Retrieve a string value from an Observable containing strings

There is an Observable called this.downloadURL that retrieves a specific string value after querying the database:

https://i.sstatic.net/pWmVk.jpg

The goal is to obtain this value in the following method:

 
//Upload a new picture to the database as a profile picture
uploadBetPicture(event) {
  const id =
    "bet_" +
    Math.random()
      .toString(36)
      .substring(2) +
    "_Photo";
  this.ref = this.afStorage.ref(id);
  this.task = this.ref.put(event.target.files[0]);
  this.downloadURL = this.task.downloadURL();
  
  //Above code successfully stores the picture and sets the observable

  //The error occurs at this line
  this.photoUrl = this.downloadURL.value;
}

Despite seeing the value in the console, attempting to access it results in an error message:

Property 'value' does not exist on type 'Observable'.

It's important to note that the storing process functions correctly since the value can be retrieved.

Answer №1

When dealing with this.task.downloadURL(), which is an Observable containing your downloadURL, you must subscribe to it in order to access the actual value.

Give this a try:

uploadBetPicture(event) {
  const id =
    "bet_" +
    Math.random()
    .toString(36)
    .substring(2) +
    "_Photo";
  this.ref = this.afStorage.ref(id);
  this.task = this.ref.put(event.target.files[0]);
  this.task.downloadURL()
    .subscribe(value => this.photoUrl = value);
}

PLEASE NOTE:

The value returned by the Observable may contain additional keys, so it's recommended to log the value within the subscribe block first and then access the appropriate key from the value object.

Answer №2

Exploring the RxJs documentation reveals the power of Angular's reactive form, allowing you to go beyond simple subscription and waiting for asynchronous callbacks.

Take, for example, the ability to query for the first value in the observable:

YourObservable.first()

http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#instance-method-first



Alternatively, you can retrieve the last value:

YourObservable.last()

http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#instance-method-last


For comprehensive information on Observables, refer to the complete documentation here:

http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html

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