Add config.horizontal_scroll_list to enable horizontal scrolling colu…

[sbull]

…mns and frozen row headers instead of paginated sets

Addresses Issue #2272.

[sbull]

Hi @mshibuya, I've created this PR due to interest from Issue #2272 and I've updated the wiki https://github.com/sferik/rails_admin/wiki/Horizontally-scrolling-table-with-frozen-columns-in-list-view to describe it. Hopefully this can make it into a release.

The current Travis failures seem unrelated to this PR - "unable to load puma" on other test cases.

[mshibuya]

Great work, but there's a few things to consider.

[sbull]

Thanks for your feedback!

1. I had wanted to make this as low-impact as possible, so that the JS & CSS wouldn't even be loaded in the default configuration. If these are in separate files, I don't think it's possible to conditionally load them (assuming the right thing would be to make them part of the asset precompile pipeline)? But I can submit a change to do it the "right" way.

2. I expect that the most-used config will be global options, but I will look into making it work per-model as well.

3. I'll look into moving some of the calculation logic into the config class or helpers.

I hope to put some time into this in a few days. Thanks again!

[sbull]

Hi @mshibuya, I've refactored this code to address your requests

1. Move JS & CSS into asset files.
2. Enable configuration at model level.
3. Move config logic out of view.

I've reworked the tests to account for these changes, and created new tests to check the model-level configuration. I've also rebased this PR. I can squash these commits if you'd like but I thought I'd leave them separate for now for you to review the changes from the original PR.

Let me know if other changes are needed. I don't really know how to fix the codeclimate "cognitive complexity" issue - perhaps split it up into multiple methods, but that seems like it could result in a fair amount of duplicate code.

Thanks!

[sbull]

Hi @mshibuya , I was wondering if you could take a look at this, as it's been open for a while. Thanks!

[mshibuya]

Thanks you for amazing work!
I'm planning to change the name of this feature to sidescroll.

[twikah]

Hi @mshibuya, thanks for getting this merged! Are you planning on making a release soon? It would be great!