Changes and small ommission

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

diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm
index 5d96065..173857c 100644 (file)
--- a/lib/DBIx/Class/ResultSet.pm
+++ b/lib/DBIx/Class/ResultSet.pm
@@ -291,18 +291,19 @@ sub search_rs {
     $rows = $self->get_cache;
   }
 
+  # reset the selector list
+  if (List::Util::first { exists $attrs->{$_} } qw{columns select as}) {
+     delete @{$our_attrs}{qw{select as columns +select +as +columns include_columns}};
+  }
+
   my $new_attrs = { %{$our_attrs}, %{$attrs} };
 
   # merge new attrs into inherited
-  foreach my $key (qw/join prefetch +select +as bind/) {
+  foreach my $key (qw/join prefetch +select +as +columns include_columns bind/) {
     next unless exists $attrs->{$key};
     $new_attrs->{$key} = $self->_merge_attr($our_attrs->{$key}, $attrs->{$key});
   }
 
-  if (List::Util::first { exists $new_attrs->{$_} } qw{select as columns}) {
-     delete $new_attrs->{$_} for (qw{+select +as +columns});
-  }
-
   my $cond = (@_
     ? (
         (@_ == 1 || ref $_[0] eq "HASH")
@@ -2592,6 +2593,68 @@ sub current_source_alias {
   return ($self->{attrs} || {})->{alias} || 'me';
 }
 
+=head2 as_subselect_rs
+
+=over 4
+
+=item Arguments: none
+
+=item Return Value: $resultset
+
+=back
+
+Act as a barrier to SQL symbols.  The resultset provided will be made into a
+"virtual view" by including it as a subquery within the from clause.  From this
+point on, any joined tables are inaccessible to ->search on the resultset (as if
+it were simply where-filtered without joins).  For example:
+
+ my $rs = $schema->resultset('Bar')->search({'x.name' => 'abc'},{ join => 'x' });
+
+ # 'x' now pollutes the query namespace
+
+ # So the following works as expected
+ my $ok_rs = $rs->search({'x.other' => 1});
+
+ # But this doesn't: instead of finding a 'Bar' related to two x rows (abc and
+ # def) we look for one row with contradictory terms and join in another table
+ # (aliased 'x_2') which we never use
+ my $broken_rs = $rs->search({'x.name' => 'def'});
+
+ my $rs2 = $rs->as_subselect_rs;
+
+ # doesn't work - 'x' is no longer accessible in $rs2, having been sealed away
+ my $not_joined_rs = $rs2->search({'x.other' => 1});
+
+ # works as expected: finds a 'table' row related to two x rows (abc and def)
+ my $correctly_joined_rs = $rs2->search({'x.name' => 'def'});
+
+Another example of when one might use this would be to select a subset of
+columns in a group by clause:
+
+ my $rs = $schema->resultset('Bar')->search(undef, {
+   group_by => [qw{ id foo_id baz_id }],
+ })->as_subselect_rs->search(undef, {
+   columns => [qw{ id foo_id }]
+ });
+
+In the above example normally columns would have to be equal to the group by,
+but because we isolated the group by into a subselect the above works.
+
+=cut
+
+sub as_subselect_rs {
+   my $self = shift;
+
+   return $self->result_source->resultset->search( undef, {
+      alias => $self->current_source_alias,
+      from => [{
+            $self->current_source_alias => $self->as_query,
+            -alias         => $self->current_source_alias,
+            -source_handle => $self->result_source->handle,
+         }]
+   });
+}
+
 # This code is called by search_related, and makes sure there
 # is clear separation between the joins before, during, and
 # after the relationship. This information is needed later