python - Django Rest Framework 使用 filterset_fields 在 ViewSet 中过滤计算出的 SerializerMethodField()

Question

我有一个 SerializerMethodField 计算下一个执行日期加上上次执行时间的小时数

简化代码，有这个模型:

class Activity(BaseModel):
    name = models.CharField(max_length=250)
    last_execution = models.DateTimeField()

    def __str__(self):
        return self.name

    class Meta:
        ordering = ('name',)

为了在下一次执行时发送到前端，我的 Serializer 中有这个 SerializerMethodField()

class ActivitySerializer(serializers.ModelSerializer):
    next_execution = serializers.SerializerMethodField('get_next_execution')

    class Meta:
        model = Activity
        fields = ('id', 'name', 'last_execution', 'next_execution',)

    def get_next_execution(self, data):
        # last = ActivityExecute.objects.filter(activity_id=data.id).order_by('-executed_at').first()
        # time = data.periodicity_type.time_in_hour
        # if last:
        #     if data.equipment.hour_meter > -1:
        #         return last.executed_at + timedelta(hours=time - (data.equipment.hour_meter - last.hour_meter))
        #     return last.executed_at + timedelta(hours=time)
        # 
        # return data.equipment.created_at + timedelta(hours=time)
        return data.last_execution + timedelta(hours=24)

但是当我尝试像这样将计算字段添加到 filterset_fields 时:

class ActivityViewSet(viewsets.ModelViewSet):
    permission_classes = (IsAuthenticated,)

    serializer_class = ActivitySerializer
    filter_backends = (filters.DjangoFilterBackend,)
    filterset_fields = {
        'id': ['exact'],
        'name': ['icontains', 'exact'],
        'last_execution': ['exact'],
        'next_execution': ['exact'],
    }

    def get_object(self):
        return super(ActivityViewSet, self).get_object()

    def get_queryset(self):
        return Activity.objects.all()

我遇到了这个错误:'Meta.fields' 不得包含非模型字段名称:next_execution

有一种方法可以将 SerializerMethodField() 添加到 filterset_fields 中吗？使用方法 get_queryset 将使我在该计算字段(注释)中的所有逻辑都被复制。该字段工作正常，问题只是前端使用查询参数过滤值。

Answer 1

如果您可以将一个包添加到您的项目中，那么 django-property-filter 会很容易

只需将您的序列化程序代码转换为如下属性:

class Activity(BaseModel):
    name = models.CharField(max_length=250)
    last_execution = models.DateTimeField()

    def __str__(self):
        return self.name

    class Meta:
        ordering = ('name',)

    @property
    def next_execution(self):
        # all your logic in comment can be pasted here
        return self.last_execution + timedelta(hours=24)  

从 serializer 中删除您的 SerializerMethodField() 和 def get_next_execution 但将其保留在字段列表中，此属性将列为字段还有

class ActivitySerializer(serializers.ModelSerializer):

    class Meta:
        model = Activity
        fields = ('id', 'name', 'last_execution', 'next_execution',)

现在，在 View 中，从您的 ViewSet 中删除 filterset_fields，我们将把它添加到 FilterSet 类中...

为您的 ViewSet 创建一个 FilterSet

from django_property_filter import PropertyFilterSet, PropertyDateFilter

class ActivityFilterSet(PropertyFilterSet):
    next_execution = PropertyDateFilter(field_name='next_execution', lookup_expr='exact') # this is the @property that will be filtered as a DateFilter, you can change the variable name, just keep the `field_name` right

    class Meta:
        model = Activity
        fields = { # here is the filterset_fields property
            'id': ['exact'],
            'name': ['icontains', 'exact'],
            'last_execution': ['exact'],
        }

然后，只需将这个 FilterSet 添加到您的 ViewSet 中，奇迹就会发生

class ActivityViewSet(viewsets.ModelViewSet):
    permission_classes = (IsAuthenticated,)

    serializer_class = ActivitySerializer
    filter_backends = (filters.DjangoFilterBackend,)
    filterset_class = ActivityFilterSet

    def get_object(self):
        return super(ActivityViewSet, self).get_object()

    def get_queryset(self):
        return Activity.objects.all()