drf框架2-序列化与反序列化

二次封装Response

from rest_framework.response import Response
"""
# 封装前
Response({
    'status': 0,
    'msg': 'ok',
    'results': [],
    'token': ''
}, headers={}, status=200, content_type="")

# 封装后
APIResponse(0, 'ok', results, status, headers, content_type)
"""

class APIResponse(Response):
    def __init__(self, data_status, data_msg, results=None,
                 status=None, headers=None, content_type=None, **kwargs):
        data = {
            'status': data_status,
            'msg': data_msg
        }
        if results:
            data['results'] = results
        data.update(kwargs)
        super().__init__(data=data, status=status, headers=headers, content_type=content_type)

序列化组件

"""
序列化：对象 可以序列化后 用于网络传输
反序列化：网络传输来的数据 反序列化成 对象用于使用
"""

准备工作

路由

# 主路由 urls.py
from django.conf.urls import url, include
from django.contrib import admin
from django.views.static import serve
from django.conf import settings
urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^api/', include('api.urls')),

    url(r'^media/(?P<path>.*)', serve, {'document_root': settings.MEDIA_ROOT})
]

# 子路由 api/urls.py
from django.conf.urls import url
from . import views
urlpatterns = [
    url(r'^users/$', views.UserAPIView.as_view()),
    url(r'^users/(?P<pk>.*)/$', views.UserAPIView.as_view()),
]

模型：api/models.py

class User(models.Model):
    # choices的字段，直接获取只能获取 0 | 1 | 2
    # 想获取 值后 的映射关系 男 | 女 | 哇塞 用  get_字段名_display()
    # eg：user_obj.get_sex_diaplay()
    SEX_CHOICES = [
        (0, '男'),
        (1, '女'),
        (2, '哇塞')
    ]
    username = models.CharField(max_length=64, unique=True)
    password = models.CharField(max_length=64)
    sex = models.IntegerField(choices=SEX_CHOICES, default=0)
    icon = models.ImageField(upload_to='icon', default='icon/default.png')
    create_time = models.DateTimeField(auto_now_add=True, null=True)
    is_delete = models.BooleanField(default=False)

    class Meta:
        db_table = 'old_boy_user'
        verbose_name = '用户'
        verbose_name_plural = verbose_name

    def __str__(self):
        return self.username

配置：settings.py

# 注册
INSTALLED_APPS = [
    # ...
    'rest_framework',
]

# 国际化配置
LANGUAGE_CODE = 'zh-hans'
TIME_ZONE = 'Asia/Shanghai'
USE_I18N = True
USE_L10N = True
USE_TZ = False

# media资源配置
MEDIA_URL = '/media/'  # 序列化media文件夹下的资源，会默认添加MEDIA_URL
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

简单认识序列化

序列化类：api/serializers.py

from django.conf import settings
from . import models
# 序列化
class UserSerializer(serializers.Serializer):
    # 1）参与序列化的属性名必须与model类的属性字段名相同
    # 2）不需要序列化的属性字段在序列化类中不需要声明
    # 3) 方法序列化字段，不需要在model类中有字段属性对应，值来源于 get_字段 方法
    #       序列化字段可以完全自定义，也可以与model类中有字段属性相同

    # 1）
    username = serializers.CharField()
    # 2）
    # password = serializers.CharField()
    sex = serializers.IntegerField()
    # icon = serializers.ImageField()

    # 3)
    gender = serializers.SerializerMethodField()
    def get_gender(self, user_obj):
        return user_obj.get_sex_display()

    icon = serializers.SerializerMethodField()
    def get_icon(self, user_obj):
        icon_url = 'http://127.0.0.1:8000{}{}'.format(settings.MEDIA_URL, user_obj.icon)
        return icon_url

序列化视图类：api/views.py

from rest_framework.views import APIView
from utils_home.response import APIResponse
from . import models, serializers
class UserAPIView(APIView):
    # 序列化对象：
    # UserSerializer(序列化数据, many)
    # 1）序列化数据可以为User类的单个对象，many=False(默认，可以省略不写)
    # 2）序列化数据可以为状态User类的多个对象的单列集合
    #       [] () {} QuerySet，此时many=True必须明确
    def get(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:  # 获取单个资源
            user_obj = models.User.objects.filter(pk=pk).first()
            if not user_obj:
                return APIResponse(1, 'pk error')
            user_obj_data = serializers.UserSerializer(user_obj).data
            return APIResponse(0, 'ok', results=user_obj_data)

        # 获取多个资源
        user_query = models.User.objects.all()
        user_ser = serializers.UserSerializer(user_query, many=True)
        user_list_data = user_ser.data
        return APIResponse(0, 'get ok', results=user_list_data)

