Question

我有一个表格，希望显示拟议投资的多个养老基金的提用金额。我已经在表中的“投资”实例上编写了一个for循环。但是，我似乎无法从此循环中检索到金额。我认为我的queryset'amountdrawdown'是不正确的，因为我正试图反向查找外键（从Investment模型到DrawdownOnFund模型）。

我的models.py，简化了：

class PensionFund(models.Model):
    name = models.CharField() 

class PensionFundDeposit(models.Model):
    PensionFund = models.ForeignKey(PensionFund)
    date = models.DateField()
    amount = models.DecimalField()
    undrawn = models.DecimalField()

class Investment(models.Model):          <---- Looping over this
    amount = models.DecimalField()
    date = models.DateField()

class DrawdownOnFund(models.Model):
    Investment = models.ForeignKey(Investment) 
    PensionFund = models.ForeignKey(PensionFund)
    date = models.DateField()
    amount = models.DecimalField()   <---- I would like to retrieve this

我的serializer.py，简化了：

class PensionFundSerializer(serializers.ModelSerializer):
    class Meta:
        fields = ['id', 'name']

class PensionFundDepositSerializer(serializers.ModelSerializer):
    class Meta:
        fields = ['id', 'fund','date','amount','undrawn', 'fundname']

class InvestmentSerializer(serializers.ModelSerializer):
    amountdrawdown = serializers.CharField(source='drawdown.amount')  <---My attempt to write a query to retrieve the amount
    class Meta:
        fields = ['id', 'amount', 'date', 'amountdrawdown']

class DrawdownOnFundSerializer(serializers.ModelSerializer):
    class Meta:
        fields = ['id', 'call', 'commitment', 'date', 'amount', 'callid']

Answer 1

Investment-> DrawdownOnFund具有1-Many关系。因此，DrawdownonFund将与Investment实例之一相关。并且，在反向类中（即Investment）将有一个DrawdownOnFund实例的列表，其反向查找字段的名称为drawdownonfund_set（默认情况下）。

因此，考虑到这种情况，您想要显示与一项投资相关的所有提款资金的清单，您应该使用嵌套的序列化器模式。

class DrawdownOnFundSerializer(serializers.ModelSerializer):
    class Meta:
        fields = ['id', 'call', 'commitment', 'date', 'amount', 'callid']

class InvestmentSerializer(serializers.ModelSerializer):
    amountdrawdowns = DrawdownOnFundSerializer(many=True, source='drawdownonfund_set')
    class Meta:
        fields = ['id', 'amount', 'date', 'amountdrawdowns']

对Investment模型的一个实例进行反序列化输出将如下所示。您可以通过管理amountdrawdowns来控制DrawdownOnFundSerializer中每个项目的显示字段。

{
  "id": "1",
  "amount": "",
  "date": "",
  "amountdrawdowns": [
    {
      "id": "",
      "call": "",
      "commitment": "",
      "date": "",
      "amount": "",
      "callid": ""
    }  
  ]
}

Django REST序列化程序queryset：通过反向外键访问模型？

1 个答案: