Flutter 和 Firestore：如何从添加 function 中获取文档 ID？

Question

I added a document to Firestore. How can I get the document Id of my added document? I want to save it to a variable.

Btw. I'm using this for a web app if this Is important.

FirebaseFirestore.instance.collection('room').add({
    'name': _name,
    'points': 0,
});

Answer 1

Do this

User user = FirebaseAuth.instance.currentUser;

FirebaseFirestore.instance.collection('room').add({
    'id': user.uid,
    'name': _name,
    'points': 0,
});

Answer 2

Calling CollectionReference.add returns a Future<DocumentReference> , so you can get the ID from that:

var newDocRef = await FirebaseFirestore.instance.collection('room').add({
    'name': _name,
    'points': 0,
})
var newDocId = newDocRef.id

---

If you want to store the ID inside the document, it's better to first create the DocumentReference by calling CollectionReference.doc() without paramters:

var newDocRef = FirebaseFirestore.instance.collection('room').doc();
var newDocId = newDocRef.id
newDocRef.set({
    'id': newDocId,
    'name': _name,
    'points': 0,
})

Answer 3

Add .then method at the end.

Do what ever you need with docRef.

FirebaseFirestore.instance.collection('room').add({
    'name': _name,
    'points': 0,
}).then(function(docRef) {
    console.log("Document written with ID: ", docRef.id);
})

Answer 4

The add method on CollectionReference returns a Future<DocumentReference> . [ Documentation ]

Future<DocumentReference> add(Map<String, dynamic> data) async {
  final DocumentReference newDocument = doc();
  await newDocument.set(data);
  return newDocument;
}

So, try this:

FirebaseFirestore.instance.collection('room')
  .add({
    'name': _name,
    'points': 0,
  })
  .then((docRef) => print(docRef.id));