So, I’ve continued investigating my problems updating a SharePoint Workflow Task. I decided to learn about event receivers, as this is what the message was about.

Event receivers, well, receive events that happen on an item, and process them. I listed the ones on my workflow task list with the following code:

for (int j = 0; j < myList.EventReceivers.Count; j++)
{
SPEventReceiverDefinition d = myList.EventReceivers[j];
Log (d.Assembly + " - " + d.Class + " - " + d.Data + " - " + d.Filter + " - " + d.Name + " - " + d.Type.ToString());
}

This gave the the results:

31/08/2006 11:13:57 – Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c – Microsoft.SharePoint.Workflow.WorkflowTaskUpdateEventReceiver – – – – ItemAdding

31/08/2006 11:13:57 – Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c – Microsoft.SharePoint.Workflow.WorkflowTaskUpdateEventReceiver – – – – ItemUpdating

31/08/2006 11:13:57 – Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c – Microsoft.SharePoint.Workflow.WorkflowTaskUpdateEventReceiver – – – – ItemDeleting

31/08/2006 11:13:57 – – – – – – 32767

It turns out that there is an easier way of list the event receivers, but dumping to a log file works. Interestingly, he also had the same 32767 result, which is weird. It’s (2^15)-1, so presumably the highest value that can be represented by a 16bit signed integer – but what is it doing in my log?

Anyway, I reckon that the ItemUpdating event receiver is killing my update – but don’t effing know why.

Incidentally, this is a good article demonstrating event receivers. Shame about the bugs they’re finding, though.

Problems doing the simplest things. I want to update a task created by the CreateTask activity, when the activity is changed. I have the following function, which is run when the Task list item is edited…

private void onTaskChanged1_Invoked(object sender, ExternalDataEventArgs e)
{
SPWeb mySite = new SPSite(workflowProperties.SiteId).OpenWeb(workflowProperties.WebId);
SPList myList = mySite.Lists[workflowProperties.TaskListId];
SPListItem myTask = myList.GetItemById(TaskBeforeProperties.TaskItemId);
SPUser myUser = mySite.AllUsers[e.Identity];
myTask["Assigned To"] = myUser;
myTask.Update();
}


Everything seems okay, but when I call myTask.Update(), I get the exception “An event receiver has cancelled the request.” And I’m damned if I know why.