异步方法链接? [英] Async Method Chaining?
本文介绍了异步方法链接?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试使用异步方法链接创建一个类.但是,在我从数据库中完全获取数据之前,我仍在设置新值.我想念什么吗?
I'm trying to create a class with async method chaining. However, I'm still setting the new values before I fully fetch the data from the database. Am I missing something?
我也不想使用任何第三方模块.
I also don't want to use any third-party modules.
/* Class */
class UserDB {
constructor() {
this.user = {}
this.user.username = null
}
set(name, value) {
this.user[name] = value
return this
}
update() {
return new Promise((resolve, reject) => {
const db = MongoConnection.client.db('database').collection('users')
db.updateOne({ _id: this.user._id }, { $set: this.user}, (err, result) => {
if (err) reject(err)
resolve(this)
})
})
}
findByEmail(email) {
return new Promise((resolve, reject) => {
const db = MongoConnection.client.db('database').collection('users')
db.findOne({ email: email }, (err, result) => {
if (err) reject(err)
this.user = result
resolve(this)
})
})
}
}
module.exports = UserDB
/*execution*/
new UserDB().findByEmail('email@email.com')
.set('username', 'new_name')
.update()
推荐答案
那确实很有趣.您可以使用将操作附加到 .then
链的方法来使返回的Promise重载:
Thats indeed interesting. You could overload the returned Promise with methods that attach the operation to a .then
chain:
class AsyncChainable {
constructor() {
this._methods = {};
const that = this;
for(const key of Object.getOwnPropertyNames(Object.getPrototypeOf(this))) {
this._methods[key] = function(...args) {
return that.chain(this.then(() => that[key](...args)));
}
}
chain(promise) { return Object.assign(promise, this._methods); }
}
然后在您的custon课堂中使用它:
Then use that in your custon class:
class User extends AsyncChainable {
login() {
return this.chain((async () => {
// some logic
})());
}
}
这样您就可以做到:
(new User).login().login().then(console.log);
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