subscribeBackground

There are certain situations in which you may want to subscribe to a query from the server without immediately needing the results. subscribeBackground cuts down on some of the work that subscribe does, by setting up a connection for a given query but not materializing the results for a callback function. The data will still be synced to the local database and accessible via other subscriptions.

subscribeBackground can support a pattern where you have one large subscription to keep your local database up to date, and then define many local-only subscriptions that you know to be a subset of the larger subscription. This will cut down on traffic to the server and in some cases improve performance. However, it may also lead to more data being synced than is necessary.

const unsubscribeBackground = client.subscribeBackground(
  query,
  // Optional
  {
    onFulfilled: () => {
      console.log(
        'server has inserted initial results for the subscription into the local database'
      );
    },
    onError: (error) => {
      console.error('error in background subscription', error);
    },
  }
);