Question

I m working on a custom Django Admin FilterSpec (covered already on SO #991926). My FilterSpec is a replacement for the default filter on ForeignKey(User), and basically replaces the list of all users with three only choices, all, mine, and others.

For example, if I applied the custom filterspec to the field created_by it would add an admin filter with All, Created by Me, and Created by Others. Everything works except the negative filter, Created by Others.

I ve been attempting to achieve this by appending __not to the query as so:

def choices(self, cl):
    yield {
             selected : self.lookup_val == self.user.pk,
             query_string : cl.get_query_string({ %s__not  % self.field.name: self.user.pk}),
             display : capfirst( %s Others  % self.field.verbose_name)
        }

It doesn t seem that Django supports filtering in the negative like this. I ve also experimented with having it do a __gte and __lte but the filterspec only uses the first one it finds (gte), dropping the other (lte).

Anybody know how to achieve a negative filter like this through a custom FilterSpec?

Answer 1

This feature is not part of the Django code yet; it is planned for version 1.2. You ll need to apply this patch to the Django code: http://code.djangoproject.com/ticket/5833

Use the get_query_set() method of FilterSpec. For example:

class AlunoStatus(FilterSpec):
    def __init__(self, request, params, model, model_admin):
        self.lookup_val = request.GET.get( exclude_value , None)

    def get_query_set(self, cl, qs):
        if self.lookup_val:
            qs = qs.exclude(field=self.lookup_val)
        return qs

    def choices(self, cl):
        yield { selected : self.lookup_val is None,
                query_string : cl.get_query_string({}, [ exclude_value ]),
                display : _( All )}
        for choice in choices:
            yield { selected : self.lookup_val == choice,
                     query_string : cl.get_query_string({ exclude_value : choice}),
                     display : u"Exclude "+smart_unicode(choice)}

I didn t test this, but I hope you get the idea.

Answer 2

Won t using a "exclude" filter for the negation work?

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