动态编写 django 过滤器

Question

I have a Django filters for couple of models. but they both have same filtering how to make it DRY.

class TestFilter(django_filters.FilterSet):
    field_list = Test._meta.get_fields()
    for field in field_list:
        field_name = (field.__str__().split('.'))[-1]

    if type(field) is model.CharField:
        field_name__contains = field_name + '__contains'
        vars()[field_name] = django_filters.CharField(field_name=field_name, lookup_expr='iexact')
        vars()[field_name] = django_filters.CharField(field_name=field_name, lookup_expr='icontains')


    class Meta:
        model = Test
        fields = '__all__'


class Test2Filter(django_filters.FilterSet):
    field_list = Test2._meta.get_fields()
    for field in field_list:
        field_name = (field.__str__().split('.'))[-1]

    if type(field) is model.CharField:
        field_name__contains = field_name + '__contains'
        vars()[field_name] = django_filters.CharField(field_name=field_name, lookup_expr='iexact')
        vars()[field_name] = django_filters.CharField(field_name=field_name, lookup_expr='icontains')


    class Meta:
        model = Test2
        fields = '__all__'

both classes have same code. I tried to move code part in utils like generic_filter function and import the function to filters file but filters are not working.

Answer 1

You should be able to write a factory function that returns a class. A class can be defined by use of the 3-argument form of type . I didn't completely understand the use of field_name__contains either. The posted code clearly has an indentation bug.

This is off the top of my head and completely without debugging of any sort

Last time I wrote something like this, by the time I got it working I regretted having bothered. However, it may have been a learning experience. If you are cranking these things out by the dozen, it may be worth your while. Otherwise this may be a case for the other sort of DRY (DO Repeat Yourself)!

def FilterFactory( model_class, class_name):

    class_vars = {}

    field_list = model_class._meta.get_fields()
    for field in field_list:

        field_name = (field.__str__().split('.'))[-1]
        if type(field) is model.CharField:
            field_name__contains = field_name + '__contains' 
            class_vars[field_name] = \
                django_filters.CharField(field_name=field_name, lookup_expr='iexact')
            class_vars[field_name+'_contains'] = \
                django_filters.CharField(field_name=field_name__contains, lookup_expr='icontains')

    class_vars['Meta'] = type( 'Meta', (object, ), {
       "model": model_class,
       "fields": "__all__"
        }
    )

    klass = type( class_name, (django_filters.FilterSet, ), class_vars )
    return klass

Usage

TestFilter = FilterFactory(  Test, 'TestFilter')