How does the backend edit or update geofence's attributes?
I believe those are stored in the attributes field.
Quite so, I need to add a new attribute to this JSON field so that I can identify a geofence by his type so I need to add a new key value pair, let's say "geofenceType": "Danger Zone" different from the three choice that the web allows (color, speed limit and polyline distance) but actually in backend there is no way to edit this JSON attribute field adding a new key value pair. Any idea will be well received
You can add as many attributes as you want. I'm also not sure what you mean by "in backend there is no way to edit this JSON attribute". It's simply an incorrect statement.
In the relational scheme a geofence it's defined by an id, name, description, area, attributes and calendarid, this attributes column as a JSON type. The model described in the tracker server doesn't have an attribute field neither getter and setter so, how the backend actually set and update color, speed limit and polyline distance of each geofence?