GridField. Better button issues.

[sabina-talipova]

Description

There is a problem with the "Previous" and "Next" buttons in a child element.

• Does not navigate past the first two items on the next page when using this navigation to navigate from an item listed on the first page to an item listed on the second page.
• This element does not support filtered and sorted lists.

SPIKE (for context)

silverstripeltd/product-issues#254

AC's

• Once you click on a specific item, it should still keep track of the parent GridField state, so better buttons knows how to filter the list
• When user reaches last item in the GridField list on particular page, except last one, and they click on 'Next' button they should get the first item of GridField list with all applied filters and sorting on the next page.
• When user reaches first item in the GridField list on particular page, except first one, and they click on 'Previous' button they should get the last item of GridField list with all applied filters and sorting on the previous page.
• The last and first item in the gridfield don't loop.

Notes

• When viewing a specific item, it's not clear that it's in a filtered list. Maybe we should have a foolow up card on this.
• Concurrent editing of the Gridifeld will lead to weird results. There's not much we can do about that right now.

Related issue

• Gridfield Better Buttons don't handle sorting and pagination #886

PR's

• ENH Update page number in the state on reaching the first or the last… silverstripe-framework#10439
• ENH Behat test cases for GridField navigation #1338
• NEW Test class for GridField with limited number of items in the list silverstripe-frameworktest#116

[GuySartorelli]

All PRs merged, no outstanding ACs.