Whenever a new opportunity is being added, If the ExternalSystemId field is blank then go ahead and fire off the workflow action. If it's NOT blank then do not fire off the workflow
In the workflow condition, I have this
len(Field_Value('<ExternalSystemId>')) = 0 OR len(Field_Value('<ExternalSystemId>')) IS NULL
but it still fires off the workflow even though the external system id field has something in it.
Do you have any idea?
If I understand your question, you would need to write your default expression in the field definition (read the Default value and post default behavior). There are no workflow triggers for create (new Opportunity).