We might need to upgrade to webpack first before upgrading to Rails6. Here are some instructions to use Rails6 without webpack, but they seem to include some manual steps:

https://stackoverflow.com/a/58518795/2110884

Here are some instructions on how to use webpacker with Rails engines:

https://github.com/rails/webpacker/blob/master/docs/engines.md

Affected modules seem to be those that hand JS files in their vendor folders:

• decidim-core
• decidim-admin
• decidim-api
• decidim-accountability

I managed to create the test app properly, but it's failing whenever it tries to load any class or module within Decidim::Messaging

I fixed some classnames/filenames thanks to bin/rails zeitwerk:check, but it's still failing whenever trying to load anything from Decidim::Messaging:: and I don't understand the cause of the issue.

Looks like I managed to solve the Decidim::Messaging:: classes issue, but now it's complaining due to assets. It might be a better approach if we just start moving the assets to webpacker, and then try to upgrade to Rails 6.

@mrcasals , I have dug for the last few days in that rails 6 upgrade, and i think that Decidim is not ready yet for that ...

I have got into the same issue with the webpacker ( meaning that i have installed, but somehow the assets are getting messed up ) (Implementing the suggestion with webpacker in gem, i got into a strange situation when main/development app, tried to load assets from decidim. in my endeavors i have not been able properly load decidim packs in main app, nor provide a parameter that would specify the module / pack where the asset is located ) (edited)

from what i have seen, DHH stated that webpacker and sprockets can work together, after digging for about 2 days ... i could not find a way around that , so i have managed to look into other engines that are out there, and i have seen that they are using the assests pipeline ( sprockets )

From my investigations, in order to successfully upgrade to rails 6, we need to remove that sprockets-es6 compatibility (please read details here https://github.com/TannerRogalsky/sprockets-es6#asset-manifests-required-for-precompiling ) (edited)

Downgrading sprokets ... may work, however, new issues will be encountered with some other assets ( that can be added to the pipeline), but there is an issue with decidim/foundation ( and possible all other )

Some other issues willl be in the Graphql part

Query is invalid: Query must define at least 1 field. 0 defined.

and this is even more interesting ... Duplicate type definition found for name 'User' at 'User' (User, User) , and i see a resolution here ... rmosolgo/graphql-ruby#935 (edited)

@alecslupu For the GraphQL duplicate type defintions, see #4202.

Decidim is currently also using the legacy type definition format with graphql-ruby. It might help to update to the new class-based API.

@ahukkanen I am already working on the GraphQL upgrade ... I am currently trying to resolve the 152 failing tests i have on the Core module /...

Additional work is done in #6871

@alecslupu Great, nice!

Thanks @alecslupu for helping here! The GraphQL thing is a long-overdue refactor!

As I mentioned previously, I think the best way to upgrade to Rails 6 will be to first move all the assets to webpacker (thus gaining some benefits, like being able to use modules and dropping the vendor folders), and then trying to upgrade to Rails6

Closing in favor of @alecslupu's work

Closed in favor of #7086