X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FResultSetColumn.pm;h=e11f86849ab9365ce98cabfb788eeed4ed6beb15;hb=7e3dc46f39301189250953880d568cebdc914a77;hp=1596e53b84720f8ec24952f0e38da83297dcd2df;hpb=d8dbe471a2f98a0bc2de5e629f22ee2f2ec034ef;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/ResultSetColumn.pm b/lib/DBIx/Class/ResultSetColumn.pm
index 1596e53..e11f868 100644
--- a/lib/DBIx/Class/ResultSetColumn.pm
+++ b/lib/DBIx/Class/ResultSetColumn.pm
@@ -1,7 +1,12 @@
 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
@@ -37,31 +42,55 @@ sub new {
   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} );
 
   # 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 { $_ => 1 } ($rs->result_source->columns, $column);
+  if (
+    scalar grep
+      { ! $collist{$_} }
+      ( $rs->result_source->schema->storage->_parse_order_by ($orig_attrs->{order_by} ) ) 
+  ) {
+    my $alias = $rs->current_source_alias;
+    # nuke the prefetch before collapsing to sql
+    my $subq_rs = $rs->search;
+    $subq_rs->{attrs}{join} = $subq_rs->_merge_attr( $subq_rs->{attrs}{join}, delete $subq_rs->{attrs}{prefetch} );
+
+    $new_parent_rs = $rs->result_source->resultset->search ( {}, {
+      alias => $alias,
+      from => [{
+        $alias => $subq_rs->as_query,
+        -alias => $alias,
+        -source_handle => $rs->result_source->handle,
+      }]
+    });
+  }
+
+  $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_attr( $new_attrs->{join}, delete $new_attrs->{prefetch} );
+
   # {collapse} would mean a has_many join was injected, which in turn means
-  # we need to group IF WE CAN (only if the column in question is unique)
+  # we need to group *IF WE CAN* (only if the column in question is unique)
   if (!$new_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) {
 
     # scan for a constraint that would contain our column only - that'd be proof
@@ -76,16 +105,24 @@ sub new {
 
       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
 
@@ -99,8 +136,6 @@ Returns the SQL query and bind vars associated with the invocant.
 
 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(@_) }
@@ -125,7 +160,10 @@ one value.
 
 sub next {
   my $self = shift;
+
+  # using cursor so we don't inflate anything
   my ($row) = $self->_resultset->cursor->next;
+
   return $row;
 }
 
@@ -149,6 +187,8 @@ than row objects.
 
 sub all {
   my $self = shift;
+
+  # using cursor so we don't inflate anything
   return map { $_->[0] } $self->_resultset->cursor->all;
 }
 
@@ -194,7 +234,38 @@ Much like L<DBIx::Class::ResultSet/first> but just returning the one value.
 
 sub first {
   my $self = shift;
-  my ($row) = $self->_resultset->cursor->reset->next;
+
+  # 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;
 }
 
@@ -338,7 +409,7 @@ value. Produces the following SQL:
 sub func {
   my ($self,$function) = @_;
   my $cursor = $self->func_rs($function)->cursor;
-  
+
   if( wantarray ) {
     return map { $_->[ 0 ] } $cursor->all;
   }
@@ -373,15 +444,17 @@ sub func_rs {
 =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(@_);
+    $self->{_parent_resultset}->throw_exception(@_);
+  }
+  else {
+    DBIx::Class::Exception->throw(@_);
   }
 }
 
@@ -395,7 +468,7 @@ sub throw_exception {
 #
 # Returns the underlying resultset. Creates it from the parent resultset if
 # necessary.
-# 
+#
 sub _resultset {
   my $self = shift;