Question

So I’ve got a SQL query I’d like to duplicate in rails:

select g.* 
from gamebox_favorites f 
inner join gameboxes g on f.gamebox_id = g.id 
group by f.gamebox_id 
order by count(f.gamebox_id) desc;

I’ve been reading over the rails Active Record Query Interface site, but can’t quite seem to put this together. I’d like the query to return a collection of Gamebox records, sorted by the number of ‘favorites’ a gamebox has. What is the cleanest way to do this in rails?

Answer 1

I believe this will work (works on a similarly structured database locally), though I’m not sure I have the proper models in the proper spots for what you’re trying to do, so you might need to move a coule things around:

Gamebox.joins(:gamebox_favorites).
  group('"gamebox_favorites"."gamebox_id"').
  order('count("gamebox_favorites"."gamebox_id")')

On the console, this should compile to (in the case of PostgreSQL on the back end):

SELECT "gameboxes".* FROM "gamebox_favorites" 
  INNER JOIN "gamebox_favorites" 
  ON "gamebox_favorites"."gamebox_id" = "gamebox"."id" 
  GROUP BY "gamebox_favorites"."gamebox_id" 
  ORDER BY count("gamebox_favorites"."gamebox_id")

…and I’m guessing that you don’t want do just wrap it in a find_by_sql call, such as:

Gamebox.find_by_sql("select g.* from gamebox_favorites f 
  inner join gameboxes g 
  on f.gamebox_id = g.id 
  group by f.gamebox_id 
  order by count(f.gamebox_id) desc")