Firestore: Invalid document reference. Document references must have an even number of segments,

Issue

I have a futter app and want to add items favorite by the user in a separate collection "userFavorites" which will store all favorite items depending on the current user uid by doing so:

Future getCurrentUser() async {
    final FirebaseUser user = await FirebaseAuth.instance.currentUser();
    final uid = user.uid;
    return uid.toString();
    }

    Future<void> toggleFavoriteStatus() async{

    var userId = await getCurrentUser();

    final oldStatus = isFavorite;
    isFavorite = !isFavorite;
    notifyListeners();
    try{
     await Firestore.instance.collection("userFavorites/$userId").document(id).updateData({
           'isFavorite': isFavorite,
         });
    }catch(error){
      _setFavValue(oldStatus);
     }
}

But I receive this error when I try to favorite any item:

Invalid document reference. Document references must have an even number of segments, but userFavorites/FRbYxmNpSBcda6XOrQUjukvFvVb2/q7eLxtZfhG3g6Pd1bYY4 has 3
E/MethodChannel#plugins.flutter.io/cloud_firestore(14551):  at com.google.firebase.firestore.DocumentReference.forPath(com.google.firebase:firebase-firestore@@21.3.0:80)

Solution

The error message:

Invalid document reference. Document references must have an even number of segments, but userFavorites/FRbYxmNpSBcda6XOrQUjukvFvVb2/q7eLxtZfhG3g6Pd1bYY4 has 3

is telling you that you built a path to a document:

userFavorites/FRbYxmNpSBcda6XOrQUjukvFvVb2/q7eLxtZfhG3g6Pd1bYY4

which doesn't look like a document at all, since it has three path segments:

1. userFavorites
2. FRbYxmNpSBcda6XOrQUjukvFvVb2
3. q7eLxtZfhG3g6Pd1bYY4

This is the line of code that built your path:

Firestore.instance.collection("userFavorites/$userId").document(id)

Since we can't see your data, it's hard to tell what you actually meant to do here. But in any event, Firestore is taking "userFavorites" to be the name of a top level collection, "FRbYxmNpSBcda6XOrQUjukvFvVb2" is the name of a document in that collection, and "q7eLxtZfhG3g6Pd1bYY4" is taken to mean a subcollection under that document. If you meant something else, you'll have to figure out how to build the path to that document to query it.

Answered By - Doug Stevenson