PrimaryKeyRelatedField（source =＆＃39; order.market＆＃39;，read_only = True）给出一个AttributeError

Question

models.py

class ClientTransaction(model.Models):
    order = models.ForeignKey('main.Order', related_name='client_transaction', on_delete=models.PROTECT, null=True)

class Order(BaseModel):
    market = models.ForeignKey('main.Market', on_delete=models.PROTECT, related_name='order')

serializers.py

class ClientTransactionSerializer(ModelSerializer):
    market = serializers.PrimaryKeyRelatedField(source='order.market', read_only=True)

    class Meta:
        model = ClientTransaction
        fields=['market']

给出错误：AttributeError：＆＃39; NoneType＆＃39;对象没有属性＆＃39;市场＆＃39;

django == 2，djangorestframework =＆gt; 3.7.1

full error image

Answer 1

您需要自定义序列化程序以从ForeignKey字段获取数据。在描述的情况下，您尝试获取未初始化的订单。 尝试使用SerializerMethodField来处理此错误。例如：

class ClientTransactionSerializer(ModelSerializer):
    market = serializers.SerializerMethodField()

    def get_market(self, obj):
        return obj.order.market if obj.order else None

    class Meta:
        model = ClientTransaction
        fields=['market']