为什么 heroku 会改变哈希的顺序？

Question

for the life of me i could not figure this out.

if i have this in my local dev/production:

fields = {:name => {...}, :description => {...}, :amount => {.... } }

its fine i loop through my hashes and print the fields name just like how i declared it.

In heroku, the sequence is different in printed order?? I have complete no idea why and i can't get a clue why heroku is printing them in different order.

does that make sense?

Edit: OMG its driving me nuts. I actually do this in my templat, sorting my variable but For some reaaaaaly weird reason, its still coming out in a manner heroku only understands.

- @form_columns = @form_columns.sort_by do |i| 
  - if i[1][:rank].nil?
    - i[1][:rank] = rank
  - i[1][:rank]  
  - rank = rank + 1 

This is how i loop by the way:

• @form_columns.each do |column_name|

Please understand that there is no issue in my local production/dev server.

Answer 1

The order of keys within a Hash is not guaranteed to equal the order in which were inserted, in Ruby 1.8

That behaviour is different in Ruby 1.9, where the order is preserved.

http://www.igvita.com/2009/02/04/ruby-19-internals-ordered-hash/

Are you using ruby 1.8?

Answer 2

If you for some reason have to use Ruby 1.8 then you can get an ordered hash by using OrderedHash in Rails ActiveSupport .

To see what stack you are using on Heroku:

heroku stack

and to migrate to 1.9.2:

heroku stack:migrate bamboo-mri-1.9.2