如何在mongoengine棉花糖中序列化十进制字段？

Question

我在mongoengine中有一个十进制字段，我试图返回存储在模型中的数据，但是当我尝试返回对象时，我在编码中收到错误

TypeError: Object of type 'Decimal' is not JSON serializable

class PaymentTransactionSchema(Document):
    meta = {
        'collection': 'payment_transaction'
    }
    payment_mode = StringField()
    payment_reference_code = StringField()

    currency = StringField()
    amount = DecimalField()
    status = StringField()

    approval_code = StringField()
    remarks = StringField()

    createdate = DateTimeField(default=datetime.datetime.utcnow)


class ProjectFundTransaction(ModelSchema):
    class Meta:
        model = ProjectFundTransactionSchema

然后像这样的回报

self.__transaction = PaymentTransactionSchema(**args)
res = self.__transaction.save()
transaction = self.dump(res).data

我希望棉花糖能够自动处理此问题，但似乎我错过了某个地方的配置