ENH Restore gridfield state from get vars (POC)

[GuySartorelli]

The GridFieldDetailForm's item edit form adds the current gridfield state to the URL of the CMS breadcrumbs back button (not the browser back button).
This PR pulls that state back into the GridField, so that when a user clicks back they retain the pagination and filter options they had set.

Parent Issue

• Navigating back from a record in a GridField doesn't respect selected pagination or filters #9380

Why this is draft

The GridField is a complicated beast, and apparently there are a few issues related to this one which ideally should be addressed in tandem. Also, trying to resolve this is taking a lot longer than I expected, so I'm parking this for now.
Note that this PR is not complete - for this functionality to be reliable we would need to make the following additional changes:

• Add the state to the GridFieldViewButton's URL
• Check why sometimes the GridFieldEditButton doesn't include the state and decide if it should do so
• Add javascript to admin in GridField.js in the onmatch event to make the search filter visible if the state indicates that the field has been filtered
• Consider using window.history.replaceState() in admin javascript to add the gridfield state to the current history when the state changes (i.e. when paginating or filtering a gridfield)

Related PR

• ENH Keep State and show Search field if any keywords are presented silverstripe-admin#1326

[sabina-talipova]

Hi @GuySartorelli ,

Are you planning to continue work on this task? Or do you want me to finish it?
Thank you.

[GuySartorelli]

@sabina-talipova I'm not going to take this any further at this stage. I think we need to take a step back and look at how the state for gridfield is being managed more generally - as mentioned in my last comment there are quite a few issues with gridfield state which point to a deeper problem than this PR is equipped to resolve.

[GuySartorelli]

This doesn't seem to work at all for relations in a gridfield on a page. e.g. try adding some relations to the "has many" or "many many" tabs in the "GridFieldTestPage" created by framework test.
Seems to work okay for gridfields in a model admin, but doesn't have browser back/forward support - I assume you're holding off on that part until we have some UX advice on how that should behave?

[GuySartorelli]

There's no code in here or in the companion admin PR to actually set the gridfield state to the URL when you perform some action (i.e. paginate or filter) - so the state is only appended to the URL for the GridFieldEditButton specifically - and that's only there to support the breadcrumb back button.
This means that GridFieldViewButton for example has no state attached to it, which means breadcrumb back buttons for view-only forms won't return you to the state you were in. It also means I can't copy the URL to a new tab and keep my state in that new tab.

The following ACs from the issue are therefore not met:

• When you perform an action in the gridfield, it updates the URL.
  Currently the state is not in the URL except when you click on a GridFieldEditButton and then on the back button in the breadcrumbs
• The browser history is hijacked so that the back/next button can be use to navigate your gridfield state.
  I assume you're waiting for the UX advice on this, so that is fine for now

Interestingly there's no AC for the breadcrumb back button, but there probably should be.

[sabina-talipova]

There's no code in here or in the companion admin PR to actually set the gridfield state to the URL when you perform some action (i.e. paginate or filter) - so the state is only appended to the URL for the GridFieldEditButton specifically - and that's only there to support the breadcrumb back button. This means that GridFieldViewButton for example has no state attached to it, which means breadcrumb back buttons for view-only forms won't return you to the state you were in. It also means I can't copy the URL to a new tab and keep my state in that new tab.

The following ACs from the issue are therefore not met:

• When you perform an action in the gridfield, it updates the URL.
  Currently the state is not in the URL except when you click on a GridFieldEditButton and then on the back button in the breadcrumbs
• The browser history is hijacked so that the back/next button can be use to navigate your gridfield state.
  I assume you're waiting for the UX advice on this, so that is fine for now

Interestingly there's no AC for the breadcrumb back button, but there probably should be.

To keep State in URL after user click on search or sort fields, I had to make changes in GridField.js. All this changes in other PR: silverstripe/silverstripe-admin#1322

[GuySartorelli]

In GridFieldDetailForm_ItemRequest::getBackLink() change the return statement to this:

return $this->gridField->addOtherGridfieldStateToURL($backlink);

That way we don't have to do that in LeftAndMain or CMSMain etc.

[GuySartorelli]

There's a failing unit test - other than that it looks good.

[sabina-talipova]

@GuySartorelli, actions failed on unrelated to my changes test cases. Should I fix them?

[GuySartorelli]

No, you can ignore that for this PR. It should be fixed separately. It looks like it was caused by a bad merge up from CI PRs, so Steve or I will look at it as part of the CI migration work

[GuySartorelli]

Failed unit test is unrelated.

[GuySartorelli]

I can't click "approve" since I originally opened this PR - so consider this message to be approval.