# Interface GraphQLSubscription.Handler<T>

Enclosing class:
  `GraphQLSubscription`

public static interface GraphQLSubscription.Handler<T>
Receives the events of one subscription. All methods run on the Codename One EDT.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `onComplete()`
  The subscription ended cleanly (server `complete`, or a caller `GraphQLSubscription.cancel()`).
  `void`
  `onError(GraphQLResponse<T> response)`
  The subscription failed (an `error` message, a transport error, or a non-clean close).
  `void`
  `onNext(GraphQLResponse<T> response)`
  A `next` payload arrived and its `data` mapped to `T`.

- ## Method Details

  - ### onNext

    void onNext(GraphQLResponse<T> response)
    A `next` payload arrived and its `data` mapped to `T`. When the payload also carried `errors`, `response.hasErrors()` is true and `response.getData()` may still be non-null.

  - ### onError

    void onError(GraphQLResponse<T> response)
    The subscription failed (an `error` message, a transport error, or a non-clean close). No further events follow.

  - ### onComplete

    void onComplete()
    The subscription ended cleanly (server `complete`, or a caller `GraphQLSubscription.cancel()`). No further events follow.