Subscriptions

Graphql-js expects subscription fields to return an AsyncIterable. Grats enforces this pattern by requiring that subscription fields return an AsyncIterable<T>. Beyond that, there is nothing special about subscriptions in Grats.

Example

TypeScript

import { Int } from "grats";

/** @gqlSubscriptionField */
export async function* countdown(): AsyncIterable<Int> {
  for (let i = 10; i >= 0; i--) {
    await sleep(1);
    yield i;
  }
}

function sleep(s: number) {
  return new Promise((resolve) => setTimeout(resolve, s * 1000));
}

Playground

GraphQL

type Subscription {
  countdown: Int
}

Working Example

See our Yoga Example Project for a working example of subscriptions in Grats.