provide cache digest for view

[ermolaev]

fix if changed view, cache not expired

but, I think dynamicly modify view_context.lookup_context.view_paths bad for perfomance

#234

[BlakeWilliams]

Is it possible to do this at the Railtie level instead of the component level?

I'm a little concerned about performance since this would run at least once per-component render.

[ermolaev]

I cached lookup_context in class attribute, bun it work only rails 6.0, 6.1, older versions is a hard work for support

[joelhawksley]

@ermolaev thank you for the PR!

I think we need to work to find a solution that works consistently across our supported Rails versions (>=5). I'm wary of introducing incomplete support for caching in the manner proposed by this PR.

I recognize that this is probably not the answer you wanted to hear, and that taking on caching support for ViewComponent is no small effort, but I hope you agree that we need to take the time to do this right ❤️

[stevehodgkiss]

This looks like it's almost there for Rails 6! It works for cache blocks with no dependencies, but with dependent view components the dependency tracker in ActionView fails find them. For example, with <%= render Shared::Something.new %> inside cache "key" do it logs "Couldn't find template for digesting: Shareds/Shared". To properly digest templates with dependencies, an extension or replacement of the ERB tracker in ActionView::DependencyTracker is probably needed, to return template paths for view component render calls.