Bug 30017

Summary:	Should we prefer `loop.first` and `loop.last` over calling `variable.count` to reduce our DB hits
Product:	Koha	Reporter:	Martin Renvoize (ashimema) <martin.renvoize>
Component:	Templates	Assignee:	Bugs List <koha-bugs>
Status:	NEW ---	QA Contact:	Testopia <testopia>
Severity:	enhancement
Priority:	P5 - low	CC:	dcook, jonathan.druart, kyle, nick, tomascohen
Version:	Main
Hardware:	All
OS:	All
See Also:	https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=29859 https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=23991
Change sponsored?:	---	Patch complexity:	---
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Description Martin Renvoize (ashimema) 2022-02-03 15:05:13 UTC

I noticed a pattern recently whereby we often call a count prior to iterating over the resultset:

[% IF things.count %]
<table>
  . . .
  [% FOREACH thing IN things %]
  <td>[% thing.whatever %]</td>
  [% END %]
</table>
[% END %]

This introduces a count(*) DB call. We could instead use the first iteration of the iterator to setup the boilerplate and reduce our DB hits.

[% FOREACH thing IN things %]
[% IF thing.first %]
<table>
[% END %]
  <td>[% thing.whatever %]</td>
[% IF thing.last %]
</table>
[% END %]
[% END %]

Comment 1 Martin Renvoize (ashimema) 2022-02-03 15:06:06 UTC

Doh.. it's wouldn'y be 'thing.first' and 'thing.last'.. it would be the special variables.. 'loop.first' and 'loop.last' in the above example.

Comment 2 David Cook 2022-02-07 02:57:44 UTC

Sounds reasonable to me

Comment 3 Jonathan Druart 2022-02-07 15:48:51 UTC

Sometimes we need to know if there is are least 1 row, to display a title for instance, or actions (check/uncheck all) at the top of the table.

We will then end up with 2 patterns. Not a big deal, but worst noting it.

Maybe better to have a TT var defined at the top of the template then reused all along?