How to setup workflow that would run only when a certain field is changed

Question

I'm struggling with this one. Of course I've seen the guide from http://office.microsoft.com/en-gb/sharepoint-designer-help/watch-this-run-a-workflow-when-a-specific-field-changes-HA010256419.aspx which has been referenced by many. This example is based on SP2007, I'm using SP2010 (SP2010 Designer) and just cant get this to work in the same way...

What's happening?;

If "before" field is blank, it gets updated to match "current" - But I get an email generated stating the field has changed.

If "before" field matches "current", no further action and workflow completes - No email

If "current" field is changed, I get an email - which is what I'm looking for it to do.

I just can't get this to stop mailing me when there's a blank field - quite frustrating, tried re-working/re-formatting the workflow many times now...

I think I just need to understand how to "nest" the "steps" (or "If" statements) in a way that I can control the workflow stopping after updating the blank "before" field.

Any ideas?

Answer 1

You're going to need to create an event receiver for the list in question, using the OnItemChanging (because I don't believe BeforeProperties exist for OnItemChanged). Then, once you've validated the list item in question, you'd call the workflow using these steps:

http://www.sharepointkings.com/2008/09/how-to-start-workflow-programmatically.html

This ought to get you started. My recommendation is to create the workflow first and confirm that it's working, and then and only then attempt to call it from the event receiver.