承诺 Mongoose Connect 时出现类型错误

Question

我尝试使用 bluebird 来 Promisify Mongoose connect，我需要减少我的回调，所以我使用了 bluebird.But 它给了我下面的错误。

var expect = require('chai').expect;
var mongoose = require('mongoose');

var jobModel = require('../models/job');

var Promise = require('bluebird');

function resetJobs() {
  return new Promise(function(resolve, reject) {
    mongoose.connection.collections['jobs'].drop(resolve, reject);
  });
};

function findJobs(query) {
  return Promise.cast(mongoose.model('Job').find({}).exec());
};

var connectDB = Promise.promisify(mongoose.connect,mongoose);
describe('get jobs', function() {
  it('Should not be empty since jobs are seeded', function(done) {
    connectDB('mongodb://localhost/jobfinder').then(function() {
      resetJobs()
        .then(jobModel.seedJobs)
        .then(findJobs).then(function(jobList) {
          expect(jobList.length).to.be.at.least(1);
          done();
        });
    });
  });
});

但这给了我一个错误

Unhandled rejection TypeError: Cannot read property 'connection' of undefined
at Mongoose.connect (F:\MyProjects\JobFinder\node_modules\mongoose\lib\index.js:232:18)
at tryCatcher (F:\MyProjects\JobFinder\node_modules\bluebird\js\release\util.js:11:23)
at ret (eval at <anonymous> (F:\MyProjects\JobFinder\node_modules\bluebird\js\release\promisify.js:184:12), <anonymous>:14:23)
at Context.<anonymous> (F:\MyProjects\JobFinder\test\jobs-data-spec.js:22:3)

我使用的包版本如下

"bluebird": "^3.1.1",
"express": "^4.13.4",
"mongoose": "^4.3.6"

Answer 1

我正在编写相同的教程。
Bluebird 将 3.0 中的 api 从 // 2.x Promise.promisify(fn, ctx); // 3.0 Promise.promisify(fn, {上下文: ctx});

我更改了调用，调用停止抛出错误。

Bluebird 的解释请看这里： http://bluebirdjs.com/docs/new-in-bluebird-3.html

希望对您有所帮助

Answer 2

我也在编写相同的教程，以下是我为解决该问题所做的工作。

npm uninstall bluebird
npm install --save bluebird@2.0

然后当你运行你的测试mocha你应该通过。

Answer 3

下面的代码似乎对我有用。

var connectMongoose = Promise.promisify(mongoose.connect, {context: mongoose}); 
connectMongoose('MONGO_URL', mongoose)
 .then(..)

Answer 4

您也可以手动承诺 mongoose.connect，而不使用 bluebird：

const mongoose = require('mongoose');
const { promisify } = require('util');


const connectMongoose = promisify((resolve, reject) => {
    const options = { useNewUrlParser: true, useUnifiedTopology: true };
    const uri = 'mongodb+srv://<USERNAME>:<PASSWORD>' +
        '@cluster0.iz4o8.mongodb.net/<DB-NAME>?retryWrites=true&w=majority';
    try {
        mongoose.connect(uri, options, resolve);
    } catch (err) {
        reject(err);
    }
});


(async () => {
    try {
        await connectMongoose();
        console.log('connected to monoose! :)');
    }
    catch (err) {
        console.error('could not connect to mongoose :(', err);
        process.exit(-1);
    }
})();

承诺 Mongoose Connect 时出现类型错误

Type Error in Promisifying Mongoose Connect

mocha.js

mongoose

node.js

chai

bluebird