CODEWITHSUNDEEP
angularfirebasepromiserxjsangularfire2
David
David

Reputation: 3604

Return promise inside Observable

I've an Angular app using angularfire2 and I'm using a method which removes some information from a few different tables in firebase.

removeTeam(key: string) {
    const dataToRemove = {};
    dataToRemove[`teams/${key}`] = null;

    this.findMembersInTeam(key).subscribe(members => {
      members.forEach(member => {
        dataToRemove[`members/${member}/teams/${key}`] = null;
      });

      this.sdkDB.update(dataToRemove);
    });
  }

So what this does, basically is remove /teams/ and also, for every member in the team, remove the team, so remove /members//teams/.

What I do is retrieve the list of members inside a team, and as this is an observable, inside the subscribe I compose the "query" and execute it with this.sdkDB.update(dataToRemove)

This last method returns a Promise, and that is what I want to return as the result of the method removeTeam, is there a way to do that?

Thanks

Upvotes: 4

Views: 6850

Answers (2)

Lansana Camara
Lansana Camara

Reputation: 9873

IF sdkDB returns an Observable, import rxjs/add/operator/mergeMap and use flatMap or mergeMap (flatMap is just an alias of mergeMap) instead of subscribe.

This combines your observable streams.

removeTeam(key: string) {
    const dataToRemove = {};
    dataToRemove[`teams/${key}`] = null;

    return this.findMembersInTeam(key)
        .flatMap(members => {
            members.forEach(member => {
                dataToRemove[`members/${member}/teams/${key}`] = null;
            });

            return this.sdkDB.update(dataToRemove);
        })
        .toPromise();
  }

Upvotes: 4

Faly
Faly

Reputation: 13356

Try this:

import 'rxjs/add/operator/toPromise';

// ...

removeTeam(key: string) {
    const dataToRemove = {};
    dataToRemove[`teams/${key}`] = null;
    return this.findMembersInTeam(key)
               .toPromise()
               .then(members => {
                    members.forEach(member => {
                        dataToRemove[`members/${member}/teams/${key}`] = null;
                    });
                    return this.sdkDB.update(dataToRemove);
                });
}

Upvotes: 1

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