use strict;
use warnings;
use base 'DBIx::Class';
+use List::Util;
=head1 NAME
=head1 DESCRIPTION
-A convenience class used to perform operations on a specific column of a resultset.
+A convenience class used to perform operations on a specific column of
+a resultset.
=cut
my $obj = DBIx::Class::ResultSetColumn->new($rs, $column);
-Creates a new resultset column object from the resultset and column passed as params
+Creates a new resultset column object from the resultset and column
+passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>.
=cut
sub new {
my ($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);
+ my $new_parent_rs = $rs->search_rs; # we don't want to mess up the original, so clone it
+ my $attrs = $new_parent_rs->_resolved_attrs;
+ $new_parent_rs->{attrs}->{prefetch} = undef; # prefetch cause additional columns to be fetched
+
+ # If $column can be found in the 'as' list of the parent resultset, use the
+ # corresponding element of its 'select' list (to keep any custom column
+ # definition set up with 'select' or '+select' attrs), otherwise use $column
+ # (to create a new column definition on-the-fly).
+ my $as_list = $attrs->{as} || [];
+ my $select_list = $attrs->{select} || [];
+ my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list;
+ my $select = defined $as_index ? $select_list->[$as_index] : $column;
+
+ my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class;
+ $new->throw_exception("column must be supplied") unless $column;
return $new;
}
+=head2 as_query (EXPERIMENTAL)
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: \[ $sql, @bind ]
+
+=back
+
+Returns the SQL query and bind vars associated with the invocant.
+
+This is generally used as the RHS for a subquery.
+
+B<NOTE>: This feature is still experimental.
+
+=cut
+
+sub as_query { return shift->_resultset->as_query }
+
=head2 next
=over 4
=back
-Returns the next value of the column in the resultset (C<undef> is there is none).
+Returns the next value of the column in the resultset (or C<undef> if
+there is none).
-Much like $rs->next but just returning the one value
+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) = $self->{_resultset}->cursor->next;
+ my ($row) = $self->_resultset->cursor->next;
return $row;
}
=back
-Returns all values of the column in the resultset (C<undef> is there are none).
+Returns all values of the column in the resultset (or C<undef> if
+there are none).
-Much like $rs->all but returns values rather than row objects
+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;
+ return map { $_->[0] } $self->_resultset->cursor->all;
+}
+
+=head2 reset
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $self
+
+=back
+
+Resets the underlying resultset's cursor, so you can iterate through the
+elements of the column again.
+
+Much like L<DBIx::Class::ResultSet/reset>.
+
+=cut
+
+sub reset {
+ my $self = shift;
+ $self->_resultset->cursor->reset;
+ return $self;
+}
+
+=head2 first
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $value
+
+=back
+
+Resets the underlying resultset and returns the next value of the column in the
+resultset (or C<undef> if there is none).
+
+Much like L<DBIx::Class::ResultSet/first> but just returning the one value.
+
+=cut
+
+sub first {
+ my $self = shift;
+ my ($row) = $self->_resultset->cursor->reset->next;
+ return $row;
}
=head2 min
=back
-Wrapper for ->func. Returns the lowest value of the column in the resultset (C<undef> is there are none).
+ 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');
+ return shift->func('MIN');
}
+=head2 min_rs
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $resultset
+
+=back
+
+ my $rs = $year_col->min_rs();
+
+Wrapper for ->func_rs for function MIN().
+
+=cut
+
+sub min_rs { return shift->func_rs('MIN') }
+
=head2 max
=over 4
=back
-Wrapper for ->func. Returns the highest value of the column in the resultset (C<undef> is there are none).
+ 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');
+ return shift->func('MAX');
}
+=head2 max_rs
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $resultset
+
+=back
+
+ my $rs = $year_col->max_rs();
+
+Wrapper for ->func_rs for function MAX().
+
+=cut
+
+sub max_rs { return shift->func_rs('MAX') }
+
=head2 sum
=over 4
=back
-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.
+ 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');
+ return shift->func('SUM');
}
+=head2 sum_rs
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $resultset
+
+=back
+
+ my $rs = $year_col->sum_rs();
+
+Wrapper for ->func_rs for function SUM().
+
+=cut
+
+sub sum_rs { return shift->func_rs('SUM') }
+
=head2 func
=over 4
=back
-Runs a query using the function on the column and returns the value. For example
- $rs $schema->resultset("CD")->search({});
- $rs->get_column('title')->func('LENGTH');
+ $rs = $schema->resultset("CD")->search({});
+ $length = $rs->get_column('title')->func('LENGTH');
-Produces the following SQL
- SELECT LENGTH( title ) from cd me
+Runs a query using the function on the column and returns the
+value. Produces the following SQL:
+
+ SELECT LENGTH( title ) FROM cd me
=cut
sub func {
+ my ($self,$function) = @_;
+ my $cursor = $self->func_rs($function)->cursor;
+
+ if( wantarray ) {
+ return map { $_->[ 0 ] } $cursor->all;
+ }
+
+ return ( $cursor->next )[ 0 ];
+}
+
+=head2 func_rs
+
+=over 4
+
+=item Arguments: $function
+
+=item Return Value: $resultset
+
+=back
+
+Creates the resultset that C<func()> uses to run its query.
+
+=cut
+
+sub func_rs {
+ my ($self,$function) = @_;
+ return $self->{_parent_resultset}->search(
+ undef, {
+ select => {$function => $self->{_select}},
+ as => [$self->{_as}],
+ },
+ );
+}
+
+=head2 throw_exception
+
+See L<DBIx::Class::Schema/throw_exception> for details.
+
+=cut
+
+sub throw_exception {
+ my $self=shift;
+ if (ref $self && $self->{_parent_resultset}) {
+ $self->{_parent_resultset}->throw_exception(@_)
+ } else {
+ croak(@_);
+ }
+}
+
+# _resultset
+#
+# Arguments: none
+#
+# Return Value: $resultset
+#
+# $year_col->_resultset->next
+#
+# Returns the underlying resultset. Creates it from the parent resultset if
+# necessary.
+#
+sub _resultset {
my $self = shift;
- my $function = shift;
- my ($row) = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_column}}, as => [$self->{_column}]})->cursor->next;
- return $row;
+ return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef,
+ {
+ select => [$self->{_select}],
+ as => [$self->{_as}]
+ }
+ );
}
1;
Luke Saunders <luke.saunders@gmail.com>
+Jess Robinson
+
=head1 LICENSE
You may distribute this code under the same terms as Perl itself.
projects / dbsrgits/DBIx-Class.git / blobdiff