Firebase - Firestore - get key with collection.add() - firebase

Question

I am facing a problem with the new Firestore from Firebase.
Situation: I have a collection('room')
I create room with collection('room').add(room)
What I'm trying to do: I need to update a room.
For this, I use: collection('room').doc(ROOM_ID).update(update)
So I need to add ROOM_ID in the document in my collection:
|room
ROOM_ID
id:ROOM_ID,
someContent: ForTheQuery
Is there a possible way to achieve that?
An alternative is to create myself a generated ID with:
collection('room')
.doc(someId)
.set({
id: someId,
someContent: ForTheQuery
});
but i want to avoid it.

Answer 1

You can use doc() to create a reference to a document with a unique id, but the document will not be created yet. You can then set the contents of that doc by using the unique id that was provided in the document reference:
const ref = store.collection('users').doc()
console.log(ref.id) // prints the unique id
ref.set({id: ref.id}) // sets the contents of the doc using the id
.then(() => { // fetch the doc again and show its data
ref.get().then(doc => {
console.log(doc.data()) // prints {id: "the unique id"}
})
})

Answer 2

ANGULARFIRE:
get ID before add database:
var idBefore = afs.createId();
console.log(idBefore );
ANDROID FIRESTORE:
String idBefore = db.collection("YourCol").document().getId();

Answer 3

Firebase Javascript SDK:
Just use .id to get the key, here is an example using async/ await :
const KEYID = async() => (await fs.collection("testing").add({ data: 'test'})).id;

Answer 4

You can get the ID from the created document by using collection.ref.add(your item without id) and the response (res) will contain the new document reference created with the ID inside it. So get the ID by simply doing res.id.
createOne(options: { item: any, ref: AngularFirestoreCollection<any> }) {
const promise = new Promise((resolve, reject) => {
if (options.item) {
// Convert object to pure javascript
const item = Object.assign({}, options.item);
console.log('dataService: createOne: set item: ', item);
options.ref.ref.add(item)
.then((res) => {
console.log('dataService: createOne success: res: ', res);
resolve(res);
}).catch(err => {
console.error('dataService: createOne: error: ', err);
reject(err);
});
} else {
console.log('dataService: createOne: wrong options! options: ', options);
reject();
}
})
return promise;
}