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 # If $column can be found in the 'as' list of the parent resultset, use the
44 # corresponding element of its 'select' list (to keep any custom column
45 # definition set up with 'select' or '+select' attrs), otherwise use $column
46 # (to create a new column definition on-the-fly).
47 my $as_list = $attrs->{as} || [];
48 my $select_list = $attrs->{select} || [];
49 my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list;
50 my $select = defined $as_index ? $select_list->[$as_index] : $column;
52 my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class;
53 $new->throw_exception("column must be supplied") unless $column;
63 =item Return Value: \[ $sql, @bind ]
67 Returns the SQL query and bind vars associated with the invocant.
71 sub as_query { return shift->_resultset->as_query }
79 =item Return Value: \[ $sql, @bind ]
83 Returns the SQL query and bind vars associated with the invocant.
85 The SQL will be wrapped in parentheses, ready for use as a subselect.
91 my $arr = ${$self->as_query(@_)};
92 $arr->[0] = '( ' . $arr->[0] . ' )';
100 =item Arguments: none
102 =item Return Value: $sql
106 Returns the SQL query associated with the invocant. All bind vars
107 will have been bound using C<< DBI->quote() >>.
113 my $arr = ${$self->as_query(@_)};
114 my $sql = shift @$arr;
115 my $dbh = $self->_resultset->result_source->schema->storage->dbh;
116 $sql =~ s/\?/$dbh->quote((shift @$arr)->[1])/eg;
124 =item Arguments: none
126 =item Return Value: $value
130 Returns the next value of the column in the resultset (or C<undef> if
133 Much like L<DBIx::Class::ResultSet/next> but just returning the
140 my ($row) = $self->_resultset->cursor->next;
148 =item Arguments: none
150 =item Return Value: @values
154 Returns all values of the column in the resultset (or C<undef> if
157 Much like L<DBIx::Class::ResultSet/all> but returns values rather
164 return map { $_->[0] } $self->_resultset->cursor->all;
171 =item Arguments: none
173 =item Return Value: $self
177 Resets the underlying resultset's cursor, so you can iterate through the
178 elements of the column again.
180 Much like L<DBIx::Class::ResultSet/reset>.
186 $self->_resultset->cursor->reset;
194 =item Arguments: none
196 =item Return Value: $value
200 Resets the underlying resultset and returns the next value of the column in the
201 resultset (or C<undef> if there is none).
203 Much like L<DBIx::Class::ResultSet/first> but just returning the one value.
209 my ($row) = $self->_resultset->cursor->reset->next;
217 =item Arguments: none
219 =item Return Value: $lowest_value
223 my $first_year = $year_col->min();
225 Wrapper for ->func. Returns the lowest value of the column in the
226 resultset (or C<undef> if there are none).
231 return shift->func('MIN');
238 =item Arguments: none
240 =item Return Value: $highest_value
244 my $last_year = $year_col->max();
246 Wrapper for ->func. Returns the highest value of the column in the
247 resultset (or C<undef> if there are none).
252 return shift->func('MAX');
259 =item Arguments: none
261 =item Return Value: $sum_of_values
265 my $total = $prices_col->sum();
267 Wrapper for ->func. Returns the sum of all the values in the column of
268 the resultset. Use on varchar-like columns at your own risk.
273 return shift->func('SUM');
280 =item Arguments: $function
282 =item Return Value: $function_return_value
286 $rs = $schema->resultset("CD")->search({});
287 $length = $rs->get_column('title')->func('LENGTH');
289 Runs a query using the function on the column and returns the
290 value. Produces the following SQL:
292 SELECT LENGTH( title ) FROM cd me
297 my ($self,$function) = @_;
298 my $cursor = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_select}}, as => [$self->{_as}]})->cursor;
301 return map { $_->[ 0 ] } $cursor->all;
304 return ( $cursor->next )[ 0 ];
307 =head2 throw_exception
309 See L<DBIx::Class::Schema/throw_exception> for details.
313 sub throw_exception {
315 if (ref $self && $self->{_parent_resultset}) {
316 $self->{_parent_resultset}->throw_exception(@_)
326 # Return Value: $resultset
328 # $year_col->_resultset->next
330 # Returns the underlying resultset. Creates it from the parent resultset if
336 return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef,
338 select => [$self->{_select}],
348 Luke Saunders <luke.saunders@gmail.com>
354 You may distribute this code under the same terms as Perl itself.