X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FResultSetColumn.pm;h=a459bc3002aca62d38add86c91e4618fac13abfa;hb=94244987e66865e4c0c37385248176330ae69029;hp=3ed93426237ab04cbb26ca36c97c447f550575de;hpb=7ae9706c9d89bf85830a5598f30d48b8fb2a3199;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/ResultSetColumn.pm b/lib/DBIx/Class/ResultSetColumn.pm
index 3ed9342..a459bc3 100644
--- a/lib/DBIx/Class/ResultSetColumn.pm
+++ b/lib/DBIx/Class/ResultSetColumn.pm
@@ -1,8 +1,15 @@
 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;
+
+# not importing first() as it will clash with our own method
+use List::Util ();
 
 =head1 NAME
 
@@ -37,35 +44,82 @@ 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 $new_parent_rs = $rs->search_rs; # we don't want to mess up the original, so clone it
-
-  # 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
-  for my $attr (qw/prefetch collapse/) {
-    for (qw/attrs _attrs/) {
-      delete $new_parent_rs->{$_}{$attr} if ref $new_parent_rs->{$_};
-    }
-  }
+  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 $attrs = $new_parent_rs->_resolved_attrs;
-
-  my $as_list = $attrs->{as} || [];
-  my $select_list = $attrs->{select} || [];
+  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 (EXPERIMENTAL)
+=head2 as_query
 
 =over 4
 
@@ -79,8 +133,6 @@ 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(@_) }
@@ -105,7 +157,10 @@ one value.
 
 sub next {
   my $self = shift;
+
+  # using cursor so we don't inflate anything
   my ($row) = $self->_resultset->cursor->next;
+
   return $row;
 }
 
@@ -129,6 +184,8 @@ than row objects.
 
 sub all {
   my $self = shift;
+
+  # using cursor so we don't inflate anything
   return map { $_->[0] } $self->_resultset->cursor->all;
 }
 
@@ -174,7 +231,38 @@ 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;
 }
 
@@ -318,7 +406,7 @@ value. Produces the following SQL:
 sub func {
   my ($self,$function) = @_;
   my $cursor = $self->func_rs($function)->cursor;
-  
+
   if( wantarray ) {
     return map { $_->[ 0 ] } $cursor->all;
   }
@@ -353,15 +441,17 @@ 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(@_);
   }
 }
 
@@ -375,7 +465,7 @@ sub throw_exception {
 #
 # Returns the underlying resultset. Creates it from the parent resultset if
 # necessary.
-# 
+#
 sub _resultset {
   my $self = shift;