Ionic 4 / firebase RTDB / wait that a field in table is modified / update a list

Hello everyone,

I have a firebase RTDB with description:

var postData = {

** flag_upd_templ: 1,**

** key_upd_templ: xxxx**

** };**

1- First I set flag ‘flag_upd_templ’ to ‘1’
2- another application check this flag and set it to ‘0’

Then I have to wait for this flag to be set ‘0’ to proceed more data…

I’ve tried the:
this.db.database.ref(’***********’).equalTo(0)

but how can I embedded in a function that would wait for it?

Thanks.

This sounds like you’re trying to reinvent push notifications.