简单认识反序列化

反序列化类：api/serializers.py

from django.conf import settings
from . import models
# 反序列化
class UserDeserializer(serializers.Serializer):
    # 1）在字段类型后定义基础校验规则
    # 2）基础校验完毕，可以在局部钩子方法中进行单个字段校验规则的扩展
    # 3）在局部钩子校验完毕，在全局钩子中完成多个字段协同校验
    # 4）如果需要提供数据的增加功能，需要重写create方法，完成数据的入库

    # 1）默认校验
    username = serializers.CharField(
        min_length=3,
        error_messages={
            'min_length': '用户名太短'
        }
    )
    password = serializers.CharField(
        min_length=3,
        error_messages={
            'min_length': '密码太短'
        }
    )
    re_password = serializers.CharField(
        min_length=3,
        required=True,
        error_messages={
            'min_length': '确认密码太短',
            'required': '确认密码不能为空'
        }
    )

    # 有默认值的字段，前台可能提供，可能不通过，这样的字段用required=False处理
    sex = serializers.IntegerField(required=False)

    # 2）局部钩子: validate_字段名(self, 字段值)
    def validate_username(self, value):
        if 'sb' in value:
            raise serializers.ValidationError('用户名包含敏感词汇')
        return value

    # 3）全局钩子：validate(self, 所有字段值)
    def validate(self, attrs):
        print(attrs)
        password = attrs.get('password')
        # 校验通过后，要完成数据的增加，该增加不参与，要从数据们中剔除
        re_password = attrs.pop('re_password')
        if password != re_password:
            raise serializers.ValidationError({'re_password': '两次密码不一致'})
        return attrs

    # 4）完成model类对象的增加，必须重写create方法
    def create(self, validated_data):
        try:
            return models.User.objects.create(**validated_data)
        except:
            raise IOError('数据库入库失败')  # 数据库异常在异常模块中完善

序列化视图类：api/views.py

from rest_framework.views import APIView
from utils_home.response import APIResponse
from . import models, serializers
class UserAPIView(APIView):
    # 反序列化请求数据
    # UserDeserializer(data=反序列化数据, many=False)
    # 1）反序列化数据可以为单个数据字典，many=False或者不写
    # 2）反序列化数据可以为存放数据字典的单列集合，many=True必须明确（后面讲）
    # 3）反序列化数据必须赋值给data关键字参数，才能进行数据校验
    # 4）序列化对象.is_valid(raise_exception=True)校验失败会自动返回错误信息给前台
    # 5）if 序列化对象.is_valid(): 可以自定义校验成功与失败分支的返回结果
    #       成功可以完成新增或修改，失败错误信息在 序列化对象.errors 中

    def post(self, request, *args, **kwargs):
        request_data = request.data
        print(request_data)
        user_ser = serializers.UserDeserializer(data=request_data)
        # 自动返回错误信息
        # user_ser.is_valid(raise_exception=True)
        if user_ser.is_valid():  # 自定义处理校验成功的逻辑
            user_obj = user_ser.save()
            return APIResponse(0, 'ok',
                results=serializers.UserSerializer(user_obj).data
            )
        else:  # 自定义返回错误信息
            return APIResponse(1, 'failed', results=user_ser.errors)

序列化与反序列化共存（重点）

路由：api/urls.py

from django.conf.urls import url
from . import views
urlpatterns = [
    url(r'^users/$', views.UserAPIView.as_view()),
    url(r'^users/(?P<pk>.*)/$', views.UserAPIView.as_view()),
    # 整合序列化与反序列
    url(r'^v2/users/$', views.UserV2APIView.as_view()),
    url(r'^v2/users/(?P<pk>.*)/$', views.UserV2APIView.as_view()),
]

序列化层：api/serializers.py

from rest_framework import serializers
from django.conf import settings
from . import models
# 序列化与反序列化整合
class UserV2Serializer(serializers.Serializer):
    # 1）参与序列化与反序列化的字段(包括自定义字段)都必须明确
    # 2）通过 read_only=True 表明该字段只参与序列化
    # 3）通过 write_only=True 表明该字段只参与反序列化
    # 4）参与反序列化，但是是选填字段(前台可以提供或不提供)，用 required=False 处理
    # 5）要完成数据库增加，需要重写 create 方法
    # 6）要完成数据库更新，需要重写 update 方法
    
