Add calculated field to my form?

I have a form that can be submitted and edited, I need to add calculated field updated_at that should be the timestamp. this will allow me to query submissions that have changed for a period of time.
The submissions will be done from the browser.
I have used this function
https://docs.opendatakit.org/form-operators-functions/?highlight=now#now
but it only gives dateTime on a format that is hard to compare

I am using ODK within Kobotoolbox

If you want date and time in a different format you could always use different operators such as the ones in the ‘Converting dates and time’ section of the form operators link you posted.

Or, an alternative approach would be to do this: http://support.kobotoolbox.org/en/articles/1992079-how-to-create-sequential-unique-serial-numbers

Whichever operators you use, you will need to bear in mind the gotchas - https://docs.opendatakit.org/form-logic/#when-expressions-are-evaluated - as each time the form is opened the values will recalculate unless ‘once’ is used.

There’s timestart and audit logging meta question on the KoBo Collect app, but don’t think that’s available on the browser.

Does that help? I hope I haven’t misunderstood your question!

1 Like


Thanks @nat, this really helps in getting something close to timestamp, but it still relies on the fact that the submitting computer has the correct time. if the clock is behind, then my server requesting the latest submission might miss the submission