Mongodb节点驱动程序2.0.*与Bluebird 2.9.*承诺

您可以在需要后直接承诺，如bluebird API文档中所示：

var Promise = require("bluebird");
var MongoDB = Promise.promisifyAll(require("mongodb"));
var util = require('util');
console.log(util.inspect(MongoDB, { showHidden: true }));

使用bluebird 2.9.14和mongodb驱动程序2.0.22，我得到了以下（简化）结果：

  // ....
  Collection: 
   { [Function]
     [length]: 6,
     [name]: '',
     [arguments]: [Getter/Setter],
     [caller]: [Getter/Setter],
     [prototype]: 
      { [constructor]: [Circular],
        collectionName: [Getter],
        // .... 
        findAsync: [Object],
        insertOneAsync: [Object],
        insertManyAsync: [Object],
        bulkWriteAsync: [Object],
        insertAsync: [Object],
        updateOneAsync: [Object],
        replaceOneAsync: [Object],
        updateManyAsync: [Object],
        updateAsync: [Object],
        deleteOneAsync: [Object],
        removeOneAsync: [Object],
        deleteManyAsync: [Object],
        removeManyAsync: [Object],
        removeAsync: [Object],
        saveAsync: [Object],
        findOneAsync: [Object],
        // ....

并像这样成功查询：

MongoDB.connectAsync('mongodb://localhost:27017/test').then(function(db) {
    return db.collection("orders").findOneAsync({});
}).then(function(orders) {
    console.log(orders);
}).catch(function(err) {
    console.log(err);
});

更新

使用MongoClient对象同样有效：

var Promise = require("bluebird");
var MongoDB = Promise.promisifyAll(require("mongodb"));
var MongoClient = Promise.promisifyAll(MongoDB.MongoClient);
MongoClient.connectAsync('mongodb://localhost:27017/test').then(function(db) {
    return db.collection("orders").find({}).toArrayAsync();
}).then(function(orders) {
    console.log(orders)
}).catch(function(err) {
    console.log(err);
});

默认情况下，如果不指定回调，mongodb驱动程序总是返回promise。但是，您可以使用首选的promise库指示它返回promise。

以下是使用nodemongodb原生2.0驱动程序时使用bluebird-promise的一个简单方法：

var Promise = require("bluebird");
var MongoClient = require("mongodb").MongoClient; // Doesn't require promisification
/*...*/
function saveData(data) {
  MongoClient
    .connect(MONGO_CONNECTION_STRING, {
      promiseLibrary: Promise // Here you instruct to use bluebird
    })
    .then(function(db) {
      return db
        .collection('myCollection')
        .insert(data)
        .finally(db.close.bind(db))
    })
    .catch(function(err) {
      console.error("ERROR", err);
    });
}

简化且更逼真的版本：

var Promise = require('bluebird');
var MongoDB = Promise.promisifyAll(require('mongodb'));
MongoDB.MongoClient.connectAsync('mongodb://localhost:27017/test')
  .then(function(db) { // Expose db to query logic
    // need to return a promise to let outer catch handle it
    return db.collection("orders").find({}).toArrayAsync()
      .then(function (orders) {
        console.log(orders);
      })
      // Ensure that db is closed at the end no matter what...
      .finally(db.close.bind(db)); 
      // No need for another catch here, the outer one will handle it 
  })
  .catch(console.log.bind(console));

Promise嵌套是故意将数据库暴露给其他逻辑的。通过全局传递或声明"db"，可以在不嵌套的情况下完成同样的操作。尝试了所有的，这一个是最优雅的。

您可以阅读MongoDB Native Driver:的来源

MongoClient.connect = function(url, options, callback) {
  var args = Array.prototype.slice.call(arguments, 1);
  callback = typeof args[args.length - 1] == 'function' ? args.pop() : null;
  options = args.length ? args.shift() : null;
  options = options || {};
  // Get the promiseLibrary
  var promiseLibrary = options.promiseLibrary;
  // No promise library selected fall back
  if(!promiseLibrary) {
    promiseLibrary = typeof global.Promise == 'function' ?
      global.Promise : require('es6-promise').Promise;
  }
  // Return a promise
  if(typeof callback != 'function') {
    return new promiseLibrary(function(resolve, reject) {
      connect(url, options, function(err, db) {
        if(err) return reject(err);
        resolve(db);
      });
    });
  }
  // Fallback to callback based connect
  connect(url, options, callback);
}

promiseLibrary可以设置Bluebird