drf框架 ModelSerializer

 

ModelSerializer

 

一、准備

配置settings.py

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

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'dg_proj',
        'USER': 'root',
        'PASSWORD': '123',
    }
}
"""
任何__init__文件
import pymysql
pymysql.install_as_MySQLdb()
"""

LANGUAGE_CODE = 'zh-hans'
TIME_ZONE = 'Asia/Shanghai'
USE_I18N = True
USE_L10N = True
USE_TZ = False

MEDIA_URL = '/media/'
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

路由

# 主
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
from django.conf.urls import url
from . import views
urlpatterns = [
    
]

 

多表設計

"""
Book表：name、price、img、authors、publish、is_delete、create_time

Publish表：name、address、is_delete、create_time
    
Author表：name、age、is_delete、create_time

AuthorDetail表：mobile, author、is_delete、create_time
    
BaseModel基表
    is_delete、create_time
上面四表繼承基表，可以繼承兩個字段
"""

 

基表

class BaseModel(models.Model):
    is_delete = models.BooleanField(default=False)
    create_time = models.DateTimeField(auto_now_add=True)

    # 設置 abstract = True 來聲明基表，作為基表的Model不能在數據庫中形成對應的表
    class Meta:
        abstract = True

 

斷關聯多表關系

重點：

"""
1、外鍵位置：
    一對多 - 外鍵放多的一方
    一對一 - 從邏輯正反向考慮，如作者表與作者詳情表，作者刪除級聯刪除詳情，詳情刪除作者依舊存在，所以建議外鍵在詳情表中
    多對多 - 外鍵在關系表中
    
2、ORM正向方向連表查找：
    正向：通過外鍵字段 eg: author_detial_obj.author 
    反向：通過related_name的值 eg：author_obj.detail
    注：依賴代碼見下方
    
3、連表操作關系：
    1）作者刪除，詳情級聯 - on_delete=models.CASCADE
    2）作者刪除，詳情置空 - null=True, on_delete=models.SET_NULL
    3）作者刪除，詳情重置 - default=0, on_delete=models.SET_DEFAULT
    4）作者刪除，詳情不動 - on_delete=models.DO_NOTHING
    注：拿作者與作者詳情表舉例
    
4、外鍵關聯字段的參數 - 如何實現 斷關聯、目前表間操作關系、方向查詢字段
    i）作者詳情表中的
    author = models.OneToOneField(
        to='Author',
        related_name='detail',
        db_constraint=False,
        on_delete=models.CASCADE
    )
    
    ii）圖書表中的
    publish = models.ForeignKey(
        to='Publish',
        related_name='books',
        db_constraint=False,
        on_delete=models.DO_NOTHING,
    )
    authors = models.ManyToManyField(
        to='Author'
        related_name='books',
        db_constraint=False,
    )
    注：ManyToManyField不能設置on_delete，OneToOneField、ForeignKey必須設置on_delete（django1.x系統默認級聯，但是django2.x必須手動明確）
"""

 

model類

from django.db import models

# 圖書管理系統：Book、Author、AuthorDetail、Publish
"""
Book表: name、price、img、authors、publish、is_delete、create_time
Publish表: name、address、is_delete、create_time
Author表: name、age、is_delete、create_time
AuthorDetail表: mobile, author、is_delete、create_time
"""

# 1) 基表
class BaseModel(models.Model):
    is_delete = models.BooleanField(default=False)
    create_time = models.DateTimeField(auto_now_add=True)

    # 作為基表的Model不能在數據庫中形成對應的表，設置 abstract = True
    class Meta:
        abstract = True


class Book(BaseModel):
    """name、price、img、authors、publish、is_delete、create_time"""
    name = models.CharField(max_length=64)
    price = models.DecimalField(max_digits=5, decimal_places=2)
    img = models.ImageField(upload_to='img', default='img/default.jpg')
    publish = models.ForeignKey(
        to='Publish',
        db_constraint=False,  # 斷關聯
        related_name='books',  # 反向查詢字段：publish_obj.books 就能訪問所有出版的書
        on_delete=models.DO_NOTHING,  # 設置連表操作關系
    )
    authors = models.ManyToManyField(
        to='Author',
        db_constraint=False,
        related_name='books'
    )

