CODEWITHSUNDEEP
javascriptangularfirebasegoogle-cloud-firestore
Abdullah
Abdullah

Reputation: 37

Property 'then' does not exist on type Observable<QuerySnapshot<DocumentData>>

db.collection("cities").get()
  .then(function(querySnapshot) {
    querySnapshot.forEach(function(doc) {
      // doc.data() is never undefined for query doc snapshots
      console.log(doc.id, " => ", doc.data());
  });

I'm trying to read multiple document of a collection, but getting error on then. Please help me to sort out this.

Upvotes: 1

Views: 1569

Answers (1)

julianobrasil
julianobrasil

Reputation: 9357

If you want to treat is as a promise, you can convert it to a promise. This isn't a hack, once there's only one emission being produced by get(). But Firebase expected you to deal with the stream that's coming out from get() though. Anyway, to convert it to a promise:

db.collection("cities").get().toPromise()
  .then((querySnapshot: QuerySnapshot<DocumentData>) => {
    querySnapshot.forEach((doc: any) => {
      // doc.data() is never undefined for query doc snapshots
      console.log(doc.id, " => ", doc.data());
  });

If you decide to deal with the streaming coming out from get(), as Firebase API expected you to:

db.collection("cities").get()
  .subscribe((querySnapshot: QuerySnapshot<DocumentData>) => {
    querySnapshot.forEach((doc: any) => {
      // doc.data() is never undefined for query doc snapshots
      console.log(doc.id, " => ", doc.data());
  });

[UPDATE] 1: Based on the docs, there's a new API for getting the snapshots, using the onSnapshot method:

db.collection("cities")
  .onSnapshot((querySnapshot: QuerySnapshot<DocumentData>) => {
    querySnapshot.forEach((doc: any) => {
      // doc.data() is never undefined for query doc snapshots
      console.log(doc.id, " => ", doc.data());
  });

Upvotes: 4

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