Firestore-从添加的对象获取自动生成的ID

Question

I was not able to find a solution for that problem. All I do is inserting a custom object to my Firestore database. After the data is successfully inserted, I would like to get the id of the inserted object. Is that possible?

var group : Group = Group("test")
         firestore.collection("groups").add(group).addOnCompleteListener(OnCompleteListener {

         //get id 
    })

Answer 1

Yep. It'll be something like

OnCompleteListener { val id = it.result.id }

Basically, the on complete method (you'll want to check if its successful in here btw) should give you a document object in the callback which you can get the id from!

Answer 2

If you want to get the id of document while adding it to the database, please use the following code:

val rootRef = FirebaseFirestore.getInstance()
val groupsRef = rootRef.collection("groups")
val group = Group("test")
val id = groupsRef.document().id //Get the document id
groupsRef.document(id).set(group).addOnSuccessListener {
    Log.d("TAG", "The document with " + id + " was successfully added!")
}