I have an External Content type connected to a USP on an External SharePoint 2010 list using Business Connectivity Services. In a second associated list, I have no problem looking up and displaying an external data column and associated columns on the list view. However, in Nintex Forms, only the source column can be seen when I configure an External Data column. There is a section for Additional Fields available, but I can't figure out how to get these to show in the form. See the example below:
The result I am looking for is to enable a user to select a project number from an External Data column, and to show the project client and description on the form. Any help in accomplishing this is appreciated.
Took me ages to figure this out too, but surprisingly simple in the end. Just add a Label or TextBox control on the form, then for the text, just insert a reference, and any of the External Data columns you made available can be added. See screenshot where Contact Id was the external data column and you can see the secondary columns available to be inserted as well.
This next screenshot shows what it looks like on the form after you've added them. Note that when editing (in the actual published form), the data in the fields will only get refreshed once the form is saved. Haven't worked out how to display them immediately when the Contact Id is changed.
Hope that's useful!