* Added ->first and ->reset implementation to ResultSetColumn.

[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / ResultSetColumn.pm

diff --git a/lib/DBIx/Class/ResultSetColumn.pm b/lib/DBIx/Class/ResultSetColumn.pm
index 49b8456..3585d17 100644 (file)
--- a/lib/DBIx/Class/ResultSetColumn.pm
+++ b/lib/DBIx/Class/ResultSetColumn.pm
@@ -2,6 +2,7 @@ package DBIx::Class::ResultSetColumn;
 use strict;
 use warnings;
 use base 'DBIx::Class';
+use List::Util;
 
 =head1 NAME
 
@@ -35,12 +36,15 @@ passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>.
 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;
+  $new_parent_rs->{attrs}->{$_} = undef for qw(prefetch include_columns +select +as); # prefetch, include_columns, +select, +as cause additional columns to be fetched
+  my ($select, $as) =
+    map { defined $_ ? ($attrs->{select}->[$_], $attrs->{as}->[$_]) : ($column, $column) }
+      List::Util::first { ($attrs->{as} || [])->[$_] eq $column }
+        0..$#{$attrs->{as} || []};
+  my $new = bless { _select => $select, _as => $as, _parent_resultset => $new_parent_rs }, $class;
+  $new->throw_exception("column must be supplied") unless $column;
   return $new;
 }
 
@@ -64,9 +68,7 @@ one value.
 
 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;
 }
 
@@ -90,7 +92,53 @@ than row objects.
 
 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
@@ -111,8 +159,7 @@ resultset (or C<undef> if there are none).
 =cut
 
 sub min {
-  my $self = shift;
-  return $self->func('MIN');
+  return shift->func('MIN');
 }
 
 =head2 max
@@ -133,8 +180,7 @@ resultset (or C<undef> if there are none).
 =cut
 
 sub max {
-  my $self = shift;
-  return $self->func('MAX');
+  return shift->func('MAX');
 }
 
 =head2 sum
@@ -155,8 +201,7 @@ 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 func
@@ -180,13 +225,60 @@ value. Produces the following SQL:
 =cut
 
 sub func {
+  my ($self,$function) = @_;
+  my $cursor = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_select}}, as => [$self->{_as}]})->cursor;
+  
+  if( wantarray ) {
+    return map { $_->[ 0 ] } $cursor->all;
+  }
+
+  return ( $cursor->next )[ 0 ];
+}
+
+=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(@_);
+  }
+}
+
+=head2 _resultset
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $resultset
+
+=back
+
+  $year_col->_resultset->next
+
+Returns the underlying resultset. Creates it from the parent resultset if
+necessary.
+
+=cut
+
+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;
 
 =head1 AUTHORS