Re: Cuirass enhancements

[Danny Milosavljevic <dannym@scratchpost.org>]

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Hi Björn,

On Tue, 18 Jun 2019 19:50:25 +0200
Björn Höfling <bjoern.hoefling@bjoernhoefling.de> wrote:

> * I would like to know that I'm on page k/n.

That web interface is a frontend to a dynamically changing database
(and a quickly changing database at that).

What would "page" even mean there?

And the "/n" part is impossible to keep constant because the database changes
and so does n.
So the "/n" part on the display would keep changing--and it would be correct
in doing so.  Furthermore, the page number you are *on* would also keep
changing.

Even if there were fixed-layout "page"s, the way the database is
structured means that having pagination show a fixed number of items
per page at all is difficult to do (cuirass tries to do it).

Alternatively, the server could keep a serializable transaction
open per client session.
Then you just wouldn't see new builds until you somehow restarted your
client session (HTTP is stateless--so more fakery necessary there).
Then you can have page numbers :)

> I'm at the first tab. "Previous" is greyed out.

I don't like this graying out business.  It's perfectly possible that a new
entry appeared in the database that is now (because of the sorting) before what
you thought was the first page (because back then when you queried the page it
*was* the first page--emphasis on "was")--and now you can't get to it.

> Then I would expect
> "First" also to be greyed out: If I cannot go any further back, I am on
> the "First" tab (linear, consecutive order of tabs assumed :-))

I've made "First" and "Last" behave the way you expect in cuirass commit
d5b827097b456100039370003899ec7ad04ac934.  However, that is not
an endorsement of graying out.  I just like consistency.
 
> Even worse at the end: I can click four times on "Next", and then be at
> a page that shows only three jobs (the total number of jobs is not
> always dividable by the number of jobs per page, so the last page
> usually has a smaller remainder to show):
> https://ci.guix.gnu.org/eval/5862?border-high-time=1560816540&border-high-id=1398862
> So, I cannot go any NEXTer, that button is greyed out. As with the
> beginning, I'm expecting to be already on the LAST page. But the button
> is clickable. And when I click it, I will receive a FULL PAGE! 

Yeah, well, pages don't exist and cuirass in imperfectly faking them.

I'd go back to first principles and ask what problem the paging is supposed to
solve, then solve it in a different way.  It's already very different to what
book pages would be.

Suggestions welcome.

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