Searching items with (ManyToMany+something else) relations

[SZEKERES Istvan]

Hi,

This is a simplified example about what I want to do. There are
restaurants, they have categories (e.g. pizzeria, vegetarian, etc.) and
a city the restaurant is in.

I have the following model (simplified):

class Category(meta.Model):
        ...

class City(meta.Model):
        ...

class Restaurant(meta.Model):
        ...
        categories = meta.ManyToManyField (Category)
        city = meta.ForeignKey (Place)

i.e. a restaurant can belong to several categories, but has only one place.

Now how can I select all the restaurants that belong to a category and are
in a given city?

To get the restaurants from a city I can do:
  r = restaurants.get_list (city__id__exact=n)

To get the restaurants belonging to a specific category I can do:
  r = category.get_restaurant_list()

But is there a way to combine them? Comparing the results of the two
queries to find the common items is not very optimal... I'm looking for
something like 

  r = restaurants.get_list(city__id__exact=n, categories__contain=category)


Thanks in advance,
Pistahh/freenode