在Node.js中使用Exports从函数中的函数返回值 [英] Using exports in nodejs to return a value from function in a function

问题描述

我一直在阅读有关模块化代码的内容，并决定将一些函数导出到单独的文件中，并在调用它们后将其包含在我的主函数中.如果我调用它，只有我的网站配置不会返回:

I've been doing some reading on modularizing my code and decided to export some functions to a separate file and include them in my main function once it's called. Only my config of my website is not returning if I'm calling it:

// Export from my controller
// File: Controller.js
exports.site_config = function(company, data) {

   siteConfig.find({"company" : company}, function data (err, siteConfig, data) {
    // Console.log(siteConfig[0]) // Works
    return siteConfig[0] // This return is not working
    })
  // Only here returns works....
}

// File: Index.js
const siteController = require('../controllers/site');
console.log(siteController.site_config('company2')) // nothing return

推荐答案

这是

This is a special case of this problem. Synchronous code can be transformed to asynchronous but not vice versa.

Mongoose长期以来一直支持promises，回调API是旧的.这是他们的用例.

Mongoose has been supporting promises for a long time, callback API is legacy. This is a use case for them.

模块应导出配置对象的Promise.检索单个文档的更简洁方法是findOne:

A module should export a promise of configuration object. A more concise way to retrieve a single document is findOne:

exports.site_config = function(company, data) {
   return siteConfig.findOne({"company" : company});
};

并被当作诺言消费.应该有一个promise链，如果需要，可以到应用程序入口点:

And is consumed as a promise. There should be promise chain, up to to application entry point if needed:

// inside `async` function:
const siteController = require('../controllers/site');
const config = await siteController.site_config('company2');

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