Watch

Watch operation allows monitoring for changes in a single collection. The change stream can be created by calling watch method on a MongoCollection[F, T] instance, which can also optionally take an aggregation pipeline as an argument. Once created, the change stream will start emitting change event documents whenever changes are being produced.

import mongo4cats.bson.Document

val changes: fs2.Stream[IO, Document] = collection.watch.stream

// or with an aggregation pipeline included
import mongo4cats.collection.operations.{Aggregate, Filter}

val changes: fs2.Stream[IO, Document] = collection.watch(Aggregate.matchBy(Filter.gte("amount", 100))).stream