Socket io emit message to client from express controller method

I know that usually you will have to app.js

create a socket server and pass that instance to your router, which in turn can pass it to controller methods. As shown here ( Socket.io emit from Express controllers )

However, I have a controller method that is supposed to give progress to any client that happens to be listening, but that method can be executed from many different routes and other controllers, and I really don't want to pass the link socket

around all these other parts of the application.

Is there a better way to do this?

I was thinking something like a helper module socketio

. The module app.js

transmits a link to io

which you can get later ...

app.js

var io = require('socket.io').listen(server);    
require('./helpers/socketio').set(io);

      

        
        
        
      

    

helpers / socketio.js

var io=null;

exports.set = function(socketio) {
   io=socketio;
}

exports.get = function() {
  return io;
}

      

        
        
        
      

    

Then when you need it in the application.

var io = require('./helpers/socketio').get();
io.emit('message', {a:1, b:2});

      

        
        
        
      

    

Is there a cleaner way to do this? Obviously it can return null, which you will need to check. It just doesn't feel right.