    username = serializers.CharField(min_length=3)
    # 只参与反序列化 write_only=True
    password = serializers.CharField(write_only=True, min_length=3)
    sex = serializers.IntegerField(write_only=True, required=False)
    re_password = serializers.CharField(write_only=True, min_length=3, required=True)
    # 只参与序列化 read_only=True
    gender = serializers.SerializerMethodField(read_only=True)
    def get_gender(self, user_obj):
        return user_obj.get_sex_display()
    icon = serializers.SerializerMethodField(read_only=True)
    def get_icon(self, user_obj):
        icon_url = 'http://127.0.0.1:8000{}{}'.format(settings.MEDIA_URL, user_obj.icon)
        return icon_url

    def validate_username(self, value):
        if 'sb' in value:
            raise serializers.ValidationError('用户名包含敏感词汇')
        return value

    def validate(self, attrs):
        print('序列化内：', self.context)
        password = attrs.get('password')
        re_password = attrs.get('re_password')
        if password:
            if re_password:
                attrs.pop('re_password')
                if password != re_password:
                    raise serializers.ValidationError({'re_password': '两次密码不一致'})
            else:
                raise serializers.ValidationError({'re_password': '密码必须确认'})
        return attrs

    # 增
    def create(self, validated_data):
        try:
            return models.User.objects.create(**validated_data)
        except:
            raise IOError('数据库入库失败')
    # 改
    def update(self, instance, validated_data):
        # instance：是自定义传入的要更新的原数据（pk | obj | queryset）
        # validated_data：是校验通过后的新数据

        # instance的值外部反序列化传入要更新的自定义标识决定
        instance.update(**validated_data)
        return instance.first()

视图层：api/views.py

from rest_framework.views import APIView
from utils_home.response import APIResponse
from . import models, serializers
class UserV2APIView(APIView):
    # 单取、群取
    def get(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:
            user_obj = models.User.objects.filter(pk=pk, is_delete=False).first()
            if not user_obj:
                return APIResponse(1, 'pk error')
            user_obj_data = serializers.UserV2Serializer(user_obj).data
            return APIResponse(0, 'ok', results=user_obj_data)

        user_query = models.User.objects.filter(is_delete=False).all()
        user_ser = serializers.UserV2Serializer(user_query, many=True)
        user_list_data = user_ser.data
        return APIResponse(0, 'ok', results=user_list_data)

    # 单增
    def post(self, request, *args, **kwargs):
        request_data = request.data
        print(request_data)
        user_ser = serializers.UserV2Serializer(data=request_data)
        if user_ser.is_valid():
            user_obj = user_ser.save()
            return APIResponse(0, 'ok',
                results=serializers.UserV2Serializer(user_obj).data
            )
        else:
            return APIResponse(1, 'failed', results=user_ser.errors)

    # 单整体改
    def put(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if not pk:
            return APIResponse(1, 'pk error')

        user_query = models.User.objects.filter(pk=pk, is_delete=False)
        if not user_query:
            return APIResponse(1, 'user error')

        # 第一种：user_query完成数据的更新
        # user_query = models.User.objects.filter(pk=pk)
        # user_query.update(**kwargs)

        # 第二种：user_obj完成数据的更新
        # user_obj = models.User.objects.filter(pk=pk).first()  # type: models.User
        # user_obj.username = 'new_username'
        # ...
        # user_obj.save()


        request_data = request.data
        user_ser = serializers.UserV2Serializer(instance=user_query, data=request_data)
        if user_ser.is_valid():
            # save的返回值是由update内部自定义的返回值决定
            user_obj = user_ser.save()
            return APIResponse(0, 'ok',
                results=serializers.UserV2Serializer(user_obj).data
            )
        else:
            return APIResponse(1, 'failed', user_ser.errors)

    # 单局部改
    def patch(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if not pk:
            return APIResponse(1, 'pk error')
        user_query = models.User.objects.filter(pk=pk, is_delete=False)
        if not user_query:
            return APIResponse(1, 'user error')
        request_data = request.data
        # 局部数据修改，设置 partial=True
        # 视图类给序列化类传递自定义参数 context=值 值一般用字典
        #       在序列化类的钩子函数中用self.context获取传入的值
        user_ser = serializers.UserV2Serializer(context={'arg': '我是视图的'}, partial=True, instance=user_query, data=request_data)
        if user_ser.is_valid():
            user_obj = user_ser.save()
            return APIResponse(0, 'ok',
                               results=serializers.UserV2Serializer(user_obj).data
                               )
        else:
            return APIResponse(1, 'failed', user_ser.errors)

    # 单删
    def delete(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if not pk:
            return APIResponse(1, 'pk error')
        user_obj = models.User.objects.filter(pk=pk, is_delete=False).first()
        if not user_obj:
            return APIResponse(1, '删除失败')
        user_obj.is_delete = True
        user_obj.save()
        return APIResponse(0, '删除成功')