[cloud_firestore] Need id generator like createId() function in AngularFire

[eugvb]

In some cases I need generate id before store document in firestore.
In AngularFire there is function createId()
In Flutter I can import 'package:cloud_firestore/src/utils/auto_id_generator.dart' (since 0.12.8, push_id_generator before)
and then use AutoIdGenerator.autoId()
But it's not true way, because I should import implementation files from another package.

[cmkweber]

CollectionReference has an add method which returns an auto-generated ID:

https://pub.dev/documentation/cloud_firestore/latest/cloud_firestore/CollectionReference/add.html

[BondarenkoStas]

@eugvb Please report if the comment above solved your issue.

[eugvb]

Maybe it is not perfect way, but I persist Document Id inside it. So I need generate id before calling add() method.

[tantzygames]

I use:
String id = reference.document().documentID;

Then apply the id within the document and any other documents, then save.

There is an issue with both this and add() that is only occurring recently. iOS is creating a different format of id than Android, where they used to be the same. So you may be better off creating your own id system...

Edit: I notice this was new to 0.12.7 but is now consistent across iOS and Android in 0.12.8. Unfortunately the new format of id's are no longer chronological so I'm using the old PushIdGenerator for id's that I prefer to be chronological.

[eugvb]

Ok, storing Document Id in itself not good practice. So in this case no need for id generation.

But what about transaction or batch writes?
For example, I want to add document to collection and then store it Id in other document

Firestore.instance.runTransaction((tx) async {
  String docId = 'docId';//It should be generated
  await tx.set(Firestore.instance.collection('collection').document(docId), {'some':'data'});
  //There i need docId to store it in other Document
  await tx.set(Firestore.instance.collection('collection2').document('DocumentId2'), {'docId':docId});
});

Transaction doesn't have add method, so I need use set with generated id.
With Batch write situation is similar.

[cmkweber]

Use document without passing a path:
https://pub.dev/documentation/cloud_firestore/latest/cloud_firestore/CollectionReference/document.html
This generates a unique id without setting it within database like add does.

[eugvb]

It is solution, thank you

[sultanmyrza]

I know its late but here is what I did

String randomId() {
    var _randomId = Firestore.instance.collection('').document().documentID;
    print(randomId());
    return _randomId;
}

[Limitless-Kode]

I know its late but here is what I did

String randomId() {
    var _randomId = Firestore.instance.collection('').document().documentID;
    print(randomId());
    return _randomId;
}

Can this produce a unique ID? I am thinking it would somehow create an ID that already exists.

[cmkweber]

They are unique: https://stackoverflow.com/questions/46618719/firestore-are-ids-unique-in-the-collection-or-globally

[Gintasz]

I know its late but here is what I did

String randomId() {
    var _randomId = Firestore.instance.collection('').document().documentID;
    print(randomId());
    return _randomId;
}

Doesn't work on web at the present moment (cloud_firestore: 0.13.7), getting this error:
Function Firestore.collection() requires its first argument to be of type non-empty string, but it was: ""