Xml-external Gps change value

hi to all
I have this goal:
I manage a participatory research on a place, people who pass can use an enketo form of which they find the indications.
Within this form they must also enter the GPS position where they make an observation and describe the place where they made it and leave a predetermined signal with a code.
Researchers have a control form where they go to the site and add details to the observations of the previous form.
The first form for ordinary citizens is used in enketo, and we know what the problems are in entering the GPS position with good accuracy.
I wish the researchers in their control form could verify the GPS position and improve it, as they use odkcollect.
But if I add such a line

type: geopoint
name: C_location
label: location
appeareance: Placement-map
calculation: instance(‘first_form’)/root/data[P_id = current()/…/C_id]/P_location

non-GPS position changes are not made.
The only possibility is to make an additional GPS point field?

Or the technique is to use the string calculation in “default”

Thank you

Hello @bonushenricus,
a calculation will always get activated, so will overwrite any entry. Except you use once(…). Default should also work.

Your citizen project seems interesting, maybe you could share more information with the community, please?

1 Like

Thank you @wroos! Using “once ()” works !!
Is there a place in this forum to explain projects?
However, I also write here: it is a research on Brown Marmorated Stink Bug (BMSB), Halyomorpha halys, carried out within an Agriculture Supported Community (ASC) cooperative visited by many citizens of the city of Bologna. If citizens see a BMSB egg mass, with the app they can report it to the researchers, and the researchers will keep it monitored, to understand the parasitization index.


@bonushenricus, you should also be able to use this post if you wish to explain more about your project. The community could benefit!