Question

I have complex data structure, like this: OrderedHash, keys are dates and values are ordered hashes which hold integers with string keys. I need to serialize those in order to store in db. But after to_yaml/YAML.load data is sometimes broken — some of second-level hashes are replaced with first-level or vice-versa. Sometimes it is not broken, though.

yaml representation looks like this

- 2011-07-10: !omap 
    - 00:00-01:00: 0
    - 01:00-02:00: 0
    - 02:00-03:00: 0
    - 03:00-04:00: 0
    - 04:00-05:00: 0
    - 05:00-06:00: 0
    - 06:00-07:00: 0
    - 07:00-08:00: 0
    - *id010
    - 09:00-10:00: 0
    - 10:00-11:00: 0
    - 11:00-12:00: 0
    - 12:00-13:00: 0
    - 13:00-14:00: 0
    - 14:00-15:00: 0
    - 15:00-16:00: 0
    - 16:00-17:00: 0
    - 17:00-18:00: 0
    - 18:00-19:00: 0
    - 19:00-20:00: 0
    - 20:00-21:00: 0
    - 21:00-22:00: 0
    - 22:00-23:00: 0
    - 23:00-23:59: 0

This *id010/&id010 part gets randomly inserted in different places of yaml code. I think it’s the cause of error.

Does anybody have the idea of what is wrong with yaml serialization?
ruby 1.8.6, upgrade to 1.9 isn’t an option 🙁

Answer 1

It’s very possible there is a bug. I believe the YAML engine Ruby 1.8 uses is called Syck, and this code was created by _why many years ago. The code has not been properly maintained since then.

Ruby 1.9 is supposed to use a new engine called Psych, but I am not sure how compatible this is with Ruby 1.8.

On Github I also found another alternative, which looks like it might be worth a try for you:
https://github.com/cesare/ruby-libc-libyaml

Syck (you might try this version, since it looks like it’s being semi-maintained):
https://github.com/indeyets/syck

Psych (you could also try and see if this runs on 1.8):
https://github.com/tenderlove/psych

---

EDIT

Perhaps JSON could be an alternative for you also? Take a look at the to_json method and see if that could be used for your purposes, and perhaps circumvent the YAML problems this way.