Django Rest框架序列化字典而不创建模型 [英] django rest framework serialize a dictionary without create a model

问题描述

我的数据是这样的，我想序列化它们而不为它们创建模型。

My data is like this, I want to serialize them without creating model for them.

[
  {'form': 1, 'count': 1},
  {'form': 2, 'count': 3}
]

序列化为

[
  {'form': 'my form name 1', 'count': 1},
  {'form': 'my form name 2', 'count': 3}
]

我要使用序列化器对其进行序列化，并通过pk获取表单名称。

I want to serialize it with serializer, get form name form model by pk.

class EavForm(models.Model):
    name = models.CharField(max_length=300)
    order = models.IntegerField(default=1)


# serializer
class CustomSerializer(serializers.Serializer):
    form = serializers.PrimaryKeyRelatedField(queryset=EavForm.objects.all())
    count = serializers.IntegerField()

某些错误，例如'int '对象没有属性'pk'

在python控件中进行测试

test in python control

d = [{'form': 1, 'count': 1}, {'form': 2, 'count': 1}]
s = CustomSerializer(d, many=True)
print(s.data)

# error
Traceback (most recent call last):
  File "backend/src/db_tools/del1.py", line 25, in <module>
    print(s.data)
  File "backend/lib/python3.7/site-packages/rest_framework/serializers.py", line 768, in data
    ret = super(ListSerializer, self).data
  File "backend/lib/python3.7/site-packages/rest_framework/serializers.py", line 262, in data
    self._data = self.to_representation(self.instance)
  File "backend/lib/python3.7/site-packages/rest_framework/serializers.py", line 686, in to_representation
    self.child.to_representation(item) for item in iterable
  File "backend/lib/python3.7/site-packages/rest_framework/serializers.py", line 686, in <listcomp>
    self.child.to_representation(item) for item in iterable
  File "backend/lib/python3.7/site-packages/rest_framework/serializers.py", line 530, in to_representation
    ret[field.field_name] = field.to_representation(attribute)
  File "backend/lib/python3.7/site-packages/rest_framework/relations.py", line 272, in to_representation
    return value.pk
AttributeError: 'int' object has no attribute 'pk'

推荐答案

通过执行以下更改可以实现所需的功能。

What you want,can be achived by doing following changes.

class EavForm(models.Model):
    name = models.CharField(max_length=300)
    order = models.IntegerField(default=1)


# serializer
class EvaFormPKRelatedField(PrimaryKeyRelatedField):
    def get_queryset(self):
        return EavForm.objects.all()

    def to_representation(self, value):
        return value.name


class CustomSerializer(serializers.Serializer):
    form = EvaFormPKRelatedField()
    count = serializers.IntegerField()

# Assume EvaForm exist of id 1 and 2
data = [{'form': 1, 'count': 1}, {'form': 2, 'count': 1}]
s = CustomSerializer(data=data, many=True)
print(s.data) 
""" Output
[
  {'form': 'my form name 1', 'count': 1},
  {'form': 'my form name 2', 'count': 3}
]
"""

print(s.validated_data)
""" Output
[
  {'form': <EvaForm: Evaform object (1)>, 'count': 1},
  {'form': <EvaForm: Evaform object (2)>, 'count': 3}
]
"""

请注意， .data 和 .validated_data 的输出有所变化。

Please note that, there is changes in output of .data and .validated_data .

1. .data 将为您提供 PrimaryKeyRelatedField 的值通过调用 .to_representation（）方法。

1. .data will give you value of PrimaryKeyRelatedField by calling .to_representation() method.

.validated_d ata 通过调用 .to_internal_value（）方法将为您提供 PrimaryKeyRelatedField 的值。因为，已验证的数据通过调用所有验证来获得每个字段的价值，并且在内部运行验证之前，每个字段的值将通过调用其 to_internal_value（）方法进行更新，并且该值用于验证过程。

.validated_data will give you value of PrimaryKeyRelatedField by calling .to_internal_value() method. Because, validated data got it's value for each field by calling it's all validations, and internally before running validations each field value will be updated by calling it's to_internal_value() method and that value is used for validation process.

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