--- nfo/perl/libs/Tangram/Storage.pm	2002/12/16 05:08:22	1.3
+++ nfo/perl/libs/Tangram/Storage.pm	2003/04/24 00:21:27	1.9
@@ -247,6 +247,33 @@
     return sprintf "%d%0$self->{cid_size}d", $id, $class_id;
   }
 
+
+# create global unique identifers using Data::UUID
+sub make_guid 
+  {
+    my $self = shift;
+
+    my $guid;
+
+    # try to use Data::UUID first ...
+    eval("use Data::UUID;");
+    if (!$@) {
+      my $ug = Data::UUID->new();
+      $guid = $ug->create_str();
+      
+    # ... if this fails, try to fallback to Data::UUID::PurePerl instead ...
+    } else {
+      eval("use Data::UUID::PurePerl;");
+      if (!$@) {
+        $guid = Data::UUID::PurePerl::generate_id();
+      } else {
+        croak "couldn't create globally unique identifier";
+      }
+    }
+    
+    return $guid;
+  }
+
 sub make_1st_id_in_tx
   {
     my ($self) = @_;
@@ -455,6 +482,9 @@
     return $self->id($obj)
       if $self->id($obj);
 
+  	# insert global unique identifier in object to persist across re-deploys 
+	  $obj->{guid} = $self->make_guid();
+	
     $saving->insert($obj);
 
     my $class_name = ref $obj;
@@ -484,7 +514,7 @@
 
 	  if ($Tangram::TRACE) {
 		printf $Tangram::TRACE "executing %s with (%s)\n",
-		$cache->{INSERTS}[$i],
+		$cache->{INSERTS}[$i], 
 		join(', ', map { $_ || 'NULL' } @state[ @{ $fields->[$i] } ] )
 	  }
 
@@ -675,6 +705,7 @@
 	my $row = _fetch_object_state($self, $id, $class);
 
     my $obj = $self->read_object($id, $class->{name}, $row);
+    return undef unless defined $row;
 
     # ??? $self->{-residue} = \@row;
 
@@ -692,6 +723,7 @@
     my $class = $self->{schema}->classdef( $self->{id2class}{ int(substr($id, -$self->{cid_size})) } );
 
 	my $row = _fetch_object_state($self, $id, $class);
+    return undef unless defined $row;
     _row_to_object($self, $obj, $id, $class->{name}, $row);
 
     return $obj;
@@ -763,6 +795,11 @@
 
 	$sth->execute($self->{export_id}->($id));
 	my $state = [ $sth->fetchrow_array() ];
+	croak "no object with id $id" unless (@{$state});
+	unless (@$state) {
+		return undef unless $sth->err;
+		croak "error during load of object id=$id: $sth->err";
+	}
 	$sth->finish();
 
 	return $state;