[UX] Revamp the confirmation pages for updating module/themes/layouts

[klonos]

Description of the need

1. Head to /admin/modules/update
2. Select an update, and click on the "Download these updates" button...

Here's what the confirmation page currently looks like:

Proposed solution

• Make "Back up your database and site before you continue" a proper warning
• Add a "Cancel" button

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PR by @klonos: backdrop/backdrop#2804

[klonos]

...while at it, I have updated the "Learn how" link to point to https://backdropcms.org/upgrade instead of the current http://drupal.org/node/22281 😉

I am wondering if we should have some sort of constant for the message, so that it can be reused (in places like #512 for example). This would also make it so that translators translate things in a single place, and we update this message in a single place in the future if need be.

[stpaultim]

Can you add a quick comment on how to test this? I assume I can't do it in Sandbox.

Concerned with finding the easiest way to simulate an upgrade situation

[klonos]

I assume I can't do it in Sandbox.

Yes you can 🙂 ...just head to Functionality -> Update modules (/admin/modules/update) ...there is currently a known (useful in this case) bug which lists the current stable release (1.13.2 at the time of writing this) as an update of the current dev release (1.14.x-dev). Simply tick the checkbox next to Backdrop core, and click the "Download these updates" button ...once the download is complete, you should be taken to this page 😉

[klonos]

...note: we could use a "Cancel" link in this form, but we need to account for destination, so that the user is taken back to the page where they started (modules/themes/layouts updates) ...is that out of scope for this issue, or can we sneak that in while at it?

[klonos]

Adding the proper link/redirect to the "Cancel" button turned out to be trickier than expected...

Setting $_GET['destination'] on the submit handler for installer_manager_update_form_submit() dit not work, as that was blanked by the time you reach installer_manager_update_ready_form() (I am guessing that the batch has something to do with that).

I have also tried appending the destination to the form action via a $form['#action'] .= '?destination=' . drupal_get_destination();, but that did not work either.

I then also tried setting 'url_options' => array('query' => array('destination' => 'admin/modules')), in the batch definition array, but that does not seem to work either 😞

I ended up storing the project type in $_SESSION instead, which works.