Question

Consider the below situation

I have a database table as below

user_id user_rank
------------------
22       10
32        9
43        7
31        6

and i have a JSON Object with the user id like (other nodes in json are hidden for simplicity, consider this response is from an api)

{"user_id":[31,22,43,32]} 

now, how do i sort the JSON result based on the rank of a user_id in database and produce a
result like

{"user_id":[22,32,43,31]}

is there anything like LINQ in rails, so that i can save the json object values in it,
and make join between the object and database table to obtain the sorted json?

Answer 1

If you have user ids in json then :

require 'json'
user_hash = JSON.parse('{"user_id":[31,22,43,32]}') => {"user_id"=>[31, 22, 43, 32]}

users = User.all(:conditions=>["id in ?",user_hash[:user_id]])
sort_user_id = users.sort { |x, y| (x.user_rank|| 0 )<=> (y.user_rank|| 0)}.map(&:id)
{:user_id => sort_user_id}.to_json

Hope that help.