Alias the sum of two columns in a DBIx::Class resultset - perl

Question

SELECT me.id, me.date_created, me.date_updated, me.yes,
me.name, me.description, me.currency, me.locked, me.skip,
me.uri_part, me.user_id,
yes + currency as weight
FROM ideas me having ((weight < 5)) order by weight;
How can I generate that query in DBIx::Class without using literal SQL like this:
my $query = $rs->search({},
{
'+select' => \[
'yes + currency as weight',
],
rows => 1,
order_by => { -desc => [qw/weight name/] },
having => {
weight => { '<' => $self->yes + $self->currency },
},
});
use Data::Dumper;
warn Dumper($query->as_query);
I tried using -as, however, it seems to only be useful for working with columns generated from functions, as this:
'+select' => {
'yes + currency', '-as' => 'weight'
}
generates an error
"Odd number of elements in anonymous hash at
/data/TGC/lib/TGC/DB/Result/Idea.pm line 105, line 1000.
DBIx::Class::SQLMaker::_recurse_fields(): Malformed select argument -
too many keys in hash: SCALAR(0xbf14c40),weight"

Answer 1

Probably the most idiomatic thing I can think of in SQL Abstract expression, without straining too hard:
#!/usr/bin/env perl
use Modern::Perl;
use MySchema;
use Data::Dumper;
my $schema = MySchema->connect('dbi:SQLite:example.db');
my $rs = $schema->resultset('Sample')->search(
{
weight => { '<' => 5 },
},
{
'+select' => [
{ '' => \'`me`.`yes` + `me`.`currency`', -as => 'weight' }
]
}
);
say Dumper( $rs->as_query() );
Which is a contrived wrapping of the column names, but it does the job, sort of. Just don't know of any way to abstract the + here. But stil:
'(SELECT me.name, me.yes, me.currency, ( me.yes + me.currency ) AS weight FROM sample me WHERE ( weight < ? ))',
Unless you are just going for idiomatic perl, in which case:
{ '' => \(join " + ", qw/`me`.`yes` `me`.`currency`/), -as => 'weight' }
But either way seems a little contrived considering both forms are longer than the literal string.
Also note that weight is referenced in WHERE and not HAVING which is because that will blow up on various SQL engines.

Answer 2

The '+as' should be at the same level as '+select'
$idea = $rs->search({-and => [
name => { '<' => $self->name },
]},
{
'+select' => [
'yes + currency'
],
'+as' => [qw/weight/],
rows => 1,
order_by => ['weight', 'name'],
having => {
weight => { '<' => $self->yes + $self->currency },
},
})->single;