[Dbix-class] Unknown column in 'group statement'

[Anthony Gladdish]

Hi Peter,

>-----Original Message-----
>From: Peter Rabbitson [mailto:rabbit+dbic at rabbit.us]
>Sent: 23 July 2009 22:45
>To: DBIx::Class user and developer list
>Subject: Re: [Dbix-class] Unknown column in 'group statement'
>
>On Thu, Jul 23, 2009 at 04:19:01PM +0100, Anthony Gladdish wrote:
>> Hi,
>>
>> Using:
>> Perl 5.10.
>> DBIC 0.08108.
>>
>> 1. My result source tables with relationships are:
>>
>> Event.pm:
>> __PACKAGE__->set_primary_key('id');
>> __PACKAGE__->belongs_to( 'leader' => 'Trainer' ) ;
>> __PACKAGE__->has_many( 'assistingtrainers' => 'AssistingTrainer', 'event' );
>> __PACKAGE__->many_to_many('assistants' => 'assistingtrainers', 'trainers' );
>>
>> AssistingTrainer.pm:
>> __PACKAGE__->set_primary_key('event','trainer');
>> __PACKAGE__->belongs_to( 'events' => 'Event', 'event' );
>> __PACKAGE__->belongs_to( 'trainers' => 'Trainer', 'trainer' );
>>
>> Trainer.pm:
>> __PACKAGE__->set_primary_key('id');
>>
>> 2. My ResultSet::Event.pm methods:
>>
>> sub goEvents {
>> 	my $self  = shift;
>> 	my $where = {};
>> 	$where->{status} = { '&' => 2 };
>> 	return $self->search($where);
>> }
>>
>> sub events_during_lookback_period {
>> 	my $self  = shift;
>> 	my $default_lookback_period = DateTime::Duration->new( years => 3 );
>> 	my $lookback_period = shift || $default_lookback_period;
>> 	my $earliest_date = DateTime->now() - $lookback_period;
>> 	return $self->goEvents()->search_rs(
>> 		{
>> 			-and => [
>> 				start => { '<', DateTime->now() },
>> 				start => { '>', $earliest_date },
>> 			],
>> 	    }
>> 	);
>> }
>>
>> sub distinct_assistants {
>> 	my $self  = shift;
>> 	my $assistants = [];
>> 	my $rs = $self->search_rs(
>> 		undef,
>> 		{
>> 			columns => [ qw/me.id/ ],
>>             		distinct => 1,
>>         		prefetch => [ { 'assistingtrainers' => 'trainers' } ],
>> 			join => [ { 'assistingtrainers' => 'trainers' } ],
>>         	},
>> 	);
>> 	while ( my $e = $rs->next() ) {
>> 		foreach my $at ( $e->assistingtrainers() ) {
>> 			push( @$assistants, $at->trainers );
>> 		}
>> 	}
>> 	return $assistants;
>> }
>>
>
>This is a design lapse - we married distinct with group_by too early
>in the code and what you are seeing is the fallout (i.e. distinct
>applies to all columns not just the ones you are trying to select).
>I will have to discuss this with the rest of the developers before
>we solve it, but for the time being simply change
>
>        distinct => 1
>
>to
>
>        group_by => [ qw/me.id/ ]
>
>The prefetch will keep working as expected.
>
>Cheers

This works, but only if I omit "columns =>" too, i.e.:

	{
 		group_by => [ qw/me.id/ ],
		prefetch => [ { 'assistingtrainers' => 'trainers' } ],
		join => [ { 'assistingtrainers' => 'trainers' } ],
	},

I'm assuming this is ok, although I would have thought "columns" and "group_by" would be needed together (correct me if I'm wrong), and doing this:

	{
 		columns => [ qw/me.id/ ],
		group_by => [ qw/me.id/ ],
		prefetch => [ { 'assistingtrainers' => 'trainers' } ],
		join => [ { 'assistingtrainers' => 'trainers' } ],
	},


... produces error:

DBIx::Class::ResultSet::next(): DBI Exception: DBD::mysql::st execute failed: Unknown column 'start' in 'where clause' [for Statement "SELECT me.id, assistingtrainers.event, assistingtrainers.trainer, trainers.id, trainers.name, trainers.email, trainers.phone, trainers.initials, trainers.loginId, trainers.password FROM (SELECT me.id FROM event me WHERE ( ( ( start < ? AND start > ? ) AND status & ? ) ) GROUP BY me.id) me LEFT JOIN trainer_assist assistingtrainers ON assistingtrainers.event = me.id LEFT JOIN trainer trainers ON trainers.id = assistingtrainers.trainer WHERE ( ( ( start < ? AND start > ? ) AND status & ? ) ) ORDER BY assistingtrainers.event" with ParamValues: 0='2009-07-24T09:46:14', 1='2006-07-24T09:46:14', 2=2, 3='2009-07-24T09:46:14', 4='2006-07-24T09:46:14', 5=2]

Thanks for your help,

Anthony