    # 序列化插拔式屬性 - 完成自定義字段名完成連表查詢
    @property
    def publish_name(self):
        return self.publish.name

    @property
    def author_list(self):
        return self.authors.values('name', 'age', 'detail__mobile').all()

    class Meta:
        db_table = 'book'
        verbose_name = '書籍'
        verbose_name_plural = verbose_name
    def __str__(self):
        return self.name

class Publish(BaseModel):
    """name、address、is_delete、create_time"""
    name = models.CharField(max_length=64)
    address = models.CharField(max_length=64)

    class Meta:
        db_table = 'publish'
        verbose_name = '出版社'
        verbose_name_plural = verbose_name
    def __str__(self):
        return self.name

class Author(BaseModel):
    """name、age、is_delete、create_time"""
    name = models.CharField(max_length=64)
    age = models.IntegerField()

    class Meta:
        db_table = 'author'
        verbose_name = '作者'
        verbose_name_plural = verbose_name
    def __str__(self):
        return self.name

class AuthorDetail(BaseModel):
    """mobile, author、is_delete、create_time"""
    mobile = models.CharField(max_length=11)
    author = models.OneToOneField(
        to='Author',
        db_constraint=False,
        related_name='detail',
        on_delete=models.CASCADE,
    )

    class Meta:
        db_table = 'author_detail'
        verbose_name = '作者詳情'
        verbose_name_plural = verbose_name
    def __str__(self):
        return '%s的詳情' % self.author.name

 

 

二、序列化

序列化層：api/serializers.py

from rest_framework.serializers import ModelSerializer, SerializerMethodField
from rest_framework.exceptions import ValidationError
from . import models

# 可以單獨作為Publish接口的序列化類，也可以作為Book序列化外鍵publish輔助的序列化組件
class PublishModelSerializer(ModelSerializer):
    class Meta:
        model = models.Publish
        fields = ('name', 'address')

class BookModelSerializer(ModelSerializer):
    # 了解: 該方式設置的序列化字段，必須在fields中聲明
    # publish_address = SerializerMethodField()
    # def get_publish_address(self, obj):
    #     return obj.publish.address

    # 自定義連表深度 - 子序列化方式 - 該方式不能參與反序列化，使用在序列化反序列化共存時，不能書寫
    publish = PublishModelSerializer()

    class Meta:
        # 序列化類關聯的model類
        model = models.Book
        # 參與序列化的字段
        fields = ('name', 'price', 'img', 'author_list', 'publish')

        # 了解知識點
        # 所有字段
        # fields = '__all__'
        # 與fields不共存，exclude排除哪些字段
        # exclude = ('id', 'is_delete', 'create_time')
        # 自動連表深度
        # depth = 1

視圖層：api/views.py

class Book(APIView):
    def get(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:
            try:
                book_obj = models.Book.objects.get(pk=pk, is_delete=False)
                book_data = serializers.BookModelSerializer(book_obj).data
            except:
                return Response({
                    'status': 1,
                    'msg': '書籍不存在'
                })
        else:
            book_query = models.Book.objects.filter(is_delete=False).all()
            book_data = serializers.BookModelSerializer(book_query, many=True).data
        return Response({
            'status': 0,
            'msg': 'ok',
            'results': book_data
        })

路由層：api/urls.py

urlpatterns = [
    url(r'^books/$', views.Book.as_view()),
    url(r'^books/(?P<pk>.*)/$', views.Book.as_view()),
]

 

三、反序列化

序列化層：api/serializers.py

class BookModelDeserializer(ModelSerializer):
    class Meta:
        model = models.Book
        fields = ('name', 'price', 'publish', 'authors')
        # extra_kwargs 用來完成反序列化字段的 系統校驗規則
        extra_kwargs = {
            'name': {
                'required': True,
                'min_length': 1,
                'error_messages': {
                    'required': '必填項',
                    'min_length': '太短',
                }
            }
        }
    
    # 局部鈎子
    def validate_name(self, value):
        # 書名不能包含 g 字符
        if 'g' in value.lower():
            raise ValidationError('該g書不能出版')
        return value
    # 全局鈎子
    def validate(self, attrs):
        publish = attrs.get('publish')
        name = attrs.get('name')
        if models.Book.objects.filter(name=name, publish=publish):
            raise ValidationError({'book': '該書已存在'})
        return attrs

