Work around for property 'Symbol(Symbol.toPrimitive)' in Proxy handler

[ChuanyuWang]

When I am trying to migrate to higher version nodeJS, e.g. 6.9.1. I found below error coming from Proxy handler, which is caused by Symbol property. So I add another workaround to skip Symbol property during Proxy's get handler

TypeError: '[object Object]' returned for property 'Symbol(Symbol.toPrimitive)' of object '[object Object]' is not a function
    at exports.format (util.js:108:18)
    at Console.log (console.js:43:37)
    at Database.<anonymous> (C:\git\test\app2.js:33:13)
    at emitNone (events.js:86:13)
    at Database.emit (events.js:185:7)
    at C:\git\test\node_modules\mongojs\lib\database.js:35:14
    at connectCallback (C:\git\test\node_modules\mongodb\lib\mongo_client.js:426:5)
    at C:\git\test\node_modules\mongodb\lib\mongo_client.js:364:13
    at _combinedTickCallback (internal/process/next_tick.js:67:7)
    at process._tickCallback (internal/process/next_tick.js:98:9)

Fix parsing database name from native driver to pass all test

[ChuanyuWang]

@saintedlama I am fan of mongojs, and it's the best nodejs API wrapper I used. As there are five open pull request to mongoja, may you help merge them and publish a new version?

[saintedlama]

I'm using node 8 and did not have any issue with Symbols at all. Could you explain to me why this PR is important and what it fixes?

[ChuanyuWang]

Glad to see you reply. Here is the sample code to reproduce this issue.

var mongojs = require('mongojs');
var db = mongojs(uriString);
console.log("" + db.toString()); // Good
console.log("" + db); // TypeError: '[object Object]' returned for property 'Symbol(Symbol.toPrimitive)' of object '[object Object]' is not a function

Testing on Window 10 64bit:

• node@6.9.1
• mongodb@3.2.5

The Symbol.toPrimitive is used to convert db object to primitive value, but it's treated as a collection name in file index.js line 15

var Database = require('./lib/database')
var mongodb = require('mongodb')

module.exports = function (connString, cols, options) {
  var db = new Database(connString, cols, options)
  if (typeof Proxy !== 'undefined') {
    var handler = {
      get: function (obj, prop) {
        // Work around for event emitters to work together with harmony proxy
        if (prop === 'on' || prop === 'emit') {
          return db[prop].bind(db)
        }

        if (db[prop]) return db[prop]
        db[prop] = db.collection(prop) // <== prop is actually a system level Symbol
        return db[prop]
      }
    }

    return Proxy.create === undefined ? new Proxy({}, handler) : Proxy.create(handler)
  }

  return db
}