package DBIx::Class::ResultSetColumn;
+
use strict;
use warnings;
+
use base 'DBIx::Class';
+use Carp::Clan qw/^DBIx::Class/;
+use DBIx::Class::Exception;
+use List::Util ();
+
=head1 NAME
DBIx::Class::ResultSetColumn - helpful methods for messing
sub new {
my ($class, $rs, $column) = @_;
$class = ref $class if ref $class;
- my $new_parent_rs = $rs->search_rs; # we don't want to mess up the original, so clone it
- $new_parent_rs->{attrs}->{prefetch} = undef; # prefetch causes additional columns to be fetched
- my $new = bless { _column => $column, _parent_resultset => $new_parent_rs }, $class;
- $new->throw_exception("column must be supplied") unless $column;
+
+ $rs->throw_exception('column must be supplied') unless $column;
+
+ my $orig_attrs = $rs->_resolved_attrs;
+ 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 $new_attrs->{prefetch} );
+
+ # {collapse} would mean a has_many join was injected, which in turn means
+ # we need to group *IF WE CAN* (only if the column in question is unique)
+ if (!$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
+ my $constraints = { $rs->result_source->unique_constraints };
+ for my $constraint_columns ( values %$constraints ) {
+
+ next unless @$constraint_columns == 1;
+
+ my $col = $constraint_columns->[0];
+ my $fqcol = join ('.', $new_attrs->{alias}, $col);
+
+ if ($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
+
+=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.
+
+=cut
+
+sub as_query { return shift->_resultset->as_query(@_) }
+
=head2 next
=over 4
sub next {
my $self = shift;
- $self->{_resultset} = $self->{_parent_resultset}->search(undef, {select => [$self->{_column}], as => [$self->{_column}]}) unless ($self->{_resultset});
- my ($row) = $self->{_resultset}->cursor->next;
+
+ # using cursor so we don't inflate anything
+ my ($row) = $self->_resultset->cursor->next;
+
return $row;
}
sub all {
my $self = shift;
- return map {$_->[0]} $self->{_parent_resultset}->search(undef, {select => [$self->{_column}], as => [$self->{_column}]})->cursor->all;
+
+ # using cursor so we don't inflate anything
+ 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;
+
+ # using cursor so we don't inflate anything
+ $self->_resultset->cursor->reset;
+ my ($row) = $self->_resultset->cursor->next;
+
+ 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
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
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
return shift->func('SUM');
}
+=head2 sum_rs
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $resultset
+
+=back
+
+ my $rs = $year_col->sum_rs();
+
+Wrapper for ->func_rs for function SUM().
+
+=cut
+
+sub sum_rs { return shift->func_rs('SUM') }
+
=head2 func
=over 4
sub func {
my ($self,$function) = @_;
- my ($row) = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_column}}, as => [$self->{_column}]})->cursor->next;
- return $row;
+ 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 {
+ DBIx::Class::Exception->throw(@_);
+ }
+}
+
+# _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;
+
+ return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef,
+ {
+ select => [$self->{_select}],
+ as => [$self->{_as}]
+ }
+ );
}
1;
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