Django Filters多值查询异常：vehicle_type参数拆分错误求助

问题场景 #

我想用逗号分隔的查询参数过滤vehicle_type字段，请求URL示例：

{{url}}/vehicles-records-info/75d9ee1b-8a03-4697-82e7-2d96ef0a8c2d/?vehicle_type=Mixer,Lorry

错误表现 #

打印生成的SQL查询时，得到的语句是：

...  AND "vehicle_type" IN (M, i, x, e, r, ,, L, o, y)) 

预期结果 #

正确的SQL语句应为：

...  AND "vehicle_type" IN ('Mixer', 'Lorry')) 

当前使用的Filter代码 #

class VehicularAccessRecordInformationFilter(django_filters.FilterSet):
    vehicle_type = django_filters.CharFilter(field_name='vehicle_type', lookup_expr='in')
    start_timestamp = django_filters.DateTimeFilter(field_name='timestamp', lookup_expr='gte')
    end_timestamp = django_filters.DateTimeFilter(field_name='timestamp', lookup_expr='lte')

    class Meta:
        model = VehicleAccessRecordInformation
        fields = ['vehicle_type', 'timestamp']

解决方案 #

问题核心是CharFilter会把传入的字符串当作单个值处理，而in查询需要的是列表格式。以下两种方法可解决：

方法1：自定义过滤器处理逻辑 #

重写filter方法，将逗号分隔的参数拆分为列表：

class VehicularAccessRecordInformationFilter(django_filters.FilterSet):
    vehicle_type = django_filters.CharFilter(field_name='vehicle_type', method='filter_vehicle_type')
    start_timestamp = django_filters.DateTimeFilter(field_name='timestamp', lookup_expr='gte')
    end_timestamp = django_filters.DateTimeFilter(field_name='timestamp', lookup_expr='lte')

    def filter_vehicle_type(self, queryset, name, value):
        # 拆分参数并去除空值
        values = [v.strip() for v in value.split(',') if v.strip()]
        if values:
            return queryset.filter(**{f'{name}__in': values})
        return queryset

    class Meta:
        model = VehicleAccessRecordInformation
        fields = ['vehicle_type', 'timestamp']

方法2：使用django-filter内置的In过滤器 #

继承BaseInFilter和CharFilter，直接实现列表参数处理：

from django_filters import BaseInFilter, CharFilter

class CharInFilter(BaseInFilter, CharFilter):
    pass

class VehicularAccessRecordInformationFilter(django_filters.FilterSet):
    vehicle_type = CharInFilter(field_name='vehicle_type', lookup_expr='in')
    start_timestamp = django_filters.DateTimeFilter(field_name='timestamp', lookup_expr='gte')
    end_timestamp = django_filters.DateTimeFilter(field_name='timestamp', lookup_expr='lte')

    class Meta:
        model = VehicleAccessRecordInformation
        fields = ['vehicle_type', 'timestamp']

两种方法都能将vehicle_type=Mixer,Lorry解析为['Mixer', 'Lorry']，生成符合预期的SQL语句。

内容的提问来源于stack exchange，提问作者user7104332