X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FResultSetColumn.pm;h=4f48d330384563446542c305f61592a77ac15e93;hb=d4daee7b54e38e4b3d3d0a77759bddc1a4ede6e5;hp=f27259297dc2ac0f3507cfe763332738493b9fdd;hpb=658fa250be6ed1944d042ccf985d5c05d41111f6;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/ResultSetColumn.pm b/lib/DBIx/Class/ResultSetColumn.pm
index f272592..4f48d33 100644
--- a/lib/DBIx/Class/ResultSetColumn.pm
+++ b/lib/DBIx/Class/ResultSetColumn.pm
@@ -36,39 +36,74 @@ 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 $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
+
+  $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 = $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;
 
+  # {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}}) {
+
+    # 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 ];
+        last;
+      }
+    }
+  }
+
   my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class;
-  $new->throw_exception("column must be supplied") unless $column;
   return $new;
 }
 
-=head2 as_query
+=head2 as_query (EXPERIMENTAL)
 
 =over 4
 
 =item Arguments: none
 
-=item Return Value: [ $sql, @bind ]
+=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.
+
+B<NOTE>: This feature is still experimental.
+
 =cut
 
-sub as_query { return shift->_resultset->as_query }
+sub as_query { return shift->_resultset->as_query(@_) }
 
 =head2 next
 
@@ -184,6 +219,24 @@ sub 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
@@ -205,6 +258,24 @@ sub max {
   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
@@ -226,6 +297,24 @@ sub sum {
   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
@@ -248,8 +337,8 @@ value. Produces the following SQL:
 
 sub func {
   my ($self,$function) = @_;
-  my $cursor = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_select}}, as => [$self->{_as}]})->cursor;
-  
+  my $cursor = $self->func_rs($function)->cursor;
+
   if( wantarray ) {
     return map { $_->[ 0 ] } $cursor->all;
   }
@@ -257,12 +346,36 @@ sub func {
   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}) {