Issue
I want to add new key to a map. memberFees is a field of a document under collection named Faculty
I want to store only the key of each member fee inside the memberFees map.
Here is an example of my memberFees map:
I only added that keys in the example manually.
This is what I did:
writeBatches.get(batchIndex).update(db.collection("Faculty")
.document(faculty.getId()), "memberFees/" + memberFeeId, true);
This code throws an error:
java.lang.IllegalArgumentException: Invalid document reference. Document references must have an even number of segments, but Faculty/7DEj7mlTPBf3cVSCtQO3/memberFees has 3
at com.google.firebase.firestore.DocumentReference.forPath(DocumentReference.java:81)
Solution
When updating a nested field, use .
to separate the field names. Your code uses /
, which Firestore interprets as a subcollection.
So:
writeBatches.get(batchIndex).update(db.collection("Faculty")
.document(faculty.getId()), "memberFees." + memberFeeId, true)
// 👆
Answered By – Frank van Puffelen
Answer Checked By – Robin (FlutterFixes Admin)