12 ModelSerializer组件
模型类序列化器ModelSerializer
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。
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
1. 定义
比如我们创建一个BookInfoSerializer:
class BookInfoSerializer(serializers.ModelSerializer):
"""图书数据序列化器"""
class Meta:
model = BookInfo
fields = "__all__"
- model 指明参照哪个模型类
- fields 指明为模型类的哪些字段生成
我们可以在python manage.py shell中查看自动生成的BookInfoSerializer的具体实现
>>> from booktest.serializers import BookInfoSerializer
>>> serializer = BookInfoSerializer()
>>> serializer
BookInfoSerializer():
id = IntegerField(label="ID", read_only=True)
btitle = CharField(label="名称", max_length=20)
bpub_date = DateField(allow_null=True, label="发布日期", required=False)
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)
image = ImageField(allow_null=True, label="图片", max_length=100, required=False)
2. 指定字段
- 使用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,如
class BookInfoSerializer(serializers.ModelSerializer):
"""图书数据序列化器"""
class Meta:
model = BookInfo
fields = ("id", "btitle", "bpub_date")
- 使用exclude可以明确排除掉哪些字段
class BookInfoSerializer(serializers.ModelSerializer):
"""图书数据序列化器"""
class Meta:
model = BookInfo
exclude = ("image",)
- 显示指明字段,如:
class HeroInfoSerializer(serializers.ModelSerializer):
hbook = BookInfoSerializer()
class Meta:
model = HeroInfo
fields = ("id", "hname", "hgender", "hcomment", "hbook")
- 指明只读字段
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 BookInfoSerializer(serializers.ModelSerializer):
"""图书数据序列化器"""
class Meta:
model = BookInfo
fields = ("id", "btitle", "bpub_date", "bread", "bcomment")
read_only_fields = ("id", "bread", "bcomment")
3. 添加额外参数
我们可以使用extra_kwargs参数为ModelSerializer添加或修改原有的选项参数
class BookInfoSerializer(serializers.ModelSerializer):
"""图书数据序列化器"""
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},
}
基于 Serializer组件的model、urls、views使用serializers.ModelSerializer重写
4. 序列化
class BookInfoModelSerializer(serializers.ModelSerializer):
# 1.还可以自定义设置序列化字段,但是必须在fields中声明,在fields中写publish_address
# 出版社显示名称,而不是0,1。。。
publish_address = serializers.CharField(source="get_publisher_display", required=False) # 找到对应中文
# 图片显示全路径
image_path = serializers.SerializerMethodField()
def get_image_path(self, obj):
# settings.MEDIA_URL: 自己配置的 /media/,给后面高级序列化与视图类准备的
# obj.icon不能直接作为数据返回,因为内容虽然是字符串,但是类型是ImageFieldFile类型
return "%s%s%s" % (r"http://127.0.0.1:8000", settings.MEDIA_URL, str(obj.image))
# 自定义虚拟阅读量,原基础增加10
fictitious_bread = serializers.SerializerMethodField()
def get_fictitious_bread(self, obj):
return obj.bread + 10
class Meta:
# 序列化关联的model类
model = models.BookInfo
# 参与序列化的字段
fields = (
"id", "pwd", "publisher", "publish_address", "btitle", "bpub_date", "created_time", "bread",
"fictitious_bread", "bcomment", "image", "image_path")
# 指明只读字段,即仅用于序列化输出的字段
read_only_fields = ("publisher_name", "fictitious_bread", "image_path")
5. 反序列化
class BookInfoModelDeSerializer(serializers.ModelSerializer):
pwd = serializers.CharField(label="密码", required=True)
publisher = serializers.IntegerField(label="出版社", required=False)
btitle = serializers.CharField(label="名称", max_length=20)
bpub_date = serializers.DateField(label="发布日期", required=False)
created_time = serializers.DateTimeField(label="创建时间", required=False)
bread = serializers.IntegerField(label="阅读量", required=True)
bcomment = serializers.IntegerField(label="评论量", required=True)
image = serializers.ImageField(label="图片", required=False)
# 自定义有校验规则的反序列化字段,例如确认密码字段re_pwd
re_pwd = serializers.CharField(required=True)
class Meta:
model = models.BookInfo
# 没有默认值的字段必须序列化,为其传值
fields = ("pwd", "re_pwd", "publisher", "btitle", "bpub_date", "created_time", "bread", "bcomment", "image")
# 局部钩子:validate_要校验的字段名(self, 当前要校验字段的值)
# 校验规则:校验通过返回原值,校验失败,抛出异常
def validate_btitle(self, value):
if "django" not in value.lower():
