变量没有从函数中获取返回值答案

【问题标题】：Variable not picking up returned value from function变量没有从函数中获取返回值
【发布时间】：2019-02-22 18:30:52
【问题描述】：

我正在尝试将 send-mail 和 sendms 这两个函数的返回值收集到一个变量（var ordermessage）中。它可以很好地从 send-sms 中获取返回值。

我正在使用 mailgun api 发送邮件，而 ordermessage 只是选择了“未定义”。但是发送邮件一直在运行。

我试过`await mailgun.messages().send(...)`
我试过`const myvar = await mailgun.messages().send(...)`
还有`let myvar = await mailgun.messages().send...`

纳达。

我尝试使用将 api 调用作为回调的函数。仍然未定义。电子邮件和短信都已发送，但我需要电子邮件服务器的回复。我正在使用 Mailgun 试用版，所以我需要回复。

发送邮件.js

var mailgun = require('mailgun-js')({apiKey: process.env.MAILGUN_API_KEY, domain: process.env.MAILGUN_DOMAIN});
  var processresponse = "\n";

  var data = {
    from: 'Zigy Demo Store <admin_demo@zigy.com>',
    to: email,
    subject: 'You have placed an order.',
    text: body
  };

  console.log("\n----------START EMAIL-------------\n");

mailgun.messages()
  .send(data, function (error, body) {
    console.log("\nFinally running MAILGUN. Return body is\n", body);
    if (body == undefined || body == false) { 
      console.log("Got nothing from server.");
    } else {
      processresponse += body.message;
      console.log("***********************Gotten reply from Mailgun server.*******************************\n", processresponse);
    }
  });

订单控制器功能

module.exports = {
    neworder: async function(req, res) {
        var sendemail = require('./send-mail');
        var sendtext = require('./send-sms');

        var orderdetails = 'New order created at '+ new Date() + '\nItem  ---> Price'; //Message that will be sent to users.
        var item;
        var printcart = await Shoppingcart.findOne({
            where: {
                id: req.body.cart,
                owner: req.body.user
            }
        }).populate('product');
        var ordermessage = '';

        for (items in printcart.product) {
            item = printcart.product[items];
            orderdetails += '\n' + item.name + ' ---> ' + item.price;
        }
        console.log(orderdetails);
        //to get email addr and phone number
        phone = req.body.phone; 
        var email = req.body.email;

        var user = await User.findOne({id:printcart.owner});

        ordermessage += await sendemail(email, orderdetails); 
        console.log("\nAfter email, the message is ", ordermessage);

        ordermessage += await sendtext(phone, orderdetails);
        console.log("\nAfter text, Printing order message to be returned to browser ", ordermessage);

        console.log("Final message ", ordermessage);

        res.send(ordermessage);
    }
};

终端

----------START EMAIL-------------

Calling test function

After email, the message is  


Finally running MAILGUN. Return body is
 { id:
   '<20190222062410.1.FD7A4868FA0ADF5E@sandbox612cf746219c46ad93d5dc588f9341ff.mailgun.org>',
  message: 'Queued. Thank you.' }
***********************Gotten reply from Mailgun server.*******************************

Queued. Thank you.
Checking list of verified numbers...
Found the phonenumber!
You will receive an SMS message with your order details soon.

After text, Printing order message to be returned to browser  
You will receive an SMS message with your order details soon.
Final message  
You will receive an SMS message with your order details soon.
SM9bc04208f9354834a153fb1ffd7dc8bb

任何帮助将不胜感激。

编辑：我改为从 send-mail.js 和 send-sms.js 内部调用 res.write，并去掉了变量 ordermessage。

【问题讨论】：

看起来你错过了我猜的退货声明......像这样的东西：..send(data, (error, body) => { return body; })

标签： node.js sails.js mailgun

【解决方案1】：

这是一个猜测：我认为mailgun.messages().send(...) 方法不会返回任何内容，因为它使用了经典回调。所以你总是会从中得到undefined。

但是你从回调中的 body 参数得到结果。您可以使用Promisify 将回调转换为promise 样式的方法。

const util = require('util');
const fs = require('fs');

const messages = mailgun.messages();

const sendPromisified = util.promisify(messages.send());
sendPromisified(data).then((body) => {
  // Do something with `body`
}).catch((error) => {
  // Handle mailgun error
});

// Async / await style
try {
   const mailBody = await sendPromisified(data);
} catch (err) {
   // handle mailgun error `err`
}

【讨论】：