    # ModelSerializer類已經幫我們實現了 create 與 update 方法

視圖層：api/views.py

class Book(APIView):
    def post(self, request, *args, **kwargs):
        request_data = request.data
        book_ser = serializers.BookModelDeserializer(data=request_data)
        # raise_exception=True：當校驗失敗，馬上終止當前視圖方法，拋異常返回給前台
        book_ser.is_valid(raise_exception=True)
        book_obj = book_ser.save()
        return Response({
            'status': 0,
            'msg': 'ok',
            'results': serializers.BookModelSerializer(book_obj).data
        })

路由層

urlpatterns = [
    url(r'^books/$', views.Book.as_view()),
    url(r'^books/(?P<pk>.*)/$', views.Book.as_view()),
]

 

四、序列化與反序列化整合（*******）

序列化層：api/serializers.py

"""
1) fields中設置所有序列化與反序列化字段
2) extra_kwargs划分只序列化或只反序列化字段
    write_only：只反序列化
    read_only：只序列化
    自定義字段默認只序列化(read_only)
3) 設置反序列化所需的 系統、局部鈎子、全局鈎子 等校驗規則
"""
class V2BookModelSerializer(ModelSerializer):
    class Meta:
        model = models.Book
        fields = ('name', 'price', 'img', 'author_list', 'publish_name', 'publish', 'authors')
        extra_kwargs = {
            'name': {
                'required': True,
                'min_length': 1,
                'error_messages': {
                    'required': '必填項',
                    'min_length': '太短',
                }
            },
            'publish': {
                'write_only': True
            },
            'authors': {
                'write_only': True
            },
            'img': {
                'read_only': True,
            },
            'author_list': {
                'read_only': True,
            },
            'publish_name': {
                'read_only': True,
            }
        }

    def validate_name(self, value):
        # 書名不能包含 g 字符
        if 'g' in value.lower():
            raise ValidationError('該g書不能出版')
        return value

    def validate(self, attrs):
        publish = attrs.get('publish')
        name = attrs.get('name')
        if models.Book.objects.filter(name=name, publish=publish):
            raise ValidationError({'book': '該書已存在'})
        return attrs

 

視圖層

class V2Book(APIView):
    # 單查：有pk
    # 群查：無pk
    def get(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:
            try:
                book_obj = models.Book.objects.get(pk=pk, is_delete=False)
                book_data = serializers.V2BookModelSerializer(book_obj).data
            except:
                return Response({
                    'status': 1,
                    'msg': '書籍不存在'
                })
        else:
            book_query = models.Book.objects.filter(is_delete=False).all()
            book_data = serializers.V2BookModelSerializer(book_query, many=True).data
        return Response({
            'status': 0,
            'msg': 'ok',
            'results': book_data
        })

    # 單增：傳的數據是與model對應的字典
    # 群增：傳的數據是 裝多個 model對應字典 的列表
    def post(self, request, *args, **kwargs):
        request_data = request.data
        if isinstance(request_data, dict):
            many = False
        elif isinstance(request_data, list):
            many = True
        else:
            return Response({
                'status': 1,
                'msg': '數據有誤',
            })
        book_ser = serializers.V2BookModelSerializer(data=request_data, many=many)
        # 當校驗失敗，馬上終止當前視圖方法，拋異常返回給前台
        book_ser.is_valid(raise_exception=True)
        book_result = book_ser.save()
        return Response({
            'status': 0,
            'msg': 'ok',
            'results': serializers.V2BookModelSerializer(book_result, many=many).data
        })

    # 單刪：有pk
    # 群刪：有pks   |  {"pks": [1, 2, 3]}
    def delete(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:
            pks = [pk]
        else:
            pks = request.data.get('pks')
        if models.Book.objects.filter(pk__in=pks, is_delete=False).update(is_delete=True):
            return Response({
                'status': 0,
                'msg': '刪除成功',
            })
        return Response({
            'status': 1,
            'msg': '刪除失敗',
        })

路由層

urlpatterns = [
    url(r'^v2/books/$', views.V2Book.as_view()),
    url(r'^v2/books/(?P<pk>.*)/$', views.V2Book.as_view()),
]

 

五、單整體改put、單局部改patch）

路由、模型、序列化層無需修改

視圖層：

"""
1) 單整體改，說明前台要提供修改的數據，那么數據就需要校驗，校驗的數據應該在實例化“序列化類對象”時，賦值給data
2）修改，就必須明確被修改的模型類對象，並在實例化“序列化類對象”時，賦值給instance
3）整體修改，所有校驗規則有required=True的字段，都必須提供，因為在實例化“序列化類對象”時，參數partial默認為False


