Maximum value from Firebase Firestore collection

Question

collection
        *
        Random_Id1
                *amount:100
                *name:John
        Random_Id2
                *amount:150
                *name:Matt
        Random_Id3
                *amount:65
                *name:Alice

I have a firestore collection that has different documents under it. these documents have data within them(name,age,amount, etc.). is there a way i can return the highest or Maximum amount in the collection? I'm implementing this in java(android). In the case of the above structure, the Maximum will be 150. Thank you in advance

Answer 1

You have to use a query that is defined via a combination of orderBy() and limit(), as follows:

CollectionReference collectionRef = db.collection("collection");
Query query = collectionRef.orderBy("amount", descending: true).limit(1);

See the docs here https://firebase.google.com/docs/firestore/query-data/queries and here https://firebase.google.com/docs/firestore/query-data/order-limit-data