python - Django 休息框架。更新嵌套对象

Question

我在更新嵌套对象时遇到问题。

所以我有一个结构类似于这个的模型:

class Invoice(models.Model):
    nr = models.CharField(max_length=100)
    title = models.CharField(max_length=100)

class InvoiceItem(models.Model):
    name = models.CharField(max_length=100)
    price = models.FloatField()
    invoice = models.ForeignKey(Invoice, related_name='items')

我需要从父对象创建子对象，我的意思是在创建 Invoice 对象时直接创建 InvoiceItems。 为此，我编写了以下序列化程序:

class InvoiceItemSerializer(serializers.ModelSerializer):
    invoice = serializers.PrimaryKeyRelatedField(queryset=Invoice.objects.all(), required=False)
    class Meta:
        model = InvoiceItem


class InvoiceSerializer(serializers.ModelSerializer):
    items = InvoiceItemSerializer(many=True)

    class Meta:
        model = Invoice

    def create(self, validated_data):
        items = validated_data.pop('items', None)
        invoice = Invoice(**validated_data)
        invoice.save()
        for item in items:
            InvoiceItem.objects.create(invoice=invoice, **item)
        return invoice

到目前为止，create/read/delete 方法都可以正常工作，除了 update。 我认为下面的逻辑应该是正确的，但它遗漏了一些东西。

def update(self, instance, validated_data):
    instance.nr = validated_data.get('nr', instance.nr)
    instance.title = validated_data.get('title', instance.title)
    instance.save()

    # up till here everything is updating, however the problem appears here.
    # I don't know how to get the right InvoiceItem object, because in the validated
    # data I get the items queryset, but without an id.

    items = validated_data.get('items')
    for item in items:
        inv_item = InvoiceItem.objects.get(id=?????, invoice=instance)
        inv_item.name = item.get('name', inv_item.name)
        inv_item.price = item.get('price', inv_item.price)
        inv_item.save()

    return instance

任何帮助将不胜感激。

Answer 1

这就是我完成任务的方式:

我已将 id 字段添加到 InvoiceItemSerializer

class InvoiceItemSerializer(serializers.ModelSerializer):
    ...
    id = serializers.IntegerField(required=False)
    ...

以及InvoiceSerializer

的更新方法

def update(self, instance, validated_data):
    instance.nr = validated_data.get('nr', instance.nr)
    instance.title = validated_data.get('title', instance.title)
    instance.save()

    items = validated_data.get('items')

    for item in items:
        item_id = item.get('id', None)
        if item_id:
            inv_item = InvoiceItem.objects.get(id=item_id, invoice=instance)
            inv_item.name = item.get('name', inv_item.name)
            inv_item.price = item.get('price', inv_item.price)
            inv_item.save()
        else:
            InvoiceItem.objects.create(account=instance, **item)

    return instance

同样在 create 方法中，如果通过了 id，我将弹出它。