Django将Serializer过滤器仅嵌套到一个字段，而不是所有字段

Question

我有两个序列化器，如下所示。下面代码段的输出是Workers，并且包含所有字段（ticket_counter，ticket_counter_name，worker）的相关票证计数器详细信息。但我只需要一个ticket_counter_name的领域。

class WorkerSerializer(serializers.ModelSerializer):

    ticket_counter = WorkerToCounterSerializer(many=True, read_only=True)

    class Meta:
        model = User
        fields = (
                  'username',
                  'ticket_counter',
                  )

class WorkerToCounterSerializer(serializers.ModelSerializer):
    ticket_counter = SerializerMethodField()
    ticket_counter_name = serializers.CharField(source='ticket_counter.ticket_counter_name')

    class Meta:
        model = WorkerToTicketCounter
        list_serializer_class = FilteredListSerializer
        fields = (
            'ticket_counter',
            'ticket_counter_name',
            'worker',
        )

    def get_ticket_counter(self, obj):
        return obj.ticket_counter.pk

class FilteredListSerializer(ListSerializer):
    def to_representation(self, data):
        data = data.filter(worker_to_ticket_counter_is_deleted=False)[:1]
        return super(FilteredListSerializer, self).to_representation(data)

上面的片段输出

{
        "username": "xxxxxxxxxxx",
        "ticket_counter": [
            {
                "ticket_counter": 7,
                "ticket_counter_name": "Entrance Counter",
                "worker": 4,

            }
        ]
 }

但我想要的是

 {
        "username": "xxxxxxxxxxx",
        "ticket_counter": "Entrance Counter"
 }

我只需要ticket_counter_name的名字。在我的情况下，工人不能有两个ticket_counters。显然，它只给出一个ticket_counter。可能吗？

编辑：使用字符串StringRelatedField

{
    "username": "xxxxxxxxxxx",
    "ticket_counter": [
          "Entrance Counter",
          "xxxxxxxxxxxxxxxx",
          "xxxxxxxxxxxxxxxx",
          "xxxxxxxxxxxxxxxx"
    ]
}

编辑：WorkerToTicketCounter模型

class WorkerToTicketCounter(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    ticket_counter = models.ForeignKey(TicketCounter, related_name="workers")
    worker = models.ForeignKey(User, related_name='ticket_counter')
    worker_to_ticket_counter_is_deleted = models.BooleanField(default=False)

Answer 1

如果我理解正确，您只需要一个SerializerMethodField来执行过滤和字符串重复。

class WorkerSerializer(serializers.ModelSerializer):
    ticket_counter = serializers.SerializerMethodField(read_only=True)

    def get_ticket_counter(self, user):
        qs = user.ticket_counter.filter(worker_to_ticket_counter_is_deleted=False)
        if qs.exists() and hasattr(qs.first().ticket_counter, 'ticket_counter_name'):
            return qs.first().ticket_counter.ticket_counter_name
        return None

    class Meta:
        model = User
        fields = ('username', 'ticket_counter',)

Answer 2

你可以使用StringRelatedField：

class WorkerSerializer(serializers.ModelSerializer):

    ticket_counter = StringRelatedField(many=True, read_only=True)

    class Meta:
        model = User
        fields = (
                  'username',
                  'ticket_counter',
                  )

注意使用StringRelatedField你应该将__str__方法添加到你的WorkerToTicketCounter模型：

class WorkerToTicketCounter:
    ...
    def __str__(self):
        return self.ticket_counter.ticket_counter_name