_name='姓名')
    password = models.CharField(max_length=64, verbose_name='密码')
    sex = models.SmallIntegerField(choices=CHOICE_SEX, default=0)
    create_time = models.DateTimeField(auto_now_add=True, blank=True)
    # 数据删除不是从数据库删除记录，而是修改记录状态，标示为已删除即可
    is_delete = models.BooleanField(default=False)

    class Meta:
        # 自定义创建的表名
        db_table = 'o_user'
        # admin界面中显示的表面与表名复数形式
        verbose_name = '用户'
        verbose_name_plural = verbose_name

    def __str__(self):
        return self.name

序列化类：

from rest_framework import serializers
from .models import User

class UserSerializer(serializers.Serializer):
    # 序列化和反序列化都可以使用
    name = serializers.CharField(label='姓名', max_length=32, min_length=3, error_messages=
        'max_length': '姓名太长',
        'min_length': '姓名太短'
    )
    password = serializers.CharField(label='密码', max_length=64, min_length=3, error_messages=
        'max_length': '密码太长',
        'min_length': '密码太短'
    )
    # 只有反序列化使用 - 用 write_only=True 标示只参与反序列化
    sex = serializers.IntegerField(write_only=True)
    # 只有序列化使用 - 自定义字段 - 用 read_only=True 标示只参与序列化
    gender = serializers.SerializerMethodField(read_only=True)
    def get_gender(self, obj):
        return obj.get_sex_display()
    # 序列化与反序列化都不使用 - 1）注释 | 2）required=False, write_only=True
    create_time = serializers.DateTimeField(required=False, write_only=True)

    # 为全局校验钩子新增校验字段
    re_password = serializers.CharField(label='确认密码', max_length=64, min_length=3, write_only=True, error_messages=
        'max_length': '确认密码太长',
        'min_length': '确认密码太短'
    )


    # 反序列化两大方法重写 - 新增create | 更新update
    # 为post接口提供新增Model类对象的功能
    def create(self, validated_data):
        # 返回值：Model类要新增的对象
        return User.objects.create(**validated_data)

    # 为put接口提供更新Model类对象的功能
    def update(self, instance, validated_data):
        instance.update(**validated_data)
        # 返回更新后的instance
        return instance


    # 局部钩子
    def validate_sex(self, value):
        if value not in (0, 1):
            raise serializers.ValidationError('未知性别')
        return value

    # 全局钩子
    def validate(self, attrs):
        re_password = attrs.pop('re_password')
        password = attrs.get('password')
        if re_password != password:
            raise serializers.ValidationError('二次密码不一致')
        return attrs

视图类：

from rest_framework.views import APIView
from rest_framework.response import Response
from .models import User
from .serializers import UserSerializer

# 对应路由：/users/ | /users/pk/
# 功能：get获取所有 | post新增一个 | put修改一个 | delete删除一个 | get获取一个
class UsersAPIView(APIView):
    # 获取所有资源 | 单个资源
    def get(self, request, *args, **kwargs):
        # 单个资源的主键
        pk = kwargs.get('pk', None)
        if not pk:
            user_query = User.objects.filter(is_delete=False).all()
        else:
            user_query = User.objects.filter(is_delete=False, pk=pk)

        user_data = UserSerializer(instance=user_query, many=True).data
        return Response(
            
                'status': 0,
                'msg': 'ok',
                'results': user_data
            
        )

    # 新增一个资源
    def post(self, request, *args, **kwargs):
        user_deser = UserSerializer(data=request.data)

        # raise_exception值为True，当校验失败，直接返回校验失败的错误信息
        # result = user_deser.is_valid(raise_exception=True)
        result = user_deser.is_valid()
        if result:
            new_user_obj = user_deser.save()
            return Response(
                'status': 0,
                'msg': 'success',
                'result': UserSerializer(new_user_obj).data
            )
        else:
            return Response(
                'status': 1,
                'msg': 'failed',
                'results': user_deser.errors
            )

    # 更新一个资源
    def put(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        old_user_query = User.objects.filter(pk=pk, is_delete=False)
        # 没有数据
        if not old_user_query:
            return Response(
                'status': 1,
                'msg': 'update failed',
            )

        user_deser = UserSerializer(instance=old_user_query, data=request.data)
        result = user_deser.is_valid()
        if result:
            new_user_query = user_deser.save()
            new_user_obj = new_user_query.first()
            return Response(
                'status': 0,
                'msg': 'success',
                'result': UserSerializer(new_user_obj).data
            )
        else:
            return Response(
                'status': 1,
                'msg': 'failed',
                'results': user_deser.errors
            )

    # 删除一个资源
    def delete(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        try:
            delete_user_obj = User.objects.get(pk=pk, is_delete=False)
            # 完成删除信息的更新
            delete_user_obj.is_delete = True
            delete_user_obj.save()
            return Response()
        except:
            return Response(
                'status': 1,
                'msg': '数据删除失败'
            )