Querying datastore for all models that contain a certain element within a listproperty

Hey, I have a model like this:

class List(db.Model):
    user = db.ReferenceProperty(User)
    listname = db.StringProperty()
    published = db.DateTimeProperty(auto_now_add=True)
    score = db.IntegerProperty(required=False)
    tld = db.StringProperty(required=False)
    categories = db.StringListProperty()

Where a list could have multiple categories attached to it (hence the listproperty). I want to use these categories to build category pages so I need a query I can use to fetch all lists that have a particular category within their categories attribute. I've tried a few different approaches and none seem to work. Is there a query like this this? (the following doesn't work):

selec开发者_JS百科t * from List where 'Philosophy' in categories

If not, I'm going to have to do something like:

lists = List.all()
for list in lists:
    if 'Philosophy' in list.categories:
        #add this list to the lists to display on page

But this feels like it would be either incredibly slow or break somehow...

Any ideas? Thanks!

Tom

UPDATE:

Oops, I solved it sorry for the bother! For anyone who's interested you can just use a query like this:

SELECT * FROM List where categories = 'Philosophy'

Which will match any list which has 'Philosophy' within the categories.

Oops, I solved it sorry for the bother! For anyone who's interested you can just use a query like this:

SELECT * FROM List where categories = 'Philosophy'

Which will match any list which has 'Philosophy' within the categories.