[英]Node.js: Converting module functions from callbacks to promises with Bluebird
I have a simple module with a couple of functions to interact with an Active Directory. 我有一个简单的模块,其中包含几个与Active Directory进行交互的功能。
Using the standard callback style, the code works just fine: 使用标准的回调样式,代码可以正常工作:
/**
* mylib.js
**/
const ActiveDirectory = require('activedirectory');
// Instantiate AD client
const ad = new ActiveDirectory({
url: 'ldaps://...',
baseDN: 'DC=...',
});
module.exports = {
// Authenticate user against the AD
authenticate: (username, password, callback) => {
// Authentication request
ad.authenticate(username, password, (err, status) => {
callback(err, status);
});
},
};
/**
* client.js
**/
const mylib = require('./mylib');
mylib.authenticate('<username>', '<password>', (err, status) => {
if (err) {
console.log(`Error: ${err}`);
return;
}
console.log(`Success: ${status}`);
});
Execution result: 执行结果:
> node client.js
Success: true
The next step was to refactor my lib method to use Promises instead of callbacks: 下一步是重构我的lib方法以使用Promises而不是回调:
/**
* mylib.js
**/
const ActiveDirectory = require('activedirectory');
const Promise = require('bluebird');
//...
module.exports = {
// Authenticate user against AD
authenticate: Promise.method((username, password) => {
ad.authenticate(username, password, (err, status) => {
if (err) throw err;
return status;
});
}),
};
/**
* client.js
**/
const mylib = require('./mylib');
myLib.authenticate('<username>', '<password>').then((status) => {
console.log(`Success: ${status}`);
}).catch((err) => {
console.log(`Error: ${err}`);
});
Execution result: 执行结果:
> node client.js
Success: undefined
So it looks like the status
is not being resolved. 因此,看起来
status
尚未解决。
If I change the AD server URL to something else (to force a connection error and see the rejection) I can see both the resolve and the rejection log: 如果我将AD服务器URL更改为其他名称(以强制执行连接错误并查看拒绝),则可以同时看到解析和拒绝日志:
> node client.js
Success: undefined
/Users/.../mylib.js:84
if (err) throw err;
^
Error: connect ECONNREFUSED <IP>
at Object.exports._errnoException (util.js:1036:11)
at exports._exceptionWithHostPort (util.js:1059:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1080:14)
What am I doing wrong? 我究竟做错了什么? Can't figure it out.
无法解决。
You are expecting too much of Promise.method()
, from which a thrown error or returned value will indeed be promise wrapped, but that's not what you are doing - you are throwing/returning from ad.authenticate's callback. 您对
Promise.method()
的Promise.method()
过高,确实会从中包装抛出的错误或返回值,但这并不是您正在做的事情-您正在从ad.authenticate的回调中抛出/返回。
What you want is a promisified version of ad.authenticate
, which Bluebird makes extremely simple. 你想要的是一个promisified版本
ad.authenticate
,这使得青鸟非常简单。
module.exports = {
// Authenticate user against AD
authenticate: Promise.promisify(ad.authenticate)
};
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