Unique Identifiers using select_one_from_file

I would like to set up a survey that allows a data collector to select from a list of unique identifiers that once selected, the identifier can not be used again to prevent duplicates. An idea I had is that the data collector could initially select their name from a drop down, and then using select_one_from_file, could select from a list of identifiers unique to the data collector. But ultimately looking for any solutions.


I am implenting this another way. I keep the unique IDs at the server backend. So when the data submission is done to the central server, a script picks up a unique ID, assigns it to the submission, and sends it to the mobile number of the field officer via SMS. This is all done in realtime. So the field officer hands over the ID to the household straightaway. But do note that this happens outside ODK.

Pros: Handling unique IDs at the backend is much easier, instead of loading separate list of IDs with separate field officers. Secondly, the ID list is never under- or over-utilized, as it may happen with giving local lists to individual field staff. A common backend will manage it automatically.

Cons: Its a challenge for offline data collection, for having no cell connection. Sometimes the area does have mobile signals but only no data, so sms and voice still work. It works there. But if no telco at all, then sms won't reach field staff, and it becomes a minor issue. Additionally, you may need some expertise in setting up the backend i mentioned. But its just one time effort.

Feel free to ping for more help.