Mongodb节点驱动程序2.0.*与Bluebird 2.9.*promisification

Question

因此,围绕此主题还有一些其他查询,例如: 如何使用bluebird宣传MongoDB本机Javascript驱动程序？

但它似乎没有解决最新版本的驱动程序,这似乎在尝试promisify时有问题.目前我可以通过以下方式MongoClient开展工作:

Promise.promisifyAll(mongodb.MongoClient); // Using .Prototype here fails to promisify

然而,无论我尝试什么收集似乎没有使用*async调用操作,它可能会调用它们,但它们永远不会被解决或拒绝,所以他们只是陷入困境.

历史上在以前的版本中你只会Promise.promisifyAll(mongodb)和你完成,但我不确定如何在新的驱动程序中正确处理它.

以下是使用mongo direct promisification创建的集合的示例输出,connectAsync然后从返回的db中获取集合.一旦我尝试对集合做任何事情,它就会挂起并承诺不会从它返回:

{ s: { pkFactory: { [Function: ObjectID] index: 14727641, createPk: [Function: createPk], createFromTime: [Function: createFromTime], createFromHexString: [Function: createFromHexString], isValid: [Function: isValid], ObjectID: [Circular], ObjectId: [Circular], createPkAsync: [Object], createFromTimeAsync: [Object], createFromHexStringAsync: [Object], isValidAsync: [Object], bindAsync: [Object], toStringAsync: [Object], callAsync: [Object], applyAsync: [Object], lazyAsync: [Object], throttleAsync: [Object], debounceAsync: [Object], delayAsync: [Object], everyAsync: [Object], cancelAsync: [Object], afterAsync: [Object], onceAsync: [Object], fillAsync: [Object] }, db: { domain: [Object], _events: {}, _maxListeners: undefined, s: [Object], serverConfig: [Getter], bufferMaxEntries: [Getter], databaseName: [Getter], options: [Getter], native_parser: [Getter], slaveOk: [Getter], writeConcern: [Getter] }, topology: { domain: [Object], _events: [Object], _maxListeners: undefined, connectTimeoutMS: 500, s: [Object], bson: [Getter], isMasterDoc: [Getter], poolSize: [Getter], autoReconnect: [Getter], host: [Getter], port: [Getter], emitOpen: false, socketTimeoutMS: 0 }, dbName: 'some-db-name', options: {}, namespace: 'some-namespace', readPreference: null, raw: undefined, slaveOk: false, serializeFunctions: undefined, internalHint: null, collectionHint: null, name: 'some-collection-name' } }

Answer 1

您可以在要求之后直接进行宣传,如bluebird API文档中所示,如下所示:

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,我得到了这个(简化的)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],
        // ....

并成功查询如下:

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);
});

UPDATE

使用该MongoClient对象也可以:

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);
});

Answer 2

默认情况下,如果您未指定回调,则mongodb驱动程序始终返回承诺.但是你可以指示它使用你喜欢的promises库返回promises.

这是使用node-mongodb-native 2.0驱动程序时使用bluebird promises的简单方法:

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);
    });
}