CODEWITHSUNDEEP
angularjsionic-frameworkfirebasefirebase-realtime-databaseionic2
Kyanite
Kyanite

Reputation: 746

How to store the result of a Firebase query to a variable from a promise?

I'm new to angular and still trying to get the hang of promises.

I have an ItemDetail class:

@Component({
  templateUrl: 'build/pages/item-detail/item-detail.html',
  providers: [Auth]
})
export class ItemDetailPage {
  private title;
  private description;
  private author;

  constructor(private navParams: NavParams, private _auth: Auth) {
    this.title = this.navParams.get('item').title;
    this.description = this.navParams.get('item').description;

    _auth.getUser(this.navParams.get('item').author).then(function(snapshot){
      console.log("ayyy lmao = " + JSON.stringify(snapshot.child(navParams.get('item').author).val().email));
      this.author = JSON.stringify(snapshot.child(navParams.get('item').author).val().email);
    });

    console.log("thisAuthor = " + this.author);
    }

}

I'm trying to store the e-mail retrieved from the database as the author variable. Even though it is output correctly in the console, its value does not actually get assigned to the variable outside of the promise. However I think where I'm encountering an issue is to do with the promise, which is a concept I'm still trying to get my head around.

The getUser method in the Auth class is as follows:

  getUser(uid: string): any {
    return firebase.database().ref('/userProfile').orderByKey().equalTo(uid).once("value", function(snapshot){});
  }

If there is a better way to do this (without promises), that'd be a solid alternative too.

Thanks!

Upvotes: 0

Views: 553

Answers (2)

Aaron Saunders
Aaron Saunders

Reputation: 33345

A few things...

A better way to get the user profile information is to use the uid as the key when you insert the object

firebase.database().ref('/userProfile/' + uid).once("value", function(snapshot){});

If you use => fat arrows, the binding is done for you in ionic2

  _auth.getUser(this.navParams.get('item').author)
     .then((snapshot) => {
         // THIS WILL BE WHAT YOU EXPECT...
      });

Upvotes: 0

MarkoCen
MarkoCen

Reputation: 2324

seem like the promise works fine, but this point to wrong instance, use Function.prototype.bind to bind this to ItemDetailPage:

function successHandler(snapshot){ ... };

_auth.getUser(this.navParams.get('item').author).then(successHandler.bind(this));

Upvotes: 1

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