[Dbix-class] DBIx HAVING and COUNT error

[Stefan Hornburg (Racke)]

On 09/03/2016 03:38 AM, Rajeev Prasad wrote:
> DBIx error in webserver log:
> 
> [cgi:error] [pid 29640] ... AH01215: Can't locate object method "HAVING" via package "COUNT" (perhaps you forgot to load
> "COUNT"?)
> 
> 
> the query:
> 
> my $obj_rs = $schema->resultset('itemList')->serach(
>                 { t_id => { -in => [ $tStr ] }},
>                 {
>                     group_by => [ qw(i_id) ],
>                     HAVING COUNT('t_id') = $tCount
>                 }
>             );
> 
> 
> currently database has no records which match the query. but i was not expecting such an error.
> 
> what is wrong in my statement?

You can't just drop in literal SQL like that and expect it to work - because Perl now assumes
"HAVING COUNT" being Perl code. I suppose "use strict; use warnings" would have alerted you of
that.

It is possible to you use literal SQL with DBIx::Class, please refer to the docs.

I would suggest a different approach - using subqueries. Please take a look at the excellent
advent calendar post from fREW:

http://www.perladvent.org/2012/2012-12-21.html

This is still accurate.

I covered a few use cases in my presentation at the Alpine Perl Workshop:

https://www.linuxia.de/talks/alpine2016/dbic-pr-en-beamer.pdf

Regards
        Racke

> 
> thank you.
> Rajeev
> 
> 
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