Query Firebase using Map value, Flutter

Question

I'm trying to query to my Firebase collection using the value inside of Array. I'm using arrayContains and then passing the value like shown in the code, but after querying, it returns a length of 0.

FirebaseFirestore.instance
.collection('chatrooms')
.where('users.0', arrayContains: {'studentid':'1WINXTQdshhn4jLfhMWWaZNNdL32'})
.get();

Here's an image of my database.

Database Collection

Answer 1

This cannot be done using array-contains . You must use the entire student object to query using array-containing . This query tries to find {'studentid':'1WINXTQdshhn4jLfhMWWaZNNdL32'} object inside the array of users.0 field. Read more about this here https://firebase.google.com/docs/firestore/query-data/queries#array_membership .