In my implementation, I have multiple surveys, call them A, B, and C. In the field I would like to administer all 3 of those surveys to the same person. I do not, however, want to re-enter the identifying personal information on each form. A thorough look at the forums suggests that there is not yet a simple way to link between instances of different forms. One workaround that has been suggested is that I generate my own uuid which the enumerator will then re-enter on forms B and C, after it was generated for form A.
Because the identifier will need to be re-entered by hand, a relatively short id number is necessary. My idea was therefore to generate a 6 digit alphanumeric key, which downstream can be made unique to those 3 surveys only by concatenating on the date of data collection.
However I am unable to generate a random 6-digit alpha numeric key. In my survey table, i have:
name = "vid"
calculation = "once(uuid(6))"
From the help page I was under the impression that uuid(6) would suffice:
Without argument, returns a random RFC 4122 version 4 compliant UUID.
With an argument it returns a random GUID of specified length.
Can anyone explain why entering a value of [length] in this manner fails? This is also obviously a clunky solution to the problem of making a connection between surveys, but I haven't been able to find a better way with ODK. Thanks!