Django QuerySet.union（）-或QuerySet.raw（）实现不区分大小写的Mutli-Search

Question

Given a URL like this:

http://..../search/?foo=a&foo=B&bar=whatever

In my View, I want to filter the QuerySet for CASE-INSENSITIVE matches of "foo". There's a handy "in" operator that I could use on my list of "foo", but it doesn't support case-insensitivity.

To be clear, this (elegant code) performs a CASE-SENSITIVE match. (It doesn't match "foo=b".) I do not want this:

    queryset = queryset.filter(foo__in=role)  # case-sensitive

My solution is to create a list of QuerySets, one for each "foo" match, and then to create return a final "union()" of the results.

def get_queryset(self, **kwargs):
  queryset = super(PeopleListView, self).get_queryset()

  foo = self.request.GET.getlist('foo')
  if (len(foo) == 1):
    queryset = queryset.filter(foo__iexact=role[0])  # case-insensitive
  elif (len(foo) > 1):
    qs_list = []
    for _foo in foo:
      qs_list.append(queryset.filter(foo__iexact=_foo))
    queryset = Person.objects.none()  # EmptyQuerySet
    for qs in qs_list:
      queryset = queryset.union(qs)

  bar = self.request.GET.get('bar')
  if bar is not None:
    queryset = queryset.filter(bar__iexact=bar)  # Easy

This results in an error:

django.db.utils.DatabaseError: ORDER BY not allowed in subqueries of compound statements.

Is there a way to do this with "Q" objects?

If not, I think the "right" solution would involve converting the match patterns to lower-case, then using QuerySet::raw() to convert the database values to lower-case as well. I'm a bit over my head there...

Thanks for your help!

Answer 1

Well, here's the answer. Use "Q" objects! :-)

...
foo = self.request.GET.getlist('foo')
if (len(foo) > 0):
  q = Q()
  for _foo in foo:
    q |= Q(foo__iexact=_foo)
  queryset = queryset.filter(q)
...

Oh, and to support matching URLs like this:

http://..../fl/users/?foo=&bar=some_bar

which makes:

<QueryDict: {'foo': [''], 'bar': ['some_bar']}>

I'll do this:

...
foo = self.request.GET.getlist('foo')
if (len(foo) > 0):
  q = Q()
  for _foo in foo:
    if (_foo == ''):
      q |= Q(foo=None)
    else:
      q |= Q(foo__iexact=_foo)
  queryset = queryset.filter(q)
...