Custom subscription when not using yoga as a server

[santino]

Hello folks, as mentioned by the title, I am looking to setup subscriptions in my Yoga implementation.
I am not using Yoga as a full server, but instead I am integrating it with my fastify instance.

The useGraphQLSSE plugin only seems to work if Yoga is executed as a server.
Do you have any example for writing up a plugin that only handles subscription requests received on my single /graphql endpoint?

[santino]

Currently, this is what I ended up implementing.

export const useSubscription = () => {
  return {
    async onSubscribe () {
      return {
        onSubscribeResult: async ({ result, args: { contextValue: { req, reply } } }) => {
          req.socket.on('end', () => {
            result.return()
            reply.hijack()
          })
          req.socket.on('close', () => {
            reply.log.info(
              {
                res: reply,
                responseTime: reply.elapsedTime
              },
              'request completed'
            )
            reply.raw.end()
          })

          for await (const data of result) {
            reply.raw.write(
              `event: next${EOL}data: ${JSON.stringify(data)}${EOL}${EOL}`
            )
          }
        }
      }
    }
  }
}

Let me know if you can think of any improvement

[santino]

Discard this.
Yoga supports subscriptions out of the box, even when used with other servers, like Fastify (which is what I am using).

I had a faulty setup to deliver an initial subscription value, which led me to think there was an issue with Yoga handling subscriptions.

Thanks to @ardatan's comment I ended up digging more and finding the proper way to handle this; as discussed in #3276