ENH Update page number in the state on reaching the first or the last…

[sabina-talipova]

Description

Update page number in the state on reaching the first or the last element in a list.
Keeping state in "better button" href for getting new set of elements after user reaches last or first element on a page by using navigation GridField Item.

Parent issue

• GridField. Better button issues. silverstripe-admin#1315

[GuySartorelli]

The overall approach looks good. I haven't tested this locally but it seems to make sense.
Couple of small changes - though note I was only looking at this from a "is the approach reasonable" point of view for now since it is in draft.

[GuySartorelli]

State issues

It doesn't looks like this works as expected - for example if I am on the test modeladmin and I search for "i" and go to page 3, then click on the top item and click previous, the link for the breadcrumb back button still takes me to page 3 instead of page 2. This video shows that happening:
PR doesn't solve issue
Looks like there are a few old bits of code getting in the way here, where the changes to gridfield state are being overridden by whatever is in the request:

• delete these lines as this is done by GridField::addStateFromRequest() already
• change these lines to $gridState = $this->gridField->getState(false);.

Move the logic

I know I said the approach was good, but I have since noticed that this can be called from getPreviousRecordID() and getNextRecordID() which are both public methods.
Please move the logic you added from getAdjacentRecordID() into the top of edit() - that way it should only happen when someone actually visits the form, not when calling public methods.

[GuySartorelli]

Also the PHPlinting CI job has failed.

[GuySartorelli]

Looks good and works locally. Just a small change still outstanding from a previous review.