how to execute observable in array Angular?

Question

I have an array variable named users. it contains users id elements.

users=[uid1, uid2, uid3];

and I want to map this array and get users info from Firestore like this:

let userInfo;
userInfo = users.map((element:any) => {       
    if (element){
        this.afsService.doc(`user/${element}`).subscribe(user => {
            return {...user}
        });    
    }
...

when this code worked, I got this error:

You provided 'undefined' where a stream was expected. You can provide an Observable, Promise, Array, or Iterable.

so my question; how to execute Observable in array iterate?

Is that your actual code? And please share your template too. And what gives this error? — Eldar
– Eldar, Commented Dec 13, 2019 at 18:51

necati · Accepted Answer · 2019-12-15 15:11:35Z

1

thaks @Moxxi I ca run my codes with helps. this my codes; forkJoin not work so I used combineLatest instead of it. anf filter(Boolean) worked with pipe.

 this.usersInfo$= combineLatest(
          users.map((user:any)=>this.afs.doc(`users/${user.uid}`).valueChanges()
        )).pipe(map(x=>x.filter(Boolean)))

answered Dec 15, 2019 at 15:11

necati

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Comments

MoxxiManagarm · Accepted Answer · 2019-12-13 20:54:41Z

0

You can map your id's to an array of observable and execute them with an combination operator liek forkJoin or combineLatest. The subscription will bring you an array of the results

userIds = [uid1, uid2, uid3];

userInfos$ = forkJoin(userIds.filter(Boolean).map(userId => this.afsService.doc(`user/{userId}`)));

userInfos$.subscribe(console.info);

edited Dec 13, 2019 at 20:54

answered Dec 13, 2019 at 18:52

MoxxiManagarm

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3 Comments

Heretic Monkey Over a year ago

Answers with explanation of code presented typically get upvoted more often that those which simply present code.

The Dead Man Over a year ago

@HereticMonkey exactly bro

necati Over a year ago

This codes are presented. I though I can easily explain what I do. With this way.Thanks for help.

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