[Lizmap] Sum for selection

[Paolo Cavallini]

Hi all,
we would need a function apparently not present in the base functions:
unce selected a series of features, display not only the data from the
table, but also the sum for some variables.
I'm wrapping my head around this, and I cannot find a clean solution.
I see three main routes:
* through QGIS expressions (unsure it is feasible)
* with PostGIS views (how to show only selected?)
* with JavaScript.
The last one seems the most promising: am I correct? Any hint on how to
start?
Thanks for any suggestion.
Cheers.
-- 
Paolo Cavallini
www.faunalia.eu - QGIS.org
training, support, development on QGIS, PostGIS and more