I've setup a Document Library with some lookup fields for "Vendor" which is a required field, I then have a workflow to copy that lookup field into another text field "_Vendor" so it then can be used in a Calculated column which is then in turn used for a lookup on another List.
The workflow works fine when doing edits to the files, but it fails to work properly when I have it "Start workflow automatically when an item is created" as it kicks off upon uploading the file and doesn't wait for you to enter the meta data and click save. Thus it gives me the error "Coercion Failed: Unable to transform the input lookup data intot he requested type" which would be fine if after uploading the file and pressing save it took that as a change to the file, but it is ignored.
I know if I set to copy the String it wouldn't give me an error but it would not copy anything meaningful across (0#;).
Using SharePoint Designer 2010, I've created the following Workflow:
Wait for document to be Checked-In then Set _Vendor to [%Current Item:Vendor%]
It seems that waiting for the document to be Checked-In isn't the same as wait until meta data is entered and you press save for the first time, so still get error.
I don't have this problem on Lists as it only recognised the creation event after all required fields have been set and you press save. So does anyone out there have a workaround for this?