How to use a prisma graphql subscription in node app

Question

I am following this guide. I am trying to listen to a graphQL subscription in my node app. I am having a lot of trouble implementing that subscription. I have a tried a few different ways, listed below, none of them are working.

// converted to rxjs observables
from(PrismaClient.$subscribe.priority({
    mutation_in: "CREATED"
})).subscribe(
    (next) => {
        console.log("next", next);
    },
    () => {
        console.log("error");
    },
    () => {
        console.log("complete");
    }
);

---

// as promise
PrismaClient.$subscribe.priority({
    mutation_in: "CREATED"
}).then(
    (next) => {
        console.log("next", next);
    }
);

---

Both of these just return in the next:

{ next: [Function: next],
  return: [Function: return],
  throw: [Function: throw],
  '@@asyncIterator': [Function] }

I would expect it to return the priority that was created any time a new one is created. However, it only returns one time and immediately completes and returns that object i listed above.

I understand this has something to do with it returning back an Promise<AsyncIterator<...>>, but i am not sure how to solve this issue.

How do i create a prisma graphql subscription in a node app using the prisma-client? I would also, like to convert this to rxjs instead of using promises. I just prefer Observables.

Answer 1

Here's a suggestion with Promises and async/await:

const main = async () => {
  const subscription = await PrismaClient.$subscribe.priority({
    mutation_in: 'CREATED',
  })
  handleSubscription(subscription)
}

const handleSubscription = async (subscription) => {
  const result = await subscription.next()
  console.log('do stuff with', result.value)

  if (!result.done) {
    console.log('handle again')
    handleSubscription(subscription)
  }
  else {
    console.log('done')
  }
}

main().catch(e => console.error(e))