From: Peter Rabbitson <ribasushi@cpan.org>
Date: Sun, 28 Jun 2009 08:35:11 +0000 (+0000)
Subject: The proposed fix (do not add an extra join if it is already present in the topmost... 
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=096395af8e16de3f81ba55540e7379e82a192abf;p=dbsrgits%2FDBIx-Class-Historic.git

The proposed fix (do not add an extra join if it is already present in the topmost join)
---

diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm
index b012e03..1524efe 100644
--- a/lib/DBIx/Class/ResultSet.pm
+++ b/lib/DBIx/Class/ResultSet.pm
@@ -2450,7 +2450,7 @@ sub related_resultset {
         "' has no such relationship $rel")
       unless $rel_info;
 
-    my ($from,$seen) = $self->_resolve_from($rel);
+    my ($from,$seen) = $self->_chain_relationship($rel);
 
     my $join_count = $seen->{$rel};
     my $alias = ($join_count > 1 ? join('_', $rel, $join_count) : $rel);
@@ -2548,7 +2548,7 @@ sub current_source_alias {
 # in order to properly resolve prefetch aliases (any alias
 # with a relation_chain_depth less than the depth of the
 # current prefetch is not considered)
-sub _resolve_from {
+sub _chain_relationship {
   my ($self, $rel) = @_;
   my $source = $self->result_source;
   my $attrs = $self->{attrs};
@@ -2569,11 +2569,28 @@ sub _resolve_from {
   # ->_resolve_join as otherwise they get lost - captainL
   my $merged = $self->_merge_attr( $attrs->{join}, $attrs->{prefetch} );
 
-  push @$from, $source->_resolve_join($merged, $attrs->{alias}, $seen) if ($merged);
+  my @requested_joins = $source->_resolve_join($merged, $attrs->{alias}, $seen);
+
+  push @$from, @requested_joins;
 
   ++$seen->{-relation_chain_depth};
 
-  push @$from, $source->_resolve_join($rel, $attrs->{alias}, $seen);
+  # if $self already had a join/prefetch specified on it, the requested
+  # $rel might very well be already included. What we do in this case
+  # is effectively a no-op (except that we bump up the chain_depth on
+  # the join in question
+  my $already_joined;
+  for my $j (@requested_joins) {
+    if ($rel eq $j->[0]{-join_path}[-1]) {
+      $j->[0]{-relation_chain_depth}++;
+      $already_joined++;
+      last;
+    }
+  }
+
+  unless ($already_joined) {
+    push @$from, $source->_resolve_join($rel, $attrs->{alias}, $seen);
+  }
 
   ++$seen->{-relation_chain_depth};
 
diff --git a/lib/DBIx/Class/ResultSource.pm b/lib/DBIx/Class/ResultSource.pm
index d6fd004..4eca0f8 100644
--- a/lib/DBIx/Class/ResultSource.pm
+++ b/lib/DBIx/Class/ResultSource.pm
@@ -893,7 +893,7 @@ sub add_relationship {
   }
   return unless $f_source; # Can't test rel without f_source
 
-  eval { $self->_resolve_join($rel, 'me') };
+  eval { $self->_resolve_join($rel, 'me', {}) };
 
   if ($@) { # If the resolve failed, back out and re-throw the error
     delete $rels{$rel}; #
@@ -1117,6 +1117,8 @@ sub _resolve_join {
     $self->throw_exception("No idea how to resolve join reftype ".ref $join);
   } else {
 
+    return() unless defined $join;
+
     my $count = ++$seen->{$join};
     my $as = ($count > 1 ? "${join}_${count}" : $join);