update gem version that is specified in another gem dependency

Question

In my Gemfile, I'm including a gem that has a .gemspec that uses the pessimistic operator ~> to specify a version of the gem. However, I need to use a newer version of the gem. In my case I'm using spree 3-0-stable that has activemerchant set to '~> 1.47.0' https://github.com/spree/spree/blob/3-0-stable/core/spree_core.gemspec#L22 but I need use active merchant '~> 1.59.0'

I tried to specify version 1.59.0 in my Gemfile but bundle complains with:

You have requested: activemerchant ~> 1.59.0

The bundle currently has activemerchant locked at 1.47.0. Try running bundle update activemerchant

If you are updating multiple gems in your Gemfile at once, try passing them all to bundle update

But the command bundle update activemerchant will only update to 1.47.x.

What's the rails-y way of accomplishing this? Aside from forking spree myself and updating the .gemspec? Obviously updates to the activemerchant gem might break the spree gem. But I can test with my app.

Answer 1

The maintainers of Bundler have recommended forking the relevant gem, then making a PR back onto the gem. Then link directly to the branch in that PR in your Gemfile. This encourages the community to rally around a solution.

I've documented the process in detail here: https://github.com/rubygems/rfcs/pull/13#issuecomment-770416467

Answer 2

You can't do it, the rubygems system doesn't allow that. You have to file an issue for the upstream gem dependency, and ask them to loosen their requirements.

It may be that the version of activemerchant you want actually won't work with the version of spree you want, it will break it. If so, spree code would have to be fixed to work with the new version of activemerchant. Or, it could work fine with the version you want, the restriction in spree is accidentally unneccesarily strict, in which case the spree gemspec would just have to be changed to allow it.

But there's no way for you to override it without changing the spree gemspec.

You could make your own fork of spree in which you change the gemspec -- but without knowing whether or not spree will really work with the version of activemerchant you want, that could be dangerous. And now you're on your own fork, so you won't be able to upgrade to new versions of spree without merging in their changes to your fork, etc.

Another thing is, it's a bit odd to be running off a spree 3-0-stable branch, instead of an actual released version of the gem. But I'm not familiar with spree's release management practices, perhaps this is what they encourage? At any rate, changing this probably won't fix your problem.

If your app is relatively new or simple, you could consider switching from spree to solidus, a fork of spree. Solidus forked off at spree 2.x though, so migration from spree 3.x might not be straightforward, especially if your app is established and somewhat complex. Although the solidus_core gem is also locked to activemerchant ~> 1.48.0, so it also won't allow anything but activemerchant 1.48.x. The solidus team is pretty responsive on their Slack channel, if you wanted to ask them what's up with that, if they know if later versions of activemerchant will work, if the dependency can be loosened. I have found the solidus maintainers to be very responsive, and likely to be interested in allowing later versions of activemerchant if it's feasible to do. I'm not familiar with the current Spree team and how they communicate with users (if they have a slack, or listserv, or are responsive on github issues, or what), but you could of course have the same conversation with them.