注：如果partial值設置為True，就是可以局部改
1）單整體修改，一般用put請求：
V2BookModelSerializer(
    instance=要被更新的對象, 
    data=用來更新的數據,
    partial=默認False，必須的字段全部參與校驗
)
2）單局部修改，一般用patch請求：
V2BookModelSerializer(
    instance=要被更新的對象, 
    data=用來更新的數據,
    partial=設置True，必須的字段都變為選填字段
)
    注：partial設置True的本質就是使字段 required=True 校驗規則失效
"""

class V2Book(APIView):
    # 單整體改: 對 v2/books/(pk)/ 傳的數據是與model對應的字典{name|price|publish|authors}
    def put(self, request, *args, **kwargs):
        request_data = request.data
        pk = kwargs.get('pk')
        old_book_obj = models.Book.objects.filter(pk=pk).first()
        # 目的：將眾多數據的校驗交給序列化類來處理 - 讓序列化類扮演反序列化角色，校驗成功后，序列化類來幫你入庫
        book_ser = serializers.V2BookModelSerializer(instance=old_book_obj, data=request_data, partial=False)
        book_ser.is_valid(raise_exception=True)
        # 校驗通過，完成數據的更新：要更新的目標，用來更新的新數據
        book_obj = book_ser.save()

        return Response({
            'status': 0,
            'msg': 'ok',
            'results': serializers.V2BookModelSerializer(book_obj).data
        })

 

六、群改VS局部修改

序列化層

# 重點：ListSerializer與ModelSerializer建立關聯的是：
# ModelSerializer的Meta類的 - list_serializer_class
class V2BookListSerializer(ListSerializer):
    def update(self, instance, validated_data):
        # print(instance)  # 要更新的對象們
        # print(validated_data)  # 更新的對象對應的數據們
        # print(self.child)  # 服務的模型序列化類 - V2BookModelSerializer
        for index, obj in enumerate(instance):
            self.child.update(obj, validated_data[index])
        return instance
    
# 原模型序列化類變化
class V2BookModelSerializer(ModelSerializer):
    class Meta:
        # ...
        # 群改，需要設置 自定義ListSerializer，重寫群改的 update 方法
        list_serializer_class = V2BookListSerializer
    # ...

視圖層

class V2Book(APIView):
    # 單局部改：對 v2/books/(pk)/ 傳的數據，數據字段key都是選填
    # 群局部改：對 v2/books/ 
    # 請求數據 - [{pk:1, name:123}, {pk:3, price:7}, {pk:7, publish:2}]
    def patch(self, request, *args, **kwargs):
        request_data = request.data
        pk = kwargs.get('pk')

        # 將單改，群改的數據都格式化成 pks=[要需要的對象主鍵標識] | request_data=[每個要修改的對象對應的修改數據]
        if pk and isinstance(request_data, dict):  # 單改
            pks = [pk, ]
            request_data = [request_data, ]
        elif not pk and isinstance(request_data, list): # 群改
            pks = []
            for dic in request_data:  # 遍歷前台數據[{pk:1, name:123}, {pk:3, price:7}, {pk:7, publish:2}]，拿一個個字典
                pk = dic.pop('pk', None)
                if pk:
                    pks.append(pk)
                else:
                    return Response({
                        'status': 1,
                        'msg': '數據有誤',
                    })
        else:
            return Response({
                'status': 1,
                'msg': '數據有誤',
            })

        # pks與request_data數據篩選，
        # 1）將pks中的沒有對應數據的pk與數據已刪除的pk移除，request_data對應索引位上的數據也移除
        # 2）將合理的pks轉換為 objs
        objs = []
        new_request_data = []
        for index, pk in enumerate(pks):
            try:
                # pk對應的數據合理，將合理的對象存儲
                obj = models.Book.objects.get(pk=pk)
                objs.append(obj)
                # 對應索引的數據就需要保存下來
                new_request_data.append(request_data[index])
            except:
                # 重點：反面教程 - pk對應的數據有誤，將對應索引的data中request_data中移除
                # index = pks.index(pk)
                # request_data.pop(index)
                continue

        book_ser = serializers.V2BookModelSerializer(instance=objs, data=new_request_data, partial=True, many=True)
        book_ser.is_valid(raise_exception=True)
        book_objs = book_ser.save()

        return Response({
            'status': 0,
            'msg': 'ok',
            'results': serializers.V2BookModelSerializer(book_objs, many=True).data
        })