node.js中的类方法 [英] Class methods in node.js

问题描述

我一直在尝试用findOne，findOneOrCreate等方法为passport.js写一个用户模块，但是无法正确的。

User.js

  var User = function（db）{
 this.db = db; 
} 
 
 User.prototype.findOne（email，password，fn）{
 //某些代码在这里
} 
 
模块。 exports = exports = User; 
  

app.js

 $ code User = require（'./ lib / User'）（db）; 
 User.findOne（email，pw，callback）; 
  

我经历了几十个错误，主要是

  TypeError：对象不是函数
  

或

  TypeError：Object function（）{
函数用户（db）{
 console.log ）; 
} 
}没有方法'findOne'
  

如何创建一个

更新

<我曾经提出过解决方案：

  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; 
  

没有运气。

  TypeError：Object function User（db）{
 this.db = db; 
}没有方法'init'
  

解决方案

有几件事情在这里，我已经纠正了你的源代码，并添加了评论来解释：

lib / User.js

  //更简洁的声明
函数用户（db）{
 this.db =分贝; 
} 
 
 //你需要在这里分配一个新的函数
 User.prototype.findOne = function（email，password，fn）{
 // some code这里
} 
 
 //不需要覆盖`export` ...因为你正在替换`module.exports`本身
 module.exports = User; 
  

app.js

  //不要忘记`var` 
 //也不要将require作为函数调用，它是用于创建新的类声明实例
 var User = require（'./ lib / User'）; 
 
 //创建一个新的用户实例class
 var user = new User（db）; 
 
 //调用findOne作为一个实例方法
 user.findOne（email，pw，callback）; 
  

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.

User.js

var User = function(db) {
  this.db = db;
}

User.prototype.findOne(email, password, fn) {
  // some code here
}

module.exports = exports = User;

app.js

User = require('./lib/User')(db);
User.findOne(email, pw, callback);

I've been through dozens of errors, mostly

TypeError: object is not a function

or

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?

Update

I went over the proposed solutions:

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.

TypeError: Object function User(db) {
  this.db = db;
} has no method 'init'

解决方案

A couple of things are going on here, I've corrected your source code and added comments to explain along the way:

lib/User.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

// 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);

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