DRF，將自定義字段添加到ModelSerializer

Question

我的項目中有一些模型，我需要API的特殊響應，我正在使用Django Rest框架。

class Goal(models.Model):
    name = models.CharField()
    # more fields

class Task(models.Model):
    name = models.CharField()
    goal = models.ForeignKey(Goal)

class UserTask(models.Model):
    goal = models.ForeignKey(Goal)
    user = models.ForeignKey(User)
    # other fields

我有這個回應：

{
  "name": "One goal",
  "task": [
    {
      "name": "first task"
    },
    {
      "name": "second tas"
    }
  ]
}

但是我需要這個：

{
  "name": "One goal",
  "task": [
    {
      "name": "first task",
      "is_in_usertask": true
    },
    {
      "name": "second tas",
      "is_in_usertask": false
    }
  ]
}

我在DRF文檔中看到了這一點，但我不知道如何通過當前用戶（或URL paramenter中給出的其他用戶）和每個Goal過濾UserTask 。

編輯：

# serializers

class TaskSerializer(serializers.ModelSerializer):
    class Meta:
        model = Task


class GoalSerializer(serializers.ModelSerializer):
    # related_name works fine
    tasks = TaskSerializer(many=True)

    class Meta:
        model = Goal

Answer 1

看一下這個對話： 如何在Django-Rest-Framework序列化程序中獲取Request.User？

您無法直接訪問request.user

Answer 2

嘗試使用SerializerMethodField字段作為

class TaskSerializer(serializers.ModelSerializer):
    is_in_usertask = serializers.SerializerMethodField(read_only=True)

    class Meta:
        model = Task
        fields = ('name', 'is_in_usertask')

    def get_is_in_usertask(self, task): return UserTask.objects.filter(user=self.context['request'].user, goal=task.goal).exists()