package DBIx::Class::ResultSetColumn;
+
use strict;
use warnings;
+
use base 'DBIx::Class';
-use List::Util;
+
+use Carp::Clan qw/^DBIx::Class/;
+use DBIx::Class::Exception;
+use List::Util ();
=head1 NAME
my ($class, $rs, $column) = @_;
$class = ref $class if ref $class;
- $rs->throw_exception("column must be supplied") unless $column;
+ $rs->throw_exception('column must be supplied') unless $column;
my $orig_attrs = $rs->_resolved_attrs;
- my $new_parent_rs = $rs->search_rs;
-
- # prefetch causes additional columns to be fetched, but we can not just make a new
- # rs via the _resolved_attrs trick - we need to retain the separation between
- # +select/+as and select/as. At the same time we want to preserve any joins that the
- # prefetch would otherwise generate.
-
- my $new_attrs = $new_parent_rs->{attrs} ||= {};
- $new_attrs->{join} = $rs->_merge_attr( delete $new_attrs->{join}, delete $new_attrs->{prefetch} );
+ my $alias = $rs->current_source_alias;
# 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 = $orig_attrs->{as} || [];
my $select_list = $orig_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_parent_rs;
+ # analyze the order_by, and see if it is done over a function/nonexistentcolumn
+ # if this is the case we will need to wrap a subquery since the result of RSC
+ # *must* be a single column select
+ my %collist = map
+ { $_ => 1, ($_ =~ /\./) ? () : ( "$alias.$_" => 1 ) }
+ ($rs->result_source->columns, $column)
+ ;
+ if (
+ scalar grep
+ { ! $collist{$_} }
+ ( $rs->result_source->schema->storage->_extract_order_columns ($orig_attrs->{order_by} ) )
+ ) {
+ # nuke the prefetch before collapsing to sql
+ my $subq_rs = $rs->search;
+ $subq_rs->{attrs}{join} = $subq_rs->_merge_joinpref_attr( $subq_rs->{attrs}{join}, delete $subq_rs->{attrs}{prefetch} );
+ $new_parent_rs = $subq_rs->as_subselect_rs;
+ }
+
+ $new_parent_rs ||= $rs->search_rs;
+ my $new_attrs = $new_parent_rs->{attrs} ||= {};
+
+ # prefetch causes additional columns to be fetched, but we can not just make a new
+ # rs via the _resolved_attrs trick - we need to retain the separation between
+ # +select/+as and select/as. At the same time we want to preserve any joins that the
+ # prefetch would otherwise generate.
+ $new_attrs->{join} = $rs->_merge_joinpref_attr( $new_attrs->{join}, delete $new_attrs->{prefetch} );
+
# {collapse} would mean a has_many join was injected, which in turn means
- # we need to group IF WE CAN (only if the column in question is unique)
- if (!$new_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) {
+ # we need to group *IF WE CAN* (only if the column in question is unique)
+ if (!$orig_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) {
# scan for a constraint that would contain our column only - that'd be proof
# enough it is unique
if ($col eq $select or $fqcol eq $select) {
$new_attrs->{group_by} = [ $select ];
+ delete $new_attrs->{distinct}; # it is ignored when group_by is present
last;
}
}
+
+ if (!$new_attrs->{group_by}) {
+ carp (
+ "Attempting to retrieve non-unique column '$column' on a resultset containing "
+ . 'one-to-many joins will return duplicate results.'
+ );
+ }
}
my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class;
return $new;
}
-=head2 as_query (EXPERIMENTAL)
+=head2 as_query
=over 4
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(@_) }
return $row;
}
+=head2 single
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $value
+
+=back
+
+Much like L<DBIx::Class::ResultSet/single> fetches one and only one column
+value using the cursor directly. If additional rows are present a warning
+is issued before discarding the cursor.
+
+=cut
+
+sub single {
+ my $self = shift;
+
+ my $attrs = $self->_resultset->_resolved_attrs;
+ my ($row) = $self->_resultset->result_source->storage->select_single(
+ $attrs->{from}, $attrs->{select}, $attrs->{where}, $attrs
+ );
+
+ return $row;
+}
+
=head2 min
=over 4
sub throw_exception {
my $self=shift;
+
if (ref $self && $self->{_parent_resultset}) {
- $self->{_parent_resultset}->throw_exception(@_)
- } else {
- croak(@_);
+ $self->{_parent_resultset}->throw_exception(@_);
+ }
+ else {
+ DBIx::Class::Exception->throw(@_);
}
}
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