Why await is not working for node request module?

问题

I'm new to nodejs. I’m not seeing the response in ex 1, but i see in ex 2. Why? Await works for me in other places, using babel.

Ex 1

 let res = await request(url)
 console.log(res);
 console.log(res.body);

Ex 2

request(url, function (error, res, body) {
 if (!error && response.statusCode == 200) {
 console.log(body) 
 }
});

Await works in other places, I’m using babel and required modules for es6 and es7 features. For example, await works in squelize call, i validated. But it doesn’t work for request call. Why?

回答1:

You should only await on something that returns a Promise. I would definitely recommend reading up on Promises before you start working with async and await. You can probably get this example to work by creating your own wrapper function around request to make it return a promise, like so:

function doRequest(url) {
  return new Promise(function (resolve, reject) {
    request(url, function (error, res, body) {
      if (!error && res.statusCode == 200) {
        resolve(body);
      } else {
        reject(error);
      }
    });
  });
}

// Usage:

async function main() {
  let res = await doRequest(url);
  console.log(res);
}

main();

Edit: Alternatively, you can look into using request-promise instead of the regular request module.

回答2:

ES6

Usage: Where request is require('./await-request')

const init = async () => {
    try {
        const result = await request({
            uri: 'statdirectory/exchange?json',
            baseUrl: 'https://bank.gov.ua/NBUStatService/v1/',
            json: true
        })
        console.log(result)
    }
    catch (err) {
        console.error(err)
    }
}

Code:

// await-request.js
const request = require('request')

module.exports = async (value) => 
    new Promise((resolve, reject) => {
        request(value, (error, response, data) => {
            if(error) reject(error)
            else resolve(data)
        })
    })

回答3:

As @saadq says you can only 'await' functions returning Promise.

I like using Node.js's util package to promisify a function with callback. So util + request can be used like that:

const util = require('util')
const request = require("request");

const requestPromise = util.promisify(request);
const response = await requestPromise(url);
console