python - DRF 序列化器将某些模型实例的字段更改为 read_only

Question

我有这个模型:

class Task(MPTTModel, TimeStampedModel, StartFinishModel):
    name = models.CharField(max_length=256)
    parent = TreeForeignKey('self',
                            on_delete=models.CASCADE,
                            related_name='children')
    start_date = models.DateField()    
    finish_date = models.DateField()
    @property
    def is_stage(self):
        if self.get_children():
            return True
        return False

和序列化器:

class TaskBaseSerializer(StartFinishSerializer, TimeStampedSerializer):
    class Meta:
        model = Task
        fields = ('id', 'name', 'parent', 'start_date', 'finish_date', 'is_stage')    
        read_only_fields = ('is_stage')

如果 is_stage 属性为 True，我希望将字段 'start_date' 和 'finish_date' 设为 read_only >。我怎样才能做到这一点？

Answer 1

尝试重写 __init__() 方法，如下所示:

class TaskBaseSerializer(StartFinishSerializer, TimeStampedSerializer):
    class Meta:
        model = Task
        fields = ('id', 'name', 'parent', 'start_date', 'finish_date', 'is_stage')    
        read_only_fields = ('is_stage')

    def __init__(self, *args, **kwargs):
        super(TaskBaseSerializer, self).__init__(*args, **kwargs)
        if self.instance and getattr(self.instance, 'is_stage', None):
            self.fields['start_date'].read_only = True
            self.fields['finish_date'].read_only = True