Include with condition, but always show the primary table results - ruby-on-rails

Question

I have a function like :
# get all locations, if the user has discovered them or not
def self.getAll(user)
self.find(:all, :order => 'min_level asc', :include => 'discovered_locations',
:conditions => [ "discovered_locations.user_id = ? OR discovered_locations.id is null", user.id] )
end
self is actually the BossLocation model. I want to get a result set of the bosslocation and the discovered location IF that location was discovered by my user. However, if it was not discovered, i still need the bosslocation and no object as a discovered location. With the above code, if the user has not discovered anything, i don't get the bosslocations at all.
EDIT :
My associations are like :
class BossLocation < ActiveRecord::Base
has_many :discovered_locations
has_many :users, :through => :discovered_locations
class DiscoveredLocation < ActiveRecord::Base
belongs_to :user
belongs_to :boss_location
class User < ActiveRecord::Base
has_many :discovered_locations
has_many :boss_locations, :through => :discovered_locations

Answer 1

I think the problem is that you specify the user_id in the where conditions and not in the join condition. Your query will only give you the BossLocation if the user has discovered it or if no user at all has discovered it.
To make the database query match your need, you could change the include to the following joins:
:joins => "discovered_locations ON discovered_locations.boss_location_id = boss_locations.id
AND discovered_locations.user_id = '#{user.id}'"
BUT, I don't think it would help that much since the eager loading of Rails will not work when using joins like this instead of include.
If I where to do something similar, I would probably split it up. Perhaps by adding associations for user like this:
class User < ActiveRecord::Base
has_many :disovered_locations
has_many :discovered_boss_locations, :through => :discovered_locations
Update:
That way, in your Controller you can get all BossLocations and all discovered BossLocations like this:
#locations = BossLocation.all
#discovered = current_user.discovered_locations.all.group_by(&:boss_location_id)
To use these when you loop through them, do something like this:
<% #locations.each do |location| %>
<h1><%= location.name %></h1>
<% unless #discovered[location.id].nil? %>
<p>Discovered at <%= #discovered[location.id].first.created_at %></p>
<% end %>
<% end %>
What this does is it groups all discovered locations into a hash where the key is the boss_location_id. So when you loop through all boss_locations, you just see if there is an entry in the discovered hash that matches the boss_id.

Answer 2

"a result set of the bosslocation and the discovered location IF that location was discovered by my user."This is not a left outer join.You will get all bosslocations anytime.So,your conditions are wrong!This will get the bosslocation that it's discovered_locations.user_id = user.id OR discovered_locations.id is null".In this condition, this may be difficult for one sql statement. Also you can use union in your find_by_sql,but i suggest you use two find function.