Question

I am using the async library (https://github.com/caolan/async)
on node trying to execute multiple db queries async with mongoskin (https://github.com/guileen/node-mongoskin)

The problem is when using the map function like so

app.post '/events', (req, res) ->
  storage.events.getByUser req.session.authId, (events) ->
    async.map events, storage.codes.getCountByEvent, (err, results) ->
      res.send results

it is binding @ to the global namespace on the getCountByEvent function, does anybody with experience with the async library able to give me guidance on the best way to fix this?

Here is the sample of the storage.codes implementation

class Codes
    constructor: (db) ->
        db.bind 'codes',
            getCountByEvent: (event, callback) ->
                @.find(event: event._id).toArray (err, res) ->
                    callback res.length

        return db.codes

exports.Codes = Codes

calling getCountByEvent outside of the async.map it will work fine

Thanks in advance

Answer 1

You could create a version of getCountByEvent that’s bound to the storage.codes object:

async.map events, storage.codes.getCountByEvent.bind(storage.codes), ...