javascript node.js 中的类方法
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/11782453/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Class methods in node.js
提问by Patrick
I've been trying for the last hour to write a user module for passport.js with the findOne, findOneOrCreate, etc. methods, but can't get it right.
在过去的一个小时里，我一直在尝试使用 findOne、findOneOrCreate 等方法为passport.js 编写用户模块，但无法正确完成。
User.js
用户.js
var User = function(db) {
this.db = db;
}
User.prototype.findOne(email, password, fn) {
// some code here
}
module.exports = exports = User;
app.js
应用程序.js
User = require('./lib/User')(db);
User.findOne(email, pw, callback);
I've been through dozens of errors, mostly
我经历了几十个错误，主要是
TypeError: object is not a function
or
或者
TypeError: Object function () {
function User(db) {
console.log(db);
}
} has no method 'findOne'
How do I create a proper module with these functions without creating an object/instance of User?
如何在不创建用户对象/实例的情况下使用这些函数创建适当的模块？
Update
更新
I went over the proposed solutions:
我回顾了建议的解决方案：
var db;
function User(db) {
this.db = db;
}
User.prototype.init = function(db) {
return new User(db);
}
User.prototype.findOne = function(profile, fn) {}
module.exports = User;
No luck.
没有运气。
TypeError: Object function User(db) {
this.db = db;
} has no method 'init'
回答by Dominic Barnes
A couple of things are going on here, I've corrected your source code and added comments to explain along the way:
这里发生了一些事情，我已经更正了您的源代码并添加了注释以在此过程中进行解释：
lib/User.js
库/用户.js
// much more concise declaration
function User(db) {
this.db = db;
}
// You need to assign a new function here
User.prototype.findOne = function (email, password, fn) {
// some code here
}
// no need to overwrite `exports` ... since you're replacing `module.exports` itself
module.exports = User;
app.js
应用程序.js
// don't forget `var`
// also don't call the require as a function, it's the class "declaration" you use to create new instances
var User = require('./lib/User');
// create a new instance of the user "class"
var user = new User(db);
// call findOne as an instance method
user.findOne(email, pw, callback);
回答by 3on
You need to new User(db)at some point.
你需要new User(db)在某个时候。
You could make an init method
你可以做一个 init 方法
exports.init = function(db){
return new User(db)
}
And then from your code:
然后从你的代码：
var User = require(...).init(db);
