Question

I’m aware of full text search applications like Django Solr and solango, etc.

What I’m looking to built is more akin to an advanced search for a real estate site.
E.g they can choose location, price, etc. similar to http://www.viewr.com advanced search.

What I have done so far is this, under the models custom manager:

def advanced_search(self, district, location, type, facilities, features, not_permitted):
        q_objects = []
        l_objects = []
        t_objects = []
        fc_objects = []
        ft_objects = []
        np_objects = []

        if district:
            if location:
                for loc in location:
                    l_objects.append(Q(location__exact=loc))
            else:
                l_objects.append(Q(location__district=district))


        if type:    
            for ty in type:
                t_objects.append(Q(listing_type__exact=ty))

        if facilities:    
            for fc in facilities:
                fc_objects.append(Q(property_facilities__exact=fc))

        if features:
            for ft in features:
                ft_objects.append(Q(property_features__exact=ft))
                ft_objects.append(Q(community_features__exact=ft))

        if not_permitted:    
            for np in not_permitted:
                np_objects.append(Q(not_permitted__exact=np))                              

        # Start with a bare QuerySet
        qs = self.get_query_set()

        if location:
            qs = qs.filter(reduce(operator.or_, l_objects))
        if type:
            qs = qs.filter(reduce(operator.or_, t_objects))
        if facilities:
            qs = qs.filter(reduce(operator.or_, fc_objects))
        if features:
            qs = qs.filter(reduce(operator.or_, ft_objects))
        if not_permitted:
            qs = qs.filter(reduce(operator.or_, np_objects))
        # Use operator's or_ to string together all of your Q objects.
        return qs

Right now I’m not getting very predictable results. Is there something I might be doing wrong? Is there a better way of doing the various OR searches/joins?

Answer 1

The closest I’ve come to this scenario is this post by Jacob:

http://www.djangosnippets.org/snippets/32/

What I’ve done is:

def advanced_search(self, form):
        # It's easier to store a dict of the possible lookups we want, where
        # the values are the keyword arguments for the actual query.
        qdict = {'district': 'location__district',
          'location': 'location',
          'property_type': 'listing_type',
          'max_price': 'price__lte',
          'property_features': 'property_features',
          'community_features': 'community_features',
        }

        # Then we can do this all in one step instead of needing to call
        # 'filter' and deal with intermediate data structures.
        q_objs = [Q(**{qdict[k]: form.cleaned_data[k]}) for k in qdict.keys() if form.cleaned_data.get(k, None)]        
        search_results = RealEstateListing.objects.select_related().filter(*q_objs)
        return search_results

It works fine when I pass single choices, but when passing multiple choices as for property facilities it chokes and says:

OperationalError: Subquery returns more than 1 row