向Django模型添加验证

Question

I am using django rest framework for an app. Below is the Feature model :

class Feature(models.Model):
    image_component = models.ForeignKey('Image_Component',on_delete=models.CASCADE,)
    feature_type = models.CharField(max_length = 20 )
    feature_value = models.CharField(max_length = 30)


    def save(self , *args , **kwargs):
        if not self.feature_type in ['size','quality','format']:
            raise Exception("Incorrect")
        else:
            super(Feature, self).save(*args , **kwargs)

    def validate(self , data):
        if data['feature_type'] == 'size':
            print self.feature_value.is_alnum()
            if not data['feature_value'].is_alnum():
                raise serializers.ValidationError('Incorrect value')
        return data

The serializer class for feature model is :

class FeatureSerializer(serializers.ModelSerializer):
    class Meta:
        model = Feature
        field = ('id','feature_value')

Below is the corresponding view :

class Feature(generics.ListCreateAPIView):
    queryset = Feature.objects.all()
    serializer_class = FeatureSerializer

I want to validate the model such that if any user is inputing the value for feature_value as size then he/she can input it only in the form of "200x200"(if not this then alphanumeric). I tried to do this in the validate function in Feature model but its not working.Can someone tell me how to rectify this error.

Also the print statement in the validate method doesn't print anything which means the validate method is not at all called as said in the doc.

Answer 1

Code not tested. Using argument validators in CharField method

def validate_feature_type(self , data):
        if data['feature_type'] == 'size':
            print self.feature_value.is_alnum()
            if not data['feature_value'].is_alnum():
                raise serializers.ValidationError('Incorrect value')

class Feature(models.Model):
    image_component = models.ForeignKey('Image_Component', on_delete=models.CASCADE,)
    feature_type = models.CharField(max_length = 2, validators=[validate_feature_type] )
    feature_value = models.CharField(max_length = 30)