Google Firestore: Query on substring of a property value (text search)

Question

I am looking to add a simple search field, would like to use something like

collectionRef.where(\'name\', \'contains\', \'searchTerm\')

I tried

Answer 1

Late answer but for anyone who's still looking for an answer, Let's say we have a collection of users and in each document of the collection we have a "username" field, so if want to find a document where the username starts with "al" we can do something like

 FirebaseFirestore.getInstance().collection("users").whereGreaterThanOrEqualTo("username", "al")