websockets_server.js obsolite?

[sysgears]

websockets_server.js obsolite?

[larixer]

No, it is not obsolete. The subscriptions will stop working if you delete it.

[mitjade]

Opened 2 browsers and tried it out. Still working..

[larixer]

@mitjade Yes you are right, actually subscriptions server is set up in api_server.js, so I think websockets_server.js is outdated indeed.

[mitjade]

Found this out by accident. Will create PR.

Am trying to add mqtt client so I would be able to publish mqtt events in mutations and still keep existing subscriptions, but can not seem to set it in a way to not have it restart on page reload or hot code reload, but still be able to expose client publish in schema.

I know this has nothing to do with this starter kit, but if you have any short pointers on how to archive this, would really appreciate it. If not np.

[larixer]

@mitjade I have no idea. If you could show me the code, that reveals the problem with hot code reload, I might be able to look when I will have time. I believe even making subscriptions in this starter kit to hot reload code changes in counter mutation code without restarting subscriptions might not be possible. Generally subscriptions need to be made hot code reload friendly first.

[mitjade]

Thx. Will prepare something in a fork, if I will not be able to figure this out.

[mitjade]

https://github.com/mitjade/apollo-fullstack-starter-kit/commit/cc3e95e70b8ae4c9693fb117900f602278ee8026

Here is an example of what I'm trying accomplish.

Start an MQTT client and subscribe to specific topics, which I managed to get working.

What I am not able to do, is to export a publish function in src/server/api/mqtt_client.js that I could then call when a certain Mutation is triggered.

If I call it as demonstrated in src/server/api/schema.js, if you press the 'Click to increase count', I get an:
error { TypeError: _mqtt_client2.default.publish is not a function

I tried a few different approaches, all unsuccessful, so it looks like I still need to learn a few things on how javascript works...

[mitjade]

Another approach was:

src/server/api/schema.js

...
  Mutation: {
    addCount(_, { amount }, context) {
      const client = mqttClient();
      client.publish('topic', 'message');

Here I get:
error { TypeError: Cannot read property 'on' of undefined

[larixer]

Yes, you are certainly doing something wrong, why your src/server/api/mqtt_client.js closure has parameter mqttClient, e.g. export default (mqttClient) =>, where do you pass this parameter to your closure? You don't pass it at all

[larixer]

You should call your mqtt_client.js module like this:
mqttClient(realMqttClientInstance).publish('topic', 'message');

[mitjade]

How do I export the mqttClient instance from the src/server/api_server.js so I can access it in src/server/api/schema.js?

[mitjade]

export default mqttClient; in the src/server/api_server.js.

Sorry for a stupid question :) will try it out now.

[larixer]

I believe the way to do it is to use Apollo GraphQL context, see file middleware/graphql.js you should pass an instance of your mqttClient as parameter there, e.g.

app.use('/graphql', (...args) => graphqlMiddleware(mqttClient)(...args));

export default mqttClient => graphqlExpress(() => {
  return {
    schema,
    context: {
      Count: new Count(),
      mqttClient: mqttClient
    },
  };
});

And then in your GraphQL schema you will be able to access mqttClient from context, the same way new Count() instance is accessed from context

[mitjade]

Managed to get it working!

Thank you AGAIN for the help!!! I would probably keep banging my head agains the wall with this problem for quite a while. I guess I need to read up on some javascript fundamentals :)