Django-rest-framework中的可写嵌套序列化器? [英] Writable nested serializer in django-rest-framework?
问题描述
我的设计如下关于Django ModelSerializer。
有模型A和模型B。模型B具有模型A的外键字段。由于某些原因,我不能直接使用主键来序列化模型B。按照我的想法,我需要序列化其他两个字段(在模型A中唯一)。
我看到SlugRelatedField必须用于一个子字段。
我搜索了一个NaturalKeyField可以支持NaturalKeyField。但看起来它被django-rest-framework取代。但是我检查了django-rest-framework,根本没有这样的领域。
谁能帮忙?我该怎么办?
代码如下。
模型A
class AssetModel(models.Model):
org = models.ForeignKey(Org, related_name ='models')
name = models.CharField(max_length = 128)
model_type = models.SmallIntegerField(默认= 3,choices = MODEL_TYPE)
目录= models.CharField(max_length = 128)
...
class Meta:
unique_together =('org','name',)
模型B
class Dataitem(models.Model):
mod = models.ForeignKey(AssetModel,related_name ='dataitems')
name = models.CharField(max_length = 128)
data_type = models.SmallIntegerField(default = 0,choices = DATAITEM_DATATYPE)
。 ..
模型A的序列化器
类AssetModelSerializer(serializers.ModelSerializer):
org = serializers.SlugRelatedField(queryset = Org.objects.all(),slug_field ='name')
类元:
模型= AssetM odel
fields =('org','name','model_type',..
模型B的序列化器
类DataitemSerializer(serializers.ModelSerializer):
类元:
模型= Dataitem
字段=('mod','name','data_type'...)
模型A的主键只是一个Django自动添加的id。序列化模型B时,我需要获取模型A的组织和名称。读和写都需要。
嵌套序列化器
您可以执行以下操作,为 Dataitem
定义一个序列化器,该序列化器可以重用 AssetModel
模型
class AssetModelSerializer(serializers.ModelSerializer):
class Meta:
model = AssetModel
#默认情况下将包含字段组织和AssetModel名称
class DataitemSerializer(serializers.ModelSerializer):
类元:
模型= Dataitem
mod = AssetModelSerializer()
#这是Dataitem.mod字段
#这是AssetModel的FK,
#现在将使用AssetModelSerializer
#对其进行序列化,并包括AssetModelSerializer
$ b $的组织和名称字段b
我更喜欢这种方法,因为使用我得到的控制。
如果您使用上述序列化,您将获得如下结构:
data_item = {'name':.. 。,'mod':{'org':...,'name':...}}
^
| ___ AssetModel字段
或者,您也可以使用 depth = n
您还可以在 Dataitem
<中使用
depth = 1
pre> 类DataitemSerializer(serializers.ModelSerializer):
类元:
模型=数据项
深度= 1#将包括相关模型的字段
#例如将Mod FK转换为AssetModel
可写嵌套序列化器
< blockquote>
由于嵌套创建和更新的行为可能含糊不清,
可能需要相关模型之间的复杂依赖性,因此REST
框架3要求您始终明确地编写这些方法。
我们必须实现 create / update
才能使其按照< a href = http://www.django-rest-framework.org/api-guide/serializers/#writable-nested-representations rel = noreferrer> DRF的文档
类DataitemSerializer(serializers.ModelSerializer):
类元:
模型= Dataitem
#嵌套序列化器
mod = AssetModelSerializer()
#自定义create()
def create(self,validated_data):
#首先我们为AssetModel创建'mod'数据
mod_data = validated_data.pop('mod')
asset_model = AssetModel.objects.create(** mod_data)
#现在我们创建Dataitem并设置Dataitem.mod FK
dataitem = Dataitem.objects.create(mod = asset_model,* * validated_data)
#返回一个Dataitem实例
返回一个dataitem
My design is as following about Django ModelSerializer. There are model A and model B. Model B has a foreign key field of Model A. For some reasons, I can not use the primary key directly to serialize Model B. As my thought, what I need is to serialize two other fields(unique together in Model A).
And I see the SlugRelatedField must be used for one slug field. I searched there is a NaturalKeyField can support NaturalKeyField. But it looks like it is superseeded by django-rest-framework. But I checked the django-rest-framework, there is no such field at all. Can anyone help?? What should I do?
The code is as following. Model A
class AssetModel(models.Model):
org = models.ForeignKey(Org, related_name='models')
name = models.CharField(max_length=128)
model_type = models.SmallIntegerField(default = 3,choices = MODEL_TYPE )
directory = models.CharField(max_length = 128)
...
class Meta:
unique_together = ('org', 'name',)
Model B
class Dataitem(models.Model):
mod = models.ForeignKey(AssetModel, related_name='dataitems')
name = models.CharField(max_length=128)
data_type = models.SmallIntegerField(default =0,choices = DATAITEM_DATATYPE)
...
Serializer of model A
class AssetModelSerializer(serializers.ModelSerializer):
org = serializers.SlugRelatedField(queryset=Org.objects.all(), slug_field='name')
class Meta:
model = AssetModel
fields = ('org', 'name', 'model_type',..
Serializer of model B
class DataitemSerializer(serializers.ModelSerializer):
class Meta:
model = Dataitem
fields = ('mod', 'name','data_type'...)
The primary key of Model A is just a id Django auto added. When serialize the model B, I need to get the org and name of model A. Both read and write are needed.
Nested Serializer
You can do something like this, define a serializer for Dataitem
that can reuse a serializer of the AssetModel
model
class AssetModelSerializer(serializers.ModelSerializer):
class Meta:
model = AssetModel
# Fields org and name of AssetModel will be inlcuded by default
class DataitemSerializer(serializers.ModelSerializer):
class Meta:
model = Dataitem
mod = AssetModelSerializer()
# This is the Dataitem.mod field
# which is a FK to AssetModel,
# Now it'll be serilized using the AssetModelSerializer
# and include the org and name fields of AssetModelSerializer
I prefer this approach because of the control I get. If you serialize using the above you get a structure like this:
data_item = {'name': ..., 'mod': {'org': ..., 'name': ...}}
^
|___ AssetModel fields
Alternatively you can also use depth = n
You can also use depth = 1
in Dataitem
class DataitemSerializer(serializers.ModelSerializer):
class Meta:
model = Dataitem
depth = 1 # Will include fields from related models
# e.g. the mod FK to AssetModel
Writable Nested Serializer
Because the behavior of nested creates and updates can be ambiguous, and may require complex dependencies between related models, REST framework 3 requires you to always write these methods explicitly.
We have to implement create/update
to make this writable as per DRF's documentation
class DataitemSerializer(serializers.ModelSerializer):
class Meta:
model = Dataitem
# Nested serializer
mod = AssetModelSerializer()
# Custom create()
def create(self, validated_data):
# First we create 'mod' data for the AssetModel
mod_data = validated_data.pop('mod')
asset_model = AssetModel.objects.create(**mod_data)
# Now we create the Dataitem and set the Dataitem.mod FK
dataitem = Dataitem.objects.create(mod=asset_model, **validated_data)
# Return a Dataitem instance
return dataitem
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