raise exceptions.ValidationError("validate_btitle-图书不是关于Django的")
return value
# 全局钩子:validate(self, 通过系统与局部钩子校验之后的所有数据)
def validate(self, attrs): # attrs是字典格式
pwd = attrs.get("pwd")
re_pwd = attrs.pop("re_pwd") # 因为re_pwd不需要存入数据库,所以在全局钩子校验中删除掉这个字段
print(re_pwd)
bread = attrs["bread"]
bcomment = attrs["bcomment"]
if pwd != re_pwd:
raise exceptions.ValidationError({"pwd&re_pwd": "两次密码不一致"})
if bread < bcomment:
raise serializers.ValidationError("阅读量小于评论量")
return attrs
# 注意:ModelSerializer类已经帮我们实现了 create 与 update 方法,不需要写create就能创建
6 序列化与反序列化整合
序列化层:api/serializers.py
class BookModelSerializer(serializers.ModelSerializer):
pwd = serializers.CharField(label="密码", required=True)
publisher = serializers.IntegerField(label="出版社", required=False)
btitle = serializers.CharField(label="名称", max_length=20)
bpub_date = serializers.DateField(label="发布日期", required=False)
created_time = serializers.DateTimeField(label="创建时间", required=False)
bread = serializers.IntegerField(label="阅读量", required=True)
bcomment = serializers.IntegerField(label="评论量", required=True)
image = serializers.ImageField(label="图片", required=False)
# 序列化自定义字段
# 出版社显示名称,而不是0,1。。。
publisher_name = serializers.CharField(source="get_publisher_display", required=False) # 找到对应中文
# 图片显示全路径
image_path = serializers.SerializerMethodField()
# 自定义虚拟阅读量,原基础增加10
fictitious_bread = serializers.SerializerMethodField()
# 反序列化自定义字段
re_pwd = serializers.CharField(required=True, write_only=True)
class Meta:
model = models.BookInfo
fields = "__all__"
# 只读字段
read_only_fields = (
"id", "pwd", "publisher", "publisher_name", "btitle", "bpub_date", "created_time", "bread",
"fictitious_bread", "bcomment", "image", "image_path")
extra_kwargs = {
"pwd": {
"write_only": True
},
"re_pwd": {
"write_only": True
},
"bpub_date": {
"write_only": True
},
"publisher": {
"write_only": True,
},
"img": {
"read_only": True,
},
"created_time": {
"read_only": True,
},
"publish_name": {
"read_only": True,
}
}
def get_image_path(self, obj):
# settings.MEDIA_URL: 自己配置的 /media/,给后面高级序列化与视图类准备的
# obj.icon不能直接作为数据返回,因为内容虽然是字符串,但是类型是ImageFieldFile类型
return "%s%s%s" % (r"http://127.0.0.1:8000", settings.MEDIA_URL, str(obj.image))
def get_fictitious_bread(self, obj):
return obj.bread + 10
# 局部钩子:validate_要校验的字段名(self, 当前要校验字段的值)
# 校验规则:校验通过返回原值,校验失败,抛出异常
def validate_btitle(self, value):
if "django" not in value.lower():
raise exceptions.ValidationError("validate_btitle-图书不是关于Django的")
return value
# 全局钩子:validate(self, 通过系统与局部钩子校验之后的所有数据)
def validate(self, attrs): # attrs是字典格式
pwd = attrs.get("pwd")
re_pwd = attrs.pop("re_pwd") # 因为re_pwd不需要存入数据库,所以在全局钩子校验中删除掉这个字段
print(re_pwd)
bread = attrs["bread"]
bcomment = attrs["bcomment"]
if pwd != re_pwd:
raise exceptions.ValidationError({"pwd&re_pwd": "两次密码不一致"})
if bread < bcomment:
raise serializers.ValidationError("阅读量小于评论量")
return attrs
# 注意:ModelSerializer类已经帮我们实现了 create 与 update 方法,不需要写create就能创建
序列化层注意点:
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(一般我们把需要存入到数据库中的使用write_only(反序列化),只需要展示的就read_only(序列化),看需求设计)
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)
如果字段没设置write_only或者read_only,那么该字段可以序列化和反序列化
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
7 ModelSerializer总结
class BookSerializer(serializers.ModelSerializer):
model字段或自定义字段
class Meta:
model = models.BookInfo # 与BookInfo表对应
# 使用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=("参与序列化和反序列的字段1","参与序列化和反序列的字段2")
fields = "__all__"
# 使用exclude可以明确排除掉哪些字段
exclude = ("image",)
# 指明只读字段 通过read_only_fields指明只读字段,即仅用于序列化输出的字段
read_only_fields = ("id", "bread", "bcomment")
# 为ModelSerializer添加或修改原有的选项参数
extra_kwargs = {
}
# 局部钩子:validate_要校验的字段名(self, 当前要校验字段的值)
# 校验规则:校验通过返回原值,校验失败,抛出异常
def validate_btitle(self, value):
....
return value
# 全局钩子:validate(self, 通过系统与局部钩子校验之后的所有数据)
def validate(self, attrs): # attrs是字典格式
...
return attrs