1 package DBIx::Class::ResultSetColumn;
4 use base 'DBIx::Class';
9 DBIx::Class::ResultSetColumn - helpful methods for messing
10 with a single column of the resultset
14 $rs = $schema->resultset('CD')->search({ artist => 'Tool' });
15 $rs_column = $rs->get_column('year');
16 $max_year = $rs_column->max; #returns latest year
20 A convenience class used to perform operations on a specific column of
29 my $obj = DBIx::Class::ResultSetColumn->new($rs, $column);
31 Creates a new resultset column object from the resultset and column
32 passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>.
37 my ($class, $rs, $column) = @_;
38 $class = ref $class if ref $class;
39 my $new_parent_rs = $rs->search_rs; # we don't want to mess up the original, so clone it
40 my $attrs = $new_parent_rs->_resolved_attrs;
41 $new_parent_rs->{attrs}->{$_} = undef for qw(prefetch include_columns +select +as); # prefetch, include_columns, +select, +as cause additional columns to be fetched
43 map { defined $_ ? ($attrs->{select}->[$_], $attrs->{as}->[$_]) : ($column, $column) }
44 List::Util::first { ($attrs->{as} || [])->[$_] eq $column }
45 0..$#{$attrs->{as} || []};
46 my $new = bless { _select => $select, _as => $as, _parent_resultset => $new_parent_rs }, $class;
47 $new->throw_exception("column must be supplied") unless $column;
57 =item Return Value: $value
61 Returns the next value of the column in the resultset (or C<undef> if
64 Much like L<DBIx::Class::ResultSet/next> but just returning the
71 my ($row) = $self->_resultset->cursor->next;
81 =item Return Value: @values
85 Returns all values of the column in the resultset (or C<undef> if
88 Much like L<DBIx::Class::ResultSet/all> but returns values rather
95 return map { $_->[0] } $self->_resultset->cursor->all;
102 =item Arguments: none
104 =item Return Value: $self
108 Resets the underlying resultset's cursor, so you can iterate through the
109 elements of the column again.
111 Much like L<DBIx::Class::ResultSet/reset>.
117 $self->_resultset->cursor->reset;
125 =item Arguments: none
127 =item Return Value: $value
131 Resets the underlying resultset and returns the next value of the column in the
132 resultset (or C<undef> if there is none).
134 Much like L<DBIx::Class::ResultSet/first> but just returning the one value.
140 my ($row) = $self->_resultset->cursor->reset->next;
148 =item Arguments: none
150 =item Return Value: $lowest_value
154 my $first_year = $year_col->min();
156 Wrapper for ->func. Returns the lowest value of the column in the
157 resultset (or C<undef> if there are none).
162 return shift->func('MIN');
169 =item Arguments: none
171 =item Return Value: $highest_value
175 my $last_year = $year_col->max();
177 Wrapper for ->func. Returns the highest value of the column in the
178 resultset (or C<undef> if there are none).
183 return shift->func('MAX');
190 =item Arguments: none
192 =item Return Value: $sum_of_values
196 my $total = $prices_col->sum();
198 Wrapper for ->func. Returns the sum of all the values in the column of
199 the resultset. Use on varchar-like columns at your own risk.
204 return shift->func('SUM');
211 =item Arguments: $function
213 =item Return Value: $function_return_value
217 $rs = $schema->resultset("CD")->search({});
218 $length = $rs->get_column('title')->func('LENGTH');
220 Runs a query using the function on the column and returns the
221 value. Produces the following SQL:
223 SELECT LENGTH( title ) FROM cd me
228 my ($self,$function) = @_;
229 my $cursor = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_select}}, as => [$self->{_as}]})->cursor;
232 return map { $_->[ 0 ] } $cursor->all;
235 return ( $cursor->next )[ 0 ];
238 =head2 throw_exception
240 See L<DBIx::Class::Schema/throw_exception> for details.
244 sub throw_exception {
246 if (ref $self && $self->{_parent_resultset}) {
247 $self->{_parent_resultset}->throw_exception(@_)
257 =item Arguments: none
259 =item Return Value: $resultset
263 $year_col->_resultset->next
265 Returns the underlying resultset. Creates it from the parent resultset if
273 return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef,
275 select => [$self->{_select}],
286 Luke Saunders <luke.saunders@gmail.com>
292 You may distribute this code under the same terms as Perl itself.