Unknown response for document read in Cloud-Firestore

Question

Currently, I play a bit with firebase and wanted to implement an increment and decrement mechanism. The current value should be stored in Cloud Firestore.

So I made a reference to it and check for the id and if the reference exists.

When I try to run the code I get back the correct id and payload.exist is true .

If I want now to add a check if the number is 0 to delete it, the Document Snapshot is unknown and so I can't find the property or call delete/update on the document.

Would be great if anyone could tell me how I get access to the data in the Document. Thanks! :)

Here you can find the attached code:

constructor(private db: AngularFirestore) { }
private updateNumberCount(count: number) {
const reference = this.db.collection('counting').doc('documentId');

reference.snapshotChanges().pipe(take(1)).subscribe(item => {
  console.log(item.payload.id);     // the correct id is displayed
  console.log(item.payload.exists); // -> is true

  const quantity = (item.currentNumber || 0) + count;
  if (quantity === 0) {
    // if it is 0 it should be deleted
    item.delete();
  } else {
    // if it not exists it should be created or updated
    item.update({ currentNumber });
  }
});
}

Answer 1

As explained in the doc , snapshotChanges() returns an Observable of data as a DocumentChangeAction .

And for the DocumentChangeAction type :

A DocumentChangeAction gives you the type and payload properties. ... The payload property is a DocumentChange which provides you important metadata about the change and a doc property which is the DocumentSnapshot .

So the following should do the trick (untested):

const quantity = (item.payload.doc.data().currentNumber  ...

Answer 2

I could get the data back by calling .ref.get().then() on the referance to the document.

const reference = this.db.collection('counting').doc('documentId');

reference.ref.get().then(doc => {
// here I can call **.data** on it to receive the data. 
   doc.data().currentNumber 
}

Thank you for all the help! :)