CODEWITHSUNDEEP
angularfirebasefirebase-realtime-databaseobservableangularfire2
dibs
dibs

Reputation: 1077

How to iterate over a firebase2 list observable?

I have a list observable of objects that I am trying to iterate over to compare a list object property to a local variable.

I can loop over the objects in the list in a template but can't see how to in the component logic.

How can I do this outside of the template?

This is the closest I have gotten to a working iterator so far.

constructor(af: AngularFire) {
    this.competitors = af.database.list('/competitors');
}
this.competitors.forEach(competitor) {
    console.log(competitor);
}

I'm sorry if this is a question is poorly constructed, I am still quite new to Angular2 and Firebase.

Upvotes: 3

Views: 4245

Answers (3)

Govind Samrow
Govind Samrow

Reputation: 10187

Iterate with next in subscribe:

this.transactions.subscribe({
  next(competitors) {
    competitors.forEach(competitor => {
         console.log(competitor);
    });
  },
  error(err) { console.log('errors already caught... will not run'); }
})

Upvotes: 0

paweloque
paweloque

Reputation: 18904

You're working with Observables and not plain collections here. This means that you have to use the Observable primitives and simple looping over this.competitors will not work.

This this:

this.competitors.subscribe(competitor => console.log(competitor));

And by the way, there is a naming convention to name Observables with a $ at the end, so it would look the following way:

this.competitors$ = af.database.list('/competitors');

and:

this.competitors$.subscribe(competitor => console.log(competitor));

This will log the entire array of competitors. If you want to iterate over the elements, do something like the following:

this.competitors.subscribe(
    competitors => {
        competitors.map(competitor =>
            console.log(competitor)
        )
    });

Upvotes: 7

gsthina
gsthina

Reputation: 1100

this.competitors.forEach(competitor) {
    var competitorValue = competitor.val();
    console.log(competitorValue);
    competitorValue.forEach(sub){
        console.log(sub.val());
  }
}

This will let you parse through all the branches.

Upvotes: 0

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