Sometimes you just have to do it yourself, like when you have relationships between different databases.
Here I wanted to retrieve an array of site_ids:
1
2 result = ActiveRecord::Base.connection.execute("SELECT * FROM sites_users WHERE user_id ='#{self.id}'")
3 rows = []
4 result.each_hash {|h| rows << h['site_id'].to_i }
5 return rows
UPDATE: ( An easier, better way)
1
2 rows = ActiveRecord::Base.connection.select_values("SELECT site_id FROM sites_users WHERE user_id ='#{self.id}'")
3 return rows.map {|el| el.to_i }
There is also:
select_one(sql, name = nil)
select_value(sql, name = nil)
select_all(sql, name = nil)