1. Create a new field in the IP form for each of your dropdown.
2. Setup a rule of 'Action' type on your dropdown as follows:
A. Set Condition : None and Action as Set a field's value. B. In the Field box: select the field which you created newly in step#1. C. In the Value box > click fx > click Insert a field > select the data source (secondary) which you used to bind your dropdown. D. Select displayname and then hit Filter Data... button. E. Click Add... button. F. Set value 'is equal to' Your Dropdown field. G. Hit OK on all the open dialog box. H. Execute the form locally.
A. Set Condition : None and Action as Set a field's value.
B. In the Field box: select the field which you created newly in step#1.
C. In the Value box > click fx > click Insert a field > select the data source (secondary) which you used to bind your dropdown.
D. Select displayname and then hit Filter Data... button.
E. Click Add... button.
F. Set value 'is equal to' Your Dropdown field.
G. Hit OK on all the open dialog box. H. Execute the form locally.
Now, when you select a value in your dropdown, you see the corresponding display name in your new field. Once it's confirmed, you can remove this field from your form so that users don't see it.
After that, promote this field so that it's shown in the library. Hope it helps. Thanks, Ashish Gupta
Ed Price - MSFT edited Original. Comment: Updated title per guidelines. Adding tags.
"C. In the Value box > click fx > click Insert a field > select the data source (secondary) which you used to bind your dropdown."
Aren't you missing the part in this walkthrough where you explain that the drop-down list box has to be created with the settings "Get choices from an external data source"?
You can just use a drop-down list box with "Enter choices manually".