Fix multiple bugs related to Singleton workflows:

Can't use undef in a where clause.
    Have to use the same JSON encoding in all places.
Added tests for singleton workflow instances.

docs/changelog/7.x.x.txt

@@ -38,6 +38,8 @@
  - fixed: Thingy Things can now have no fields and still be functional.
  - fixed: Can no longer buy badges from receipt or direct link page if quantity is empty
  - fixed: Tickets on add to badge screen now show the time at the event's timezone
+ - It was possible to run multiple singleton workflows at the same time.
+
 7.5.22
  - fixed: Layout template now gets prepared correctly
  - fixed: When user does not have permissions to search/edit a thing a proper error is shown.

lib/WebGUI/Workflow/Instance.pm

@@ -61,12 +61,17 @@ sub create {
 	my ($class, $session, $properties, $skipRealtime) = @_;
 
     # do singleton check
-	my ($isSingleton) = $session->db->quickArray("select count(*) from Workflow where workflowId=? and
-    mode='singleton'",[$properties->{workflowId}]);
-	my $params = (exists $properties->{parameters}) 
-            ? JSON->new->utf8->canonical->encode({parameters => $properties->{parameters}})
-            : undef;
-	my ($count) = $session->db->quickArray("select count(*) from WorkflowInstance where workflowId=? and parameters=?",[$properties->{workflowId},$params]);
+    my $placeHolders = [$properties->{workflowId}];
+	my ($isSingleton) = $session->db->quickArray("select count(*) from Workflow where workflowId=? and mode='singleton'",$placeHolders);
+    my $sql = "select count(*) from WorkflowInstance where workflowId=?";
+	if (exists $properties->{parameters}) {
+        push @{ $placeHolders }, JSON->new->utf8->pretty->encode({parameters => $properties->{parameters}});
+        $sql .= ' and parameters=?';
+    }
+    else {
+        $sql .= ' and parameters IS NULL';
+    }
+	my ($count) = $session->db->quickArray($sql,$placeHolders);
     if ($isSingleton && $count) {
         $session->log->info("An instance of singleton workflow $properties->{workflowId} already exists, not creating a new one");
         return undef

t/Workflow/Instance.t

@@ -42,23 +42,24 @@ my $session         = WebGUI::Test->session;
 #----------------------------------------------------------------------------
 # Tests
 
-plan tests => 8;        # Increment this number for each test you create
+plan tests => 11;        # Increment this number for each test you create
 
 #----------------------------------------------------------------------------
 # put your tests here
 
-###############################################################################3
+###############################################################################
 #
 # create a workflow instance
 #
-###############################################################################3
+###############################################################################
 
 my $wf = WebGUI::Workflow->create(
     $session,
     {
         title => 'WebGUI::Workflow::Instance Test',
         description => 'Description',
-        type => 'None'
+        type => 'None',
+        mode => 'singleton',
     }
 );
 isa_ok($wf, 'WebGUI::Workflow', 'workflow created for test');
@@ -66,9 +67,6 @@ isa_ok($wf, 'WebGUI::Workflow', 'workflow created for test');
 # create an instance of $wfId
 my $properties = {
     workflowId=>$wf->getId,
-    methodName=>"new",
-    className=>"None",
-    parameters=>'encode me',
 };
 my $dateUpdated = time();
 my $instance = WebGUI::Workflow::Instance->create($session, $properties);
@@ -79,12 +77,21 @@ is($instance->get('priority'), 2, 'Default instance priority is 2');
 cmp_ok(abs ($instance->get('lastUpdate')-$dateUpdated), '<=', 3, 'Date updated field set correctly when instance is created');
 
 ##Singleton checks
+my $otherInstance = WebGUI::Workflow::Instance->create($session, $properties);
+is ($otherInstance, undef, 'create: only allows one instance of a singleton to be created');
 
-###############################################################################3
+$instance->set({ 'parameters' => {session => 1}, });
+$otherInstance = WebGUI::Workflow::Instance->create($session, {workflowId => $wf->getId, parameters => { session => 1,} });
+is($otherInstance, undef, 'create: another singleton instance can not be created if it the same parameters as a currently existing instance');
+$otherInstance = WebGUI::Workflow::Instance->create($session, {workflowId => $wf->getId, parameters => { session => 2,}});
+isnt ($otherInstance, undef, 'create: another singleton instance can be created if it has different parameters');
+$otherInstance->delete;
+
+###############################################################################
 #
 #  getWorkflow
 #
-###############################################################################3
+###############################################################################
 
 my $instanceWorkflow = $instance->getWorkflow;
 is($instanceWorkflow->getId, $wf->getId, 'getWorkflow returns a copy of the workflow for the instance');
@@ -95,5 +102,5 @@ is($instanceWorkflow->getId, $wf->getId, 'getWorkflow, caching check');
 #----------------------------------------------------------------------------
 # Cleanup
 END {
-    $wf->delete;  ##Deleting a Workflow deletes its instances, too.
+    #$wf->delete;  ##Deleting a Workflow deletes its instances, too.
 }