ModelSerializer 序列化
序列化准备
- 模型层：models.py
from django.db import models
# 1.基表模型类的封装（建立公有字段）
class BaseModel(models.Model):
is_delete = models.BooleanField(default=False)
create_time = models.DateTimeField(auto_now_add=True) # 创建的时候更新时间
# 作为基表的model一定要加上，迁移命令之后不会在数据库中生成表
class Meta:
abstract = True
class Book(BaseModel):
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,
related_name="books",
on_delete=models.DO_NOTHING
)
authors = models.ManyToManyField(to="Author",
db_constraint=False,
related_name='books',
)
def fn(self):
return 'fn fn fn '
# 序列化插拔式属性 - 完成自定义字段名完成连表查询
@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 = '书籍表'
verbose_name_plural = verbose_name
def __str__(self):
return self.name
class Publish(BaseModel):
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 = models.CharField(max_length=64)
age = models.IntegerField()
class Meta:
db_table = 'author'
verbose_name = '作者表'
verbose_name_plural = verbose_name
def __str__(self):
return self.name
class AuthorDetail(BaseModel):
mobile = models.CharField(max_length=11)
author = models.OneToOneField(to="Author",
db_constraint=False,
on_delete=models.CASCADE,
related_name='detail'
)
db_constraint=False断关联
# 1.作者删除，详情也跟着删除 - on-delete = models.CASCADE
# 2.作者删除，详情置空 - null =True ,on-delete = models.SET_NULL
# 3.作者删除，详情重置 default=0,on_delete = models.SET_DEFAULT
# 4.作者删除，详情不动 on_delete = models.DD_NOTHING
class Meta:
db_table = 'authorDetail'
verbose_name = '作者详情'
verbose_name_plural = verbose_name
db_constraint=False断关联
"""
1、外键位置：
一对多 - 外键放多的一方
一对一 - 从逻辑正反向考虑，如作者表与作者详情表，作者删除级联删除详情，详情删除作者依旧存在，所以建议外键在详情表中
多对多 - 外键在关系表中
2、ORM正向方向连表查找：
正向：通过外键字段 eg: author_detial_obj.author
反向：通过related_name的值 eg：author_obj.detail
注：依赖代码见下方
3、连表操作关系：
1）作者删除，详情级联 - on_delete=models.CASCADE
2）作者删除，详情置空 - null=True, on_delete=models.SET_NULL
3）作者删除，详情重置 - default=0, on_delete=models.SET_DEFAULT
4）作者删除，详情不动 - on_delete=models.DO_NOTHING
注：拿作者与作者详情表举例
4、外键关联字段的参数 - 如何实现 断关联、目前表间操作关系、方向查询字段
i）作者详情表中的
author = models.OneToOneField(
to='Author',
related_name='detail',
db_constraint=False,
on_delete=models.CASCADE
)
ii）图书表中的
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不能设置on_delete，OneToOneField、ForeignKey必须设置on_delete（django1.x系统默认级联，但是django2.x必须手动明确）
"""
- 后台管理层：admin.py
```注册
from django.contrib import admin
from . import models
admin.site.register(models.User) # 只要需要后台操作都要注册
- 配置层：settings.py
# 注册rest_framework
INSTALLED_APPS = [
# ...
'rest_framework',
]
# media资源
MEDIA_URL = '/media/' # 后期高级序列化类与视图类，会使用该配置
MEDIA_ROOT = os.path.join(BASE_DIR, 'media') # media资源路径
# 国际化配置
LANGUAGE_CODE = 'zh-hans'
TIME_ZONE = 'Asia/Shanghai'
USE_I18N = True
USE_L10N = True
USE_TZ = False
#### 序列化使用
##在api中建立一个serializers.py文件夹
- 序列化层：api/serializers.py
from rest_framework.serializers import ModelSerializer, SerializerMethodField
from . import models
class PublishModelSerializer(ModelSerializer):
class Meta:
model = models.Publish
fields = '__all__'
# 序列化发送数据给前端
class BookModelSerializer(ModelSerializer):
# 了解，这样的字段规定了必须查找在fileds中申明，否则报错
# publish_address = SerializerMethodField()
#
# def get_publish_address(self, obj):
# return obj.publish.address
# 自定义连表深度 - 子序列化方式,定义之后必须在fields注册，否则报错
publish = PublishModelSerializer()
class Meta:
# 序列化关联的model类
model = models.Book
# 参与序列化的字段
fields = ('name', 'price', 'img', 'publish_name', 'author_list','publish')
# fields ='__all__' # 显示所有字段
# exclude = ("id", "is_delete", "create_time") # 除开哪些字段
# 自动连表深度
# depth =1
# 视图层（views）
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": '书籍不存在',
})
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": '访问成功',
"results": book_data
})
## 反序列化
##### 序列化层：api/serializers.py
class BookModelDeserializer(ModelSerializer):
class Meta:
model = models.Book
fields = ('name', 'price', 'publish', 'authors')
# extra_kwargs 用来完成反序列化字段的 系统校验规则 “required：True 必须校验
extra_kwargs = {
'name': {
'required': True,
'min_length': 1,
'error_messages': {
'required': '必填项',
'min_length': '太短',
}
}
}
# 局部钩子
def validate_name(self, value):
# 书名不能包含 g 字符
if 'g' in value.lower():
raise ValidationError('该g书不能出版')
return value
# 全局钩子
def validate(self, attrs):
publish = attrs.get('publish')
name = attrs.get('name')
if models.Book.objects.filter(name=name, publish=publish):
raise ValidationError({'book': '该书已存在'})
return attrs
# ModelSerializer类已经帮我们实现了 create 与 update 方法
```
##### 视图层：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：当校验失败，马上终止当前视图方法，抛异常返回给前台
book_ser.is_valid(raise_exception=True)
book_obj = book_ser.save()
return Response({
'status': 0,
'msg': 'ok',
'results': serializers.BookModelSerializer(book_obj).data
})
```
##### 路由层：api/urls.py
urlpatterns = [
url(r'^books/$', views.Book.as_view()),
url(r'^books/(?P<pk>.*)/$', views.Book.as_view()),
]
```
## 序列化与反序列化整合（重点）
##### 序列化层：api/serializers.py
1) fields中设置所有序列化与反序列化字段
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
自定义字段默认只序列化(read_only)
3) 设置反序列化所需的 系统、局部钩子、全局钩子 等校验规则
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': '必填项',
'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):
# 书名不能包含 g 字符
if 'g' in value.lower():
raise ValidationError('该g书不能出版')
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': '该书已存在'})
return attrs
```
##### 视图层：api/views.py
class V2Book(APIView):
# 单查：有pk
# 群查：无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': '书籍不存在'
})
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
})
# 单增：传的数据是与model对应的字典
# 群增：传的数据是 装多个 model对应字典 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': '数据有误',
})
book_ser = serializers.V2BookModelSerializer(data=request_data, many=many)
# 当校验失败，马上终止当前视图方法，抛异常返回给前台
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
})
# 单删：有pk
# 群删：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': '删除成功',
})
return Response({
'status': 1,
'msg': '删除失败',
})
```
##### 路由层：api/urls.py
urlpatterns = [
url(r'^v2/books/$', views.V2Book.as_view()),
url(r'^v2/books/(?P<pk>.*)/$', views.V2Book.as_view()),
]
```