如果我们想要使用序列化器对应的是Django的模型类,DRF为我们提供了ModelSerializer模型类序列化器来帮助我们快速创建一个Serializer类。
一、创建序列化器
class BookSerializer(serializers.ModelSerializer):
# 图书数据序列化器
# model 指明该序列化器处理的数据字段从模型类BookInfo参考生成
# fields 指明该序列化器包含模型类中的哪些字段,'__all__'指明包含所有字段
class Meta:
model = BookInfo
fields = '__all__'
class HeroSerializer(serializers.ModelSerializer):
# 图书数据序列化器
# model 指明该序列化器处理的数据字段从模型类HeroInfo参考生成
# fields 指明该序列化器包含模型类中的哪些字段,'__all__'指明包含所有字段
class Meta:
model = HeroInfo
fields = '__all__'
fields
来明确字段,
__all__
表名包含所有字段,也可以写明具体哪些字段 :
fields = ('id', 'btitle', 'bpub_date')
exclude可以明确排除掉哪些字段
exclude = ('image',)
3) 默认ModelSerializer使用主键作为关联字段
>>> from booktest.serializers import HeroSerializer
>>> serializer = HeroSerializer()
>>> serializer
HeroSerializer():
id = IntegerField(label='ID', read_only=True)
hname = CharField(label='名称', max_length=20)
hgender = ChoiceField(choices=((0, 'male'), (1, 'female')), label='性别', required=False, validators=[, ])
hcomment = CharField(allow_null=True, label='描述信息', max_length=200, required=False)
is_delete = BooleanField(label='逻辑删除', required=False)
hbook = PrimaryKeyRelatedField(label='图书', queryset=BookInfo.objects.all())
depth来简单的生成嵌套表示,depth应该是整数,表明嵌套的层级数量。如:
class HeroInfoSerializer2(serializers.ModelSerializer):
class Meta:
model = HeroInfo
fields = '__all__'
depth = 1
测试结果如下:
>>> from booktest.serializers import HeroInfoSerializer2
>>> serializer = HeroInfoSerializer2()
>>> serializer
HeroInfoSerializer2():
id = IntegerField(label='ID', read_only=True)
hname = CharField(label='名称', max_length=20)
hgender = ChoiceField(choices=((0, 'male'), (1, 'female')), label='性别', required=False, validators=[, ])
hcomment = CharField(allow_null=True, label='描述信息', max_length=200, required=False)
is_delete = BooleanField(label='逻辑删除', required=False)
hbook = NestedSerializer(read_only=True):
id = IntegerField(label='ID', read_only=True)
btitle = CharField(label='名称', max_length=20)
bpub_date = DateField(label='发布日期')
bread = IntegerField(label='阅读量', max_value=2147483647, min_value=-2147483648, required=False)
bcomment = IntegerField(label='评论量', max_value=2147483647, min_value=-2147483648, required=False)
is_delete = BooleanField(label='逻辑删除', required=False)
image = ImageField(allow_null=True, label='图片', max_length=100, required=False)
4) 显示指明字段,如:
class HeroSerializer3(serializers.ModelSerializer):
hbook = BookSerializer()
class Meta:
model = HeroInfo
fields = ('id','hname','hgender','hcomment','hbook')
测试结果:
>>> from booktest.serializers import HeroSerializer3
>>> from booktest.models import HeroInfo
>>> serializer = HeroSerializer3()
>>> serializer
HeroSerializer3():
id = IntegerField(label='ID', read_only=True)
hname = CharField(label='名称', max_length=20)
hgender = ChoiceField(choices=((0, 'male'), (1, 'female')), label='性别', required=False, validators=[, ])
hcomment = CharField(allow_null=True, label='描述信息', max_length=200, required=False)
hbook = BookSerializer():
id = IntegerField(label='ID', read_only=True)
btitle = CharField(label='名称', max_length=20)
bpub_date = DateField(label='发布日期')
bread = IntegerField(label='阅读量', max_value=2147483647, min_value=-2147483648, required=False)
bcomment = IntegerField(label='评论量', max_value=2147483647, min_value=-2147483648, required=False)
is_delete = BooleanField(label='逻辑删除', required=False)
image = ImageField(allow_null=True, label='图片', max_length=100, required=False)
可以通过read_only_fields指明只读字段,即仅用于序列化输出的字段
class BookSerializer2(serializers.ModelSerializer):
class Meta:
model = BookInfo
fields = ('id', 'btitle', 'bpub_date', 'bread', 'bcomment')
read_only_fields = ('id', 'bread', 'bcomment')
二、查看序列化器
>>> from booktest.serializers import BookSerializer,HeroSerializer
>>> serializer = BookSerializer()
>>> serializer
BookSerializer():
id = IntegerField(label='ID', read_only=True)
btitle = CharField(label='名称', max_length=20)
bpub_date = DateField(label='发布日期')
bread = IntegerField(label='阅读量', max_value=2147483647, min_value=-2147483648, required=False)
bcomment = IntegerField(label='评论量', max_value=2147483647, min_value=-2147483648, required=False)
is_delete = BooleanField(label='逻辑删除', required=False)
image = ImageField(allow_null=True, label='图片', max_length=100, required=False)
>>> serializer = HeroSerializer()
>>> serializer
HeroSerializer():
id = IntegerField(label='ID', read_only=True)
hname = CharField(label='名称', max_length=20)
hgender = ChoiceField(choices=((0, 'male'), (1, 'female')), label='性别', required=False, validators=[, ])
hcomment = CharField(allow_null=True, label='描述信息', max_length=200, required=False)
is_delete = BooleanField(label='逻辑删除', required=False)
hbook = PrimaryKeyRelatedField(label='图书', queryset=BookInfo.objects.all())
ModelSerializer与常规的Serializer相同,但提供了:
基于模型类自动生成一系列字段
基于模型类自动为Serializer生成validators,比如unique_together
包含默认的create()和update()的实现
如果创建序列化器对象的时候,没有传递instance实例,则调用save()方法的时候,create()被调用,相反,如果传递了instance实例,则调用save()方法的时候,update()被调用。
下面以图书数据的序列化器演示序列化器的使用
如下:添加数据库
>>> from booktest.serializers import BookSerializer
>>> from booktest.models import BookInfo
>>> from datetime import date
>>> data = {'btitle':'武则天传奇','bpub_date':date(1990,3,5)}
>>> serializer = BookSerializer(data=data) # 没有传递instance实例,新建数据
>>> serializer.is_valid()
True
>>> serializer.save()
如下:更新数据库>>> from booktest.models import BookInfo
>>> from booktest.serializers import BookSerializer
>>> from datetime import date
>>> book = BookInfo.objects.get(id=9) # 实例:instance
>>> book
>>> data={'btitle':'三国演义<改编版>','bpub_date':date(1992,5,8)}
>>> serializer = BookSerializer(book,data=data) # 传进了instance参数,表示更新数据库
>>> serializer.is_valid()
True
>>> serializer.save()
>
四、添加额外参数
class BookSerializer(serializers.ModelSerializer):
# 图书数据序列化器
# model 指明该序列化器处理的数据字段从模型类BookInfo参考生成
# fields 指明该序列化器包含模型类中的哪些字段,'__all__'指明包含所有字段
class Meta:
model = BookInfo
fields = '__all__'
# 使用extra_kwargs参数为ModelSerializer添加或修改原有的选项参数
class BookSerializer3(serializers.ModelSerializer):
class Meta:
model = BookInfo
fields = ('id', 'btitle', 'bpub_date', 'bread', 'bcomment')
extra_kwargs={
'bread':{'min_value':0,'required':True},
'bcomment':{'min_value':0,'required':True}
}
测试:
# 做对比:
>>> from booktest.serializers import BookSerializer,BookSerializer3
>>> ser = BookSerializer()
>>> ser
BookSerializer():
id = IntegerField(label='ID', read_only=True)
btitle = CharField(label='名称', max_length=20)
bpub_date = DateField(label='发布日期')
bread = IntegerField(label='阅读量', max_value=2147483647, min_value=-2147483648, required=False)
bcomment = IntegerField(label='评论量', max_value=2147483647, min_value=-2147483648, required=False)
is_delete = BooleanField(label='逻辑删除', required=False)
image = ImageField(allow_null=True, label='图片', max_length=100, required=False)
# 测试添加参数的序列化器
>>> ser2 = BookSerializer3()
>>> ser2
BookSerializer3():
id = IntegerField(label='ID', read_only=True)
btitle = CharField(label='名称', max_length=20)
bpub_date = DateField(label='发布日期')
bread = IntegerField(label='阅读量', max_value=2147483647, min_value=0, required=True)
bcomment = IntegerField(label='评论量', max_value=2147483647, min_value=0, required=True)