firebase-collection : update or add ???

[pithon.ph...@gmail.com]

Hi,

I use element firebase-collection for display lines in grid

<firebase-collection id="idfirebase" location="https://........." data="{{dbelementss}}"></firebase-collection>

but... how to create or update lines ? I don't find the right solution

for create I use : this.$.idfirebase.add(line);

for update a line ?

ideas ???