documentreference.get().then((datasnapshot code example

Example 1: get one document based on id in firestore

//retrieve one document and save it to userDetails
const [userDetails, setUserDetails] = useState('')
db.collection('users').doc(id).get()
        .then(snapshot => setUserDetails(snapshot.data()))

Example 2: get doc id firestore

const racesCollection: AngularFirestoreCollection;
return racesCollection.snapshotChanges().map(actions => {       
  return actions.map(a => {
    const data = a.payload.doc.data() as Race;
    data.id = a.payload.doc.id;
    return data;
  });
});