Angularfire: How do I read data only once?

Created on 4 Oct 2016 · 4Comments · Source: angular/angularfire

https://firebase.google.com/docs/database/web/retrieve-data#read_data_once

Is there such a once() function/parameter?

I'm not sure if this something AngularFire should do, Angular, RSJX, similar. Or there is a way to unsubscribe from the observable.

To give an example why I'm looking for this. I have the main page of the app that lists the last 10 items (newest first) that are for sale (books, chairs, etc.). I don't want this list to be updated as soon as another user creates a new item.
Am I worrying about something that shouldn't happen once I query by limitToLast: 10 for example?

Source

gianpaj

Most helpful comment

this works for me
constructor(public db: AngularFireDatabase
)
...
...
function someThing(){
return this.db.list("/dataBase").query.once("value")
}

regards

hcallejas on 31 May 2018

❤4 🎉3 👍3

All 4 comments

You'll find everything you need to know here #380

danielordonez on 4 Oct 2016

thanks @danielordonez !

gianpaj on 4 Oct 2016

this works for me
constructor(public db: AngularFireDatabase
)
...
...
function someThing(){
return this.db.list("/dataBase").query.once("value")
}

regards

hcallejas on 31 May 2018

❤4 🎉3 👍3

@hcallejas Thank you! That worked like a charm.

I thought I would share a more elaborate example for those that would like to see this in action.

backup() {
   this.afdb.object('/articles').query.once("value").then(data => {
      let timestamp = Math.ceil(new Date().getTime() / 1000);
      this.afdb.object(`/article_backups/${timestamp}`).set(data.val())
      alert(`Article backup created: ${timestamp}`)
   })
}