From: Peter Rabbitson <ribasushi@cpan.org>
Date: Tue, 30 Jun 2009 14:23:06 +0000 (+0000)
Subject: rs->get_column now properly recognizes prefetch and collapses if at all possible
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=d8dbe471a2f98a0bc2de5e629f22ee2f2ec034ef;p=dbsrgits%2FDBIx-Class-Historic.git

rs->get_column now properly recognizes prefetch and collapses if at all possible
---

diff --git a/lib/DBIx/Class/ResultSetColumn.pm b/lib/DBIx/Class/ResultSetColumn.pm
index 037b771..1596e53 100644
--- a/lib/DBIx/Class/ResultSetColumn.pm
+++ b/lib/DBIx/Class/ResultSetColumn.pm
@@ -39,27 +39,48 @@ sub new {
 
   $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
+  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 $init_attrs = $new_parent_rs->{attrs} ||= {};
-  delete $init_attrs->{collapse};
-  $init_attrs->{join} = $rs->_merge_attr( delete $init_attrs->{join}, delete $init_attrs->{prefetch} );
+
+  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 $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;
 
+  # {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;
   return $new;
 }
diff --git a/t/88result_set_column.t b/t/88result_set_column.t
index 66169f3..aac98dc 100644
--- a/t/88result_set_column.t
+++ b/t/88result_set_column.t
@@ -8,10 +8,9 @@ use DBICTest;
 
 my $schema = DBICTest->init_schema();
 
-plan tests => 18;
+plan tests => 20;
 
-my $cd;
-my $rs = $cd = $schema->resultset("CD")->search({}, { order_by => 'cdid' });
+my $rs = $schema->resultset("CD")->search({}, { order_by => 'cdid' });
 
 my $rs_title = $rs->get_column('title');
 my $rs_year = $rs->get_column('year');
@@ -76,3 +75,22 @@ is ($schema->resultset('BooksInLibrary')->get_column ('price')->sum, 125, 'Sum o
 my $owner = $schema->resultset('Owners')->find ({ name => 'Newton' });
 ok ($owner->books->count > 1, 'Owner Newton has multiple books');
 is ($owner->search_related ('books')->get_column ('price')->sum, 60, 'Correctly calculated price of all owned books');
+
+
+# make sure joined/prefetched get_column of a PK dtrt
+
+$rs->reset;
+my $j_rs = $rs->search ({}, { join => 'tracks' })->get_column ('cdid');
+is_deeply (
+  [ $j_rs->all ],
+  [ map { my $c = $rs->next; ( ($c->id) x $c->tracks->count ) } (1 .. $rs->count) ],
+  'join properly explodes amount of rows from get_column',
+);
+
+$rs->reset;
+my $p_rs = $rs->search ({}, { prefetch => 'tracks' })->get_column ('cdid');
+is_deeply (
+  [ $p_rs->all ],
+  [ $rs->get_column ('cdid')->all ],
+  'prefetch properly collapses amount of rows from get_column',
+);
diff --git a/t/prefetch/grouped.t b/t/prefetch/grouped.t
index 85fd730..3db5f9e 100644
--- a/t/prefetch/grouped.t
+++ b/t/prefetch/grouped.t
@@ -77,7 +77,7 @@ for ($cd_rs->all) {
           SELECT me.cd
             FROM track me
             JOIN cd cd ON cd.cdid = me.cd
-          WHERE ( me.cd IN ( ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ? ) )
+          WHERE ( me.cd IN ( ?, ?, ?, ?, ? ) )
           GROUP BY me.cd
         )
       count_subq
@@ -94,11 +94,11 @@ for ($cd_rs->all) {
           SELECT me.cd, COUNT (me.trackid) AS track_count,
             FROM track me
             JOIN cd cd ON cd.cdid = me.cd
-          WHERE ( me.cd IN ( ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ? ) )
+          WHERE ( me.cd IN ( ?, ?, ?, ?, ? ) )
           GROUP BY me.cd
           ) as me
         JOIN cd cd ON cd.cdid = me.cd
-      WHERE ( me.cd IN ( ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ? ) )
+      WHERE ( me.cd IN ( ?, ?, ?, ?, ? ) )
     )',
     [ map { [ 'me.cd' => $_] } ( ($cd_rs->get_column ('cdid')->all) x 2 ) ],
     'next() query generated expected SQL',