Subscription

The Subscription allows you to subscribe to server-side events with Buoy. A little setup is required before use. The Subscription returns an Observable (opens new window).

Initializing a new Subscription

A WatchQuery is initialized through the Buoy-service.

export class AppComponent implements OnDestroy {

    public mySubscription: Subscription;

    constructor(
        private buoy: Buoy
    ) {
        this.myMovieSubscription = this.buoy.subscribe(
            // Query
            gql `
                subscription ($id: Int!) {
                    movieUpdated(id: $id) {
                        title
                        poster
                    }
                }
            `,
            // Variables
            {
                id: 1
            },
            // Options
            {
                scope: 'movieUpdated',
                onChange: (id, data) => {
                    console.log(`Operation ${id} received a new event:`, data);
                }
            }
        );
    }
}

The buoy.subscribe-method returns an Observable (opens new window). However, it is also possible to simply add a callback with the onChange-option. This method won't require you to manually unsubscribe from the Observable.

Handling events from Buoy

TODO

Options

Options are added as the third parameter on the buoy.subscribe()-method.

scope TODO change to subscription-response

The scope will change the root of the data returned by the GraphQL-server.

The server will often return something like this:

{
    "movies": {
        "data": [
            { "title": "Movie 1" },
            { "title": "Movie 2" }
        ]
    }
}

With the scope movies.data, you can skip the two first levels, and receive:

[
    { "title": "Movie 1" },
    { "title": "Movie 2" }
]

The scope should generally be the name of the first node in your query followed by .data, if your node is a paginator.

Methods

unsubscribe TODO

This method will unsubscribe you from further events from the GraphQL-server.

Callbacks

The callbacks are also added as options on a Subscription.

onInitialized

Is fired once the Subscription has been initialized.

Parameters

Parameter	Type	Explanation
id	number	Buoy operation ID

onChange

Is fired when a new event is received from the server.

Parameters

Parameter	Type	Explanation
id	number	Buoy operation ID
data	any	Scoped data.