GraphQL 将输入 arguments 传递给订阅

Question

I'm trying to pass an input argument like ID to a GQL subscription. I'm working with:

const { PubSub } =require ('apollo-server');

This is the apollo subscription reference page

Basically I'm trying with this easy subscription typedef:

 type Subscription{
  subscribe_device(id: String!): device}

And this is my subscription resolver:

Subscription:{
    subscribe_device:(parent, args, context, info) =>{
        console.log(args)
        subscribe: () => pubsub.asyncIterator('stream')
    }
}

Actually without input arguments it works pretty good but in that case it seems to have problems with the asyncIterator

Without input arguments:

Subscription:{
    subscribe_device:{
        subscribe: () => pubsub.asyncIterator('stream'),
    }
}

Someone know how to manage that issue? How is it possible to input some arguments in subscriptions? I need it to create dynamically different "stream"

Thank you very much for your help

Answer 1

I think what you are looking for is additional middleware (which is in the documentation ) where you can do stuff between getting something and returning something

In addition, if you want to use the withFilters functionality, you can do a general calculation for every possible scenario and filter the desired outcome for a variables input and check with the payload . For example only those who ask for a specific result will get notified of the changes over socket.

Answer 2

If you need to describe to channel based on arguments, you just use the args to create the channel name based on it. For example:

Subscription:{
  subscribeDevice: {
    subscribe: (_parent, args, _context, _info) => { 
      const { someId } = args;
      return pubsub.asyncIterator([`stream_${someId}`])
    }
  }
}

This approach is working for me using apollo-server@2.19.0 .