Ruby On Rails: How can I sort this hash by its keys in descending order

(rdb:60) p resultsHash
{ 1 => [#<Participant id: 6, username: "player2", online_rank: 7, created_at: "2011-05-14 04:49:22", updated_at: "2011-05-14 04:57:56", win_count: 1, device_type: "iPad">], 
  0 => [#<Participant id: 5, username: 开发者_开发百科"player1", online_rank: 3, created_at: "2011-05-12 02:47:50", updated_at: "2011-05-12 02:47:50", win_count: 0, device_type: "iPad">, 
        #<Participant id: 4, username: "iPhone4Simulator", online_rank: 4, created_at: "2011-05-12 02:45:37", updated_at: "2011-05-12 02:45:37", win_count: 0, device_type: "iPad">]}

I've tried...

resultsHash.sort {|a,b| -(a[0]<=>b[0])}

but the results aren't sorted by the keys when I iterate through the hash using each_pair.

Thanks!

What you really want to do is add an ORDER BY clause to your query. If this is Rails 3, Participant.order(:id).all is one way to do it.

To answer your immediate question, though, you would say resultsHash.sort_by(&:id). But don't do it this way.

Side note, use snake_case for Ruby code, not camelCase.

Edit: See comments.

resultsHash.sort.reverse

Note that it'll return an Array of [key, value] pairs. But you can still iterate like with a Hash:

resultsHash.sort.reverse.each do |key, value|
  ....
end

Or you can retrieve only the values: resultsHash.sort.reverse.map { |key, value| value }, or resultsHash.sort.reverse.map(&:last)

I realize this is an old question, but one way you can do exactly what you want while still retaining a return type of Hash is to use .slice on the sorted keys:

resultHash.slice(*resultHash.keys.sort)