Promise和Nodejs MongoDB驱动程序

手动散布API是很危险的，我建议采取以下措施：

TaskBroker.prototype._connectMongo = Q.nfcall(MongoClient.connect, 'mongodb://127.0.0.1:27017/test',{});TaskBroker.prototype.connectMongo = function(){   return this._connectMongo().then(function(db){       console.log("Hello");       // self.stuff...       return 42;   }).catch(function(e){       console.err("connection error",e); // log the connection error, or handler err       throw e; // don't mark as handled, propagate the error.   });};

有了Bluebird的承诺，它看起来就像：

var MongoClient = Promise.promisifyAll(require("mongodb").MongoClient);TaskBroker.prototype.connectMongo = function(){    return MongoClient.connectAsync().then(...         // Bluebird will automatically track unhandled errors        };