[英]module.exports is not a function nodejs
Quoting only the important parts of the code. 仅引用代码的重要部分。 This is my
server.js
in the node backend server 这是我在节点后端服务器中的
server.js
//routes
const userapi = require('./api/routes/user');
//models
require('./api/models/userModel');
//use routes
userapi(app);
on my userapi
which is my routes I call my userController
在我的
userapi
,这是我的路线,我称我的userController
(function () {
'use strict';
module.exports = function (app) {
var userCtrl = require('../controllers/userCtrl');
app.post('/api/validate_user', function(req, res, next){
userCtrl.validate_user(req, res);
});
}
})();
and this is my userController code. 这是我的userController代码。 In the future, i will write a code that will handle all the transaction from my MongoDB.
将来,我将编写一个代码来处理MongoDB中的所有事务。
'use strict';
var mongoose = require('mongoose'),
model = mongoose.model('users'),
brcpyt = require('bcrypt');
module.exports = function() {
return {
validate_user: function(req, res) {
console.log('here');
}
}
};
The problem is, everytime I make a http request from my frontend. 问题是,每次我从前端发出http请求时。 I get an error that says
userCtrl.validate_user
is not a function. 我收到一条错误消息,指出
userCtrl.validate_user
不是一个函数。 My frontend can access the endpoints of '/api/validate_user'
and the var userCtrl = require('../controllers/userCtrl')
is a correct file path, but everytime that I type userCtrl
to my routes it does not give me function validate_user
我的前端可以访问
'/api/validate_user'
的终结点,并且var userCtrl = require('../controllers/userCtrl')
是正确的文件路径,但是每次我将userCtrl
到路由时,它都不会给我功能validate_user
require gives you the value assigned to module.exports, so your code is like: require给您分配给module.exports的值,因此您的代码如下:
var userCtrl = function() {
return {
validate_user: function(req, res) {
console.log('here');
}
}
};
userCtrl.validate_user(...);
Do you see the bug now? 您现在看到错误了吗? userCtrl is a function, and therefore doesn't have a validate_user property ...
userCtrl是一个函数,因此不具有validate_user属性。
You really don't need to be wrapping your modules in IIFEs. 您确实不需要将模块包装在IIFE中。 That said, the issue you are seeing specifically is because your userCtrl module is exporting a function that, when called, returns an object which will then have a
validate_user
member -- it's not exporting an object directly. 也就是说,您具体看到的问题是因为您的userCtrl模块正在导出一个函数,该函数在被调用时返回一个对象,该对象将具有
validate_user
成员-而不是直接导出对象。 Try checking the value of typeof userCtrl
- it'll be function
instead of an object
, which is what you're expecting here :) 尝试检查
typeof userCtrl
的值-它将是function
而不是object
,这是您期望的在这里:)
Specifically, the following should work with no changes to userCtrl: 具体来说,以下内容应在不更改userCtrl的情况下起作用:
var userCtrl = require('../controllers/userCtrl')()
Notice the extra parenthesis at the end? 注意最后的括号吗? That will invoke the exported function and give you back an object with a
validate_user
method. 这将调用导出的函数,并为您提供一个带有
validate_user
方法的对象。 This pattern is sometimes used when you'd like to pass some options to the module, like a factory pattern. 当您要将某些选项传递给模块时,有时会使用此模式,例如工厂模式。 For example,
例如,
const userCtrlFactory = require('../controllers/userCtrl') const userCtrl = userCtrlFactory({ option: value })
This, however, is not the best way to do so, you would be using classes for that. 但是,这不是最好的方法,您将为此使用类。
I recommend you drop the IIFEs from your code ( (function () {})()
) and just have a top-level module.exports
(like you did with the userCtrl) that exports either an object or a class, depending on what you need from it. 我建议您从代码(
(function () {})()
)中删除IIFE,并只使用一个顶层module.exports
(就像您对userCtrl所做的那样)会根据对象导出一个对象或一个类。您需要它。 For userCtrl, just export an object directly as you're not passing options or have a need for "instantiating" a controller more than once: 对于userCtrl,只需直接导出对象即可,因为您没有传递选项,或者需要多次“实例化”控制器:
'use strict'; module.exports = { validate_user: ... };
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