allow count() with GROUP BY

diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm
index e696555..f3617e7 100644 (file)
--- a/lib/DBIx/Class/ResultSet.pm
+++ b/lib/DBIx/Class/ResultSet.pm
@@ -373,17 +373,37 @@ on the resultset and counts the results of that.
 sub count {
   my $self = shift;
   return $self->search(@_)->count if @_ && defined $_[0];
-  $self->throw_exception(
-    "Unable to ->count with a GROUP BY" 
-  ) if defined $self->{attrs}{group_by};
   unless (defined $self->{count}) {
+    my $group_by;
+    my $select = { 'count' => '*' };
+    if( $group_by = delete $self->{attrs}{group_by} ) {
+      my @distinct = @$group_by;
+      # todo: try CONCAT for multi-column pk
+      my @pk = $self->result_source->primary_columns;
+      if( scalar(@pk) == 1 ) {
+        my $pk = shift(@pk);
+        my $alias = $self->{attrs}{alias};
+        my $re = qr/^($alias\.)?$pk$/;
+        foreach my $column ( @$group_by ) {
+          if( $column =~ $re ) {
+            @distinct = ( $column );
+            last;
+          }
+        } 
+      }
+
+      $select = { count => { 'distinct' => \@distinct } };
+      #use Data::Dumper; die Dumper $select;
+    }
+
     my $attrs = { %{ $self->{attrs} },
-                  select => { 'count' => '*' },
+                  select => $select,
                   as => [ 'count' ] };
     # offset, order by and page are not needed to count. record_filter is cdbi
     delete $attrs->{$_} for qw/rows offset order_by page pager record_filter/;
         
     ($self->{count}) = (ref $self)->new($self->result_source, $attrs)->cursor->next;
+    $self->{attrs}{group_by} = $group_by;
   }
   return 0 unless $self->{count};
   my $count = $self->{count};

diff --git a/t/run/16joins.tl b/t/run/16joins.tl
index 1b3ff15..14ca4bd 100644 (file)
--- a/t/run/16joins.tl
+++ b/t/run/16joins.tl
@@ -7,7 +7,7 @@ BEGIN {
     eval "use DBD::SQLite";
     plan $@
         ? ( skip_all => 'needs DBD::SQLite for testing' )
-        : ( tests => 27 );
+        : ( tests => 31 );
 }
 
 # test the abstract join => SQL generator
@@ -188,6 +188,23 @@ my @artists = $schema->resultset("Artist")->search({ 'tags.tag' => 'Shiny' },
 
 cmp_ok( @artists, '==', 2, "two-join search ok" );
 
+$rs = $schema->resultset("CD")->search(
+  {},
+  { group_by => [qw/ title me.cdid /] }
+);
+
+cmp_ok( $rs->count, '==', 5, "count() ok after group_by on main pk" );
+
+cmp_ok( scalar $rs->all, '==', 5, "all() returns same count as count() after group_by on main pk" );
+
+$rs = $schema->resultset("CD")->search(
+  {},
+  { join => [qw/ artist /], group_by => [qw/ artist.name /] }
+);
+
+cmp_ok( $rs->count, '==', 3, "count() ok after group_by on related column" );
+
+cmp_ok( scalar $rs->all, '==', 3, "all() returns same count as count() after group_by on related column" );
 }
 
 1;