How to use FieldValue.increment() on the property of an object type document field

Question

Firestore's FieldValue.increment(someValue) is working properly with other fields but not with map.

I am trying to increment the value of a property in a map. I have a document named user. It has a map points:{id:123, total:100}. I want to update the value of total in map points.

firestore.collection('users').doc('user').update({
    "name": "atul",
    "points": { "total": firestore.FieldValue.increment(50) }
})

Instead of incrementing the total value to 150, its value becomes 100.

Answer 1

You'll need to call out the full path of the field to increment, not bury it inside an object. The full path of the field involves using . as a separator between the names of each field:

firestore.doc(...).update({
    "points.total": firestore.FieldValue.increment(50)
})