在 DRF 3 中的 ModelSerializer 上添加非模型字段

Question

如何在 DRF 3 中的 ModelSerializer 上添加非模型字段？即添加一个在我的实际模型中不存在的字段？

class TestSerializer(serializers.ModelSerializer):
    url = serializers.HyperlinkedIdentityField(view_name='vote_detail')
    non_field = serializers.CharField()  # no corresponding model property.


    class Meta:
        model = vote_model
        fields = ("url", "non_field")

    def create(self, validated_data):
      print(direction=validated_data['non_field'])

但是 DRF 3 给了我错误：

Got AttributeError when attempting to get a value for field `non_field` on serializer `TestSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `Test` instance.
Original exception text was: 'Test' object has no attribute 'non_field'.

我搜索了堆栈 DRF - ModelSerializer with a non-model write_only field 并找到了一些解决方案，但这些解决方案是指我使用 DRF 3 的 DRF 2。在这个版本上是否有解决方案？

Answer 1

举个例子可能会对你有所帮助。

  class ExtensibleModelSerializerOptions(serializers.SerializerOptions):
    """
    Meta class options for ModelSerializer
    """
    def __init__(self, meta):
        super(ExtensibleModelSerializerOptions, self).__init__(meta)
        self.model = getattr(meta, 'model', None)
        self.read_only_fields = getattr(meta, 'read_only_fields', ())
        self.non_native_fields = getattr(meta, 'non_native_fields', ())


class ExtensibleModelSerializer(serializers.ModelSerializer):

    _options_class = ExtensibleModelSerializerOptions

    def restore_object(self, attrs, instance=None):
        """
        Deserialize a dictionary of attributes into an object instance.
        You should override this method to control how deserialized objects
        are instantiated.
        """
        for field in self.opts.non_native_fields:
            attrs.pop(field)

        return super(ExtensibleModelSerializer, self).restore_object(attrs, instance)

来源： https://github.com/tomchristie/django-rest-framework/issues/951

Answer 2

class TestSerializer(serializers.ModelSerializer):
    url = serializers.HyperlinkedIdentityField(view_name='vote_detail')
    non_field = serializers.SerializerMethodField()  # no corresponding model property.

    class Meta:
        model = vote_model
        fields = ("url", "non_field")

    def create(self, validated_data):
        print(direction=validated_data['non_field'])

http://www.django-rest-framework.org/api-guide/fields/#serializermethodfield

或通过这个link

Answer 3

class Foo(models.Model):
    . . .
    @property
    def my_field(self):
        return stuff
    . . .

来源：

Django REST Framework: adding additional field to ModelSerializer

Answer 4

class MySerializer(serializers.ModelSerializer):
    write_only_char_field = serializers.CharField(write_only=True)
    write_only_list_char_field = serializers.ListField(child=serializers.CharField(max_length=100, default=''), write_only=True)
    empty_method_field = serializers.SerializerMethodField()
    read_only_custom_model_field = serializers.CharField(source='custom_property', read_only=True)

    def create(self, validated_data):
        validated_data.pop('write_only_char_field', None)
        validated_data.pop('write_only_list_char_field', None)
        return super().create(validated_data)

serializers.CharField(write_only=True) 和 serializers.ListField(...) 是一个很好的解决方案，可以为您的 .create() 和 .update() 方法提供额外的数据，作为单个字符串或字符串列表（您可以将 ListField 与其他序列化程序混合使用字段类型）。
使用这种方法，您还可以定义def validate_write_only_char_field 来实现一些快速简单的验证。

serializers.SerializerMethodField() 允许您从序列化器上定义的方法向序列化器输出添加一些自定义只读字段。

read_only_custom_model_field 将使用模型上的方法来读取一些数据，严格来说不是模型字段，而是自定义方法。即

class MyModel(models.Model):
    my_field = models.CharField(max_length=100)

    @property
    def custom_property(self):
        return "Perform calculations, combine with related models, etc. etc."

Answer 5

如前所述，有两种方法。 (1) 添加模型属性。 (2) 添加模型字段。我觉得在这篇文章中很好地解释了向模型添加@property。如果您想让您的模型“精益求精”，请使用 Method 字段。不过，Chandus 的回答省略了一些关键点：

class DeliveryItemSerializer(serializers.ModelSerializer):

    product_name = serializers.SerializerMethodField(read_only=True)

    def get_product_name(self, obj):
        return obj.product.name

    class Meta:
        model = DeliveryItem
        fields = (
            (...your field names),
            'product_name',)

1. 设置只读
2. 字段和对应的方法名称不同。方法名称默认为get_field_name。如果您使用其他名称，请使用 SerializerMethodField() 上的 method_name=method 名称参数