upgrade ruby on rails application

Question

Currently my application run on rails 3.1.3 & ruby 1.9.3.

I want to upgrade my application into rails 4.1 & ruby 2.1

Can anyone tell me how to upgrade the rails application ?

Thanks in advance

Answer 1

There is no specific defined way to upgrade. You can take reference from http://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html or many other blog posts that people have written based on their personal experience. Just google them.

http://www.sitepoint.com/get-your-app-ready-for-rails-4/ https://developer.uservoice.com/blog/2012/03/04/how-to-upgrade-a-rails-2-3-app-to-ruby-1-9-3/

However follow a few points to make it easier. Upgrade one at a time. Better upgrade your ruby first, then rails in second cycle. Do through testing at each step as the gems are likely to fail due to their dependencies. Upgrade you gems manually and avoid bundle update

Answer 2

As addition to @shivam 's answer.

Guides often do not contain all the info. And they often do not say why some steps a necessary.

The most professional way is to read the release notes at least for the next major version. Rails follows semantic versioning, meaning that all following 4.x.x versions are not allowed to introduce breaking public api changes.

Check the Rails 4 Release Notes. Watch out for things marked as deprecated and stuff that was extracted to a separate gem. The best tutorial available is the Upgrading to Rails 4 Screencast.

The most tricky part about the upgrade is the change from protected_attributes in models to strong_parameters in the controllers as a default mechanism against mass assignment protection. If your app already heavily relies on protected_attributes it can be a tremendious task to move this protection outside of the model to every controller. In that case it is recommended to stick with protected_attributes by just including them as extra gem(same name).

In case of the ruby update. You can almost safely update to 2.1.2 from 1.9.3. Ruby follows semver only since Major version 2. If there even have been some incompatibilities since 1.9.3 the probability is very little, that your app used this features. We could upgrade all of our apps from 1.9.x to the last 2.x.x without a single ruby code change