trait Observer[T] extends Subscriber[T]
A Scala based wrapper of the Subscriber interface which provides a mechanism for receiving push-based notifications.
Will receive a call to Observer.onSubscribe(subscription: Subscription) on subscription to the Observable.
Default implementations of this trait are greedy and will call Subscription.request with Long.MaxValue so that all results are
requested. Custom implementations of the onSubscribe method can be used to control "back-pressure" and ensure that only demand that
the Observer is capable of handling is requested.
After signaling demand:
- Zero or more invocations of Observer.onNext up to the maximum number defined by Subscription.request - Single invocation of Observer.onError or Observer.onComplete which signals a terminal state after which no further events will be sent.
- T
The type of element signaled.
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Abstract Value Members
- abstract def onComplete(): Unit
Notifies the Subscriber that the Observable has finished sending push-based notifications.
Notifies the Subscriber that the Observable has finished sending push-based notifications.
The Observable will not call this method if it calls onError.
- Definition Classes
- Observer → Subscriber
- abstract def onError(e: Throwable): Unit
Notifies the Observer that the Observable has experienced an error condition.
Notifies the Observer that the Observable has experienced an error condition.
If the Observable calls this method, it will not thereafter call onNext or onComplete.
- e
the exception encountered by the Observable
- Definition Classes
- Observer → Subscriber
- abstract def onNext(result: T): Unit
Provides the Observer with a new item to observe.
Provides the Observer with a new item to observe.
The Observer may call this method 0 or more times.
The Observable will not call this method again after it calls either onComplete or onError.
- result
the item emitted by the Observable
- Definition Classes
- Observer → Subscriber
Concrete Value Members
- def onSubscribe(subscription: reactivestreams.Subscription): Unit
Handles the automatic boxing of a Java subscription so it conforms to the interface.
Handles the automatic boxing of a Java subscription so it conforms to the interface.
- subscription
the Java subscription
- Definition Classes
- Observer → Subscriber
- Note
Users should not have to implement this method but rather use the Scala
Subscription.
- def onSubscribe(subscription: Subscription): Unit
Invoked on subscription to an Observable.
Invoked on subscription to an Observable.
No operation will happen until Subscription.request is invoked.
It is the responsibility of this Subscriber instance to call Subscription.request whenever more data is wanted.
- subscription
Subscription that allows requesting data via Subscription.request
This is the documentation for the MongoDB Scala driver.
Driver structure
The mongodb scala driver.
To get started you need a MongoClient instance, either from a connection string or via a org.mongodb.scala.MongoClientSettings.
Notable packages include: