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|
package DBIx::Class::ResultSetColumn;
use strict;
use warnings;
use base 'DBIx::Class';
=head1 NAME
DBIx::Class::ResultSetColumn - helpful methods for messing
with a single column of the resultset
=head1 SYNOPSIS
$rs = $schema->resultset('CD')->search({ artist => 'Tool' });
$rs_column = $rs->get_column('year');
$max_year = $rs_column->max; #returns latest year
=head1 DESCRIPTION
A convenience class used to perform operations on a specific column of
a resultset.
=cut
=head1 METHODS
=head2 new
my $obj = DBIx::Class::ResultSetColumn->new($rs, $column);
Creates a new resultset column object from the resultset and column
passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>.
=cut
sub new {
my ($class, $rs, $column) = @_;
$class = ref $class if ref $class;
my $object_ref = { _column => $column,
_parent_resultset => $rs };
my $new = bless $object_ref, $class;
$new->throw_exception("column must be supplied") unless ($column);
return $new;
}
=head2 next
=over 4
=item Arguments: none
=item Return Value: $value
=back
Returns the next value of the column in the resultset (or C<undef> if
there is none).
Much like L<DBIx::Class::ResultSet/next> but just returning the
one value.
=cut
sub next {
my $self = shift;
$self->{_resultset} = $self->{_parent_resultset}->search(undef, {select => [$self->{_column}], as => [$self->{_column}]}) unless ($self->{_resultset});
my ($row) = $self->{_resultset}->cursor->next;
return $row;
}
=head2 all
=over 4
=item Arguments: none
=item Return Value: @values
=back
Returns all values of the column in the resultset (or C<undef> if
there are none).
Much like L<DBIx::Class::ResultSet/all> but returns values rather
than row objects.
=cut
sub all {
my $self = shift;
return map {$_->[0]} $self->{_parent_resultset}->search(undef, {select => [$self->{_column}], as => [$self->{_column}]})->cursor->all;
}
=head2 min
=over 4
=item Arguments: none
=item Return Value: $lowest_value
=back
my $first_year = $year_col->min();
Wrapper for ->func. Returns the lowest value of the column in the
resultset (or C<undef> if there are none).
=cut
sub min {
my $self = shift;
return $self->func('MIN');
}
=head2 max
=over 4
=item Arguments: none
=item Return Value: $highest_value
=back
my $last_year = $year_col->max();
Wrapper for ->func. Returns the highest value of the column in the
resultset (or C<undef> if there are none).
=cut
sub max {
my $self = shift;
return $self->func('MAX');
}
=head2 sum
=over 4
=item Arguments: none
=item Return Value: $sum_of_values
=back
my $total = $prices_col->sum();
Wrapper for ->func. Returns the sum of all the values in the column of
the resultset. Use on varchar-like columns at your own risk.
=cut
sub sum {
my $self = shift;
return $self->func('SUM');
}
=head2 func
=over 4
=item Arguments: $function
=item Return Value: $function_return_value
=back
$rs = $schema->resultset("CD")->search({});
$length = $rs->get_column('title')->func('LENGTH');
Runs a query using the function on the column and returns the
value. Produces the following SQL:
SELECT LENGTH( title ) FROM cd me
=cut
sub func {
my $self = shift;
my $function = shift;
my ($row) = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_column}}, as => [$self->{_column}]})->cursor->next;
return $row;
}
1;
=head1 AUTHORS
Luke Saunders <luke.saunders@gmail.com>
Jess Robinson
=head1 LICENSE
You may distribute this code under the same terms as Perl itself.
=cut
|
