What's the best method to show user his vote type (for/against/abstain) on page with lots of post items?
direct query is
SELECT vote_type FROM votes WHERE post_id = 888 AND user_id = 888
and direct way with rails
post.votes.where(:user_id => current_user.id).pluck(:vote_type).first
but it's too heavy and stupid to make db query for every post.
I can build array of posts_id and make one query
@posts.each do |post|
ids << post.id
end
votes = Vote.select(:post_id, :vote_type).where(:user_id => current_user.id, :post_id => ids)
SELECT post_id, vote_type FROM votes WHERE user_id = 888 AND post_id IN (887, 888, 889)
Is there built-in "magick" methods in rails? I use postgresql.
UPD +1 same write method
current_user.votes.find_by_post_id(post.id)
How about
votes = Post.
joins(:user).
joins("LEFT JOIN votes ON votes.post_id = posts.id AND votes.user_id = 1").
select("posts.id, posts.title, users.id AS users_id, votes.vote_type")
with a
votes.map {|p| [p.id, p.title, p.users_id, p.vote_type] }
I get
[[1, "Say hello", 1, nil], [2, "Amazing world", 2, 1]]