Observing single value in DB: No update on change

[JaneDawson]

When I subscribe to a single value in my Firebase DB, the observable doesn't trigger when the value changes.

In the following example the "balance" node is of type "Number".

getBalanceStream(userId){
    this.db.object('/users/'+userId+'/balance').subscribe( bal=> {
      this.balance= bal.$value;
    }
  }

When the user's balance changes in the database, the arrow function is not triggered. this.balance doesn't get updated.

When I use regular AngularFire2 it works as expected.

[adriancarriger]

I've been able to reproduce your issue here with a demo.

If you click the button, the data is saved and written to Firebase, but it is not displayed in the ui.

I'll be working on this one. Thanks for posting!

[JaneDawson]

Thank you! I appreciate that.

[adriancarriger]

This should be fixed in version 4.1.5 ..let me know if you still experience any issues. Thanks!

[JaneDawson]

Thank you for updating. I just tested it. Unfortunately it's still the same as before. Observing a single value doesn't work properly and sticks to the initial value.

[adriancarriger]

Hi @JaneDawson, here's a working demo (source code) using angularfire2-offline version 4.1.5

When I was making the demo my package.json had "angularfire2-offline": "^4.1.5" which resolved to version 4.2.0 (a version that was published unintentionally). By changing the package.json to "angularfire2-offline": "4.1.5" the issue was fixed.

You can check which version your app is running by going to:

your-project/node_modules/angularfire2-offline/package.json

Let me know if this solves your issue. Thanks!

[JaneDawson]

That fixed it for me, as well. Works just fine now. Thank you, @adriancarriger. I appreciate it!

[adriancarriger]

Awesome, glad it's working now! 👍

[JaneDawson]

Unfortunately, I have to reopen this issue. Everything works fine, except if the value of the subscribed attribute is 0.

If in the following example the account balance object ..users/'userId'/balance' is 0 in the database, then bal.$value becomes undefined. This shouldn't be, since 0 is a valid value for the balance.

getBalanceStream(userId){
    this.db.object('/users/'+userId+'/balance').subscribe( bal=> {
      this.balance= bal.$value;
    }
  }

[JaneDawson]

Anything new here?

[adriancarriger]

Hi @JaneDawson, thanks for reopening! I'll be looking into this!

[adriancarriger]

I can confirm this issue and have made a demo (with code). When the counter gets to zero no number is shown, however the value in the database is zero. I'll be working fixing this!

[JaneDawson]

Thank you. I appreciate that. Works well now!

[adriancarriger]

Awesome, glad it's working! 👍