Django REST Framework 自定义字段验证

Question

我正在尝试为模型创建自定义验证，以检查其 start_date 是否在其 end_date 之前，事实证明这几乎是不可能的。

我尝试过的东西:

• 内置的 Django 验证器:没有检查这个

• 像这样写我自己的:

  def validate_date(self):
     if self.start_date < self.end_date:
          raise serializers.ValidationError("End date must be after start date.")
  

我已经添加到 Serializer 类(然后是模型)的那段代码，但它似乎没有在任何一个位置被调用。

我还找到了this一些可能有用的代码，但我不知道如何将其集成到我的方法中 - 似乎可以验证一个模型属性，但我需要在两个属性之间进行检查。

我的模型:

class MyModel(models.Model):

    created = models.DateTimeField(auto_now_add=True)
    relation_model = models.ForeignKey(RelationModel, related_name="mymodels")
    priority = models.IntegerField(
        validators = [validators.MinValueValidator(0), validators.MaxValueValidator(100)])
    start_date = models.DateField()
end_date = models.DateField()

    @property
    def is_active(self):
        today = datetime.date.today()
        return (today >= self.start_date) and (today <= self.end_date)

    def __unicode__(self):
        ...

    class Meta:
        unique_together = ('relation_model', 'priority', 'start_date', 'end_date')

仅供引用，所有其他验证都有效!

我的序列化器:

class MyModelSerializer(serializers.ModelSerializer):

    relation_model = RelationModelSerializer
    is_active = serializers.Field(source='is_active')

    def validate_date(self):
        if self.start_date > self.end_date:
            raise serializers.ValidationError("End date must be after start date.")   

    class Meta:
        model = MyModel
        fields = (
            'id', 'relation_model', 'priority', 'start_date', 'end_date', 'is_active'
        )

我的看法:

class MyModelList(generics.ListCreateAPIView):
    permission_classes = (IsAdminUser,)
    queryset = MyModel.objects.all()
    serializer_class = MyModelSerializer
    ordering = ('priority')

Answer 1

您应该使用对象范围的验证 (validate())，因为 validate_date 永远不会被调用，因为 date 不是序列化器。 From the documentation :

class MySerializer(serializers.ModelSerializer):
    def validate(self, data):
        """
        Check that the start is before the stop.
        """
        if data['start_date'] > data['end_date']:
            raise serializers.ValidationError("finish must occur after start")
        return data

根据 Michel Sabchuk 的建议，您可以将验证错误添加到 end_date 字段:

class MySerializer(serializers.ModelSerializer):
    def validate(self, data):
        """
        Check that the start is before the stop.
        """
        if data['start_date'] > data['end_date']:
            raise serializers.ValidationError({"end_date": "finish must occur after start"})
        return data

另一种可能性是创建一个验证器。我根据 UniqueTogetherValidator 的代码创建了一个:

from rest_framework.utils.representation import smart_repr

class DateBeforeValidator:
    """
    Validator for checking if a start date is before an end date field.
    Implementation based on `UniqueTogetherValidator` of Django Rest Framework.
    """
    message = _('{start_date_field} should be before {end_date_field}.')

    def __init__(self, start_date_field="start_date", end_date_field="end_date", message=None):
        self.start_date_field = start_date_field
        self.end_date_field = end_date_field
        self.message = message or self.message

    def __call__(self, attrs):
        if attrs[self.start_date_field] > attrs[self.end_date_field]:
            message = self.message.format(
                start_date_field=self.start_date_field,
                end_date_field=self.end_date_field,
            )
            # Replace the following line with
            #   raise serializers.ValidationError(
            #       {self.end_date_field: message},
            #       code='date_before',
            #   )
            # if you want to raise the error on the field level
            raise serializers.ValidationError(message, code='date_before')

    def __repr__(self):
        return '<%s(start_date_field=%s, end_date_field=%s)>' % (
            self.__class__.__name__,
            smart_repr(self.start_date_field),
            smart_repr(self.end_date_field)
        )


class MySerializer(serializers.ModelSerializer):
    class Meta:
        # If your start/end date fields have another name give them as kwargs tot the
        # validator:
        #   DateBeforeValidator(
        #       start_date_field="my_start_date", 
        #       end_date_field="my_end_date",
        #   )
        validators = [DateBeforeValidator()]

在 DRF 3.0 之前，您还可以将它添加到模型的清理函数中，但在 DRF 3.0 中不再调用它。

class MyModel(models.Model):
    start_date = models.DateField()
    end_date = models.DateField()
    def clean(self):
        if self.end_date < self.start_date:
            raise ValidationError("End date must be after start date.")