PHphillmv·Jun 25, 2013Recommendation phrase
Hello!
I have performed two rails 2 upgrades. Both cases they were smallish apps, but they took 3-5 days to feel comfortable with everything that's happened.
If this is an app that is still being actively developed, I highly recommend you fast track it.
[If not, look up the community-managed security back port branch and switch to that asap]
Basically, the problem stems from bit-rot and alas such is the nature of our industry. In a nutshell, the longer you wait the harder it is to find quality docs on what's changed and how to fix it. A lot of links are now gone.
The main challenge comes from: the change in the router, the changes in the view api (everything is escaped by default, and you will find a ton of string concats in your helpers that will now spit out garbage), migrating over to the asset pipeline (which I personally found confou
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nding for a long time until I got the hang of it), migrating over to Arel queries and updating all of your plugins - many of which will stop working in quirky ways. You may also experience pain with updating your test suite.
So, there's a lot of yak shaving but you don't actually have to refactor your app much. Your controllers will remain basically untouched and so will your models modulo named scopes and certain now preferred validation patterns. Most of the pain is view-focussed.
Oh, and the attribute protection but that pain is a good pain, you really need to whitelist your attributes. IF YOU ARE READING THIS MAKE SURE YOUR MODELS HAVE AN `attr_accessible` THAT DOES NOT HAVE ANY ATTRIBUTE THAT ENDS IN `_id`.
There's a phenomenal plugin that will help a lot - https://github.com/rails/rails_upgrade - but it's not going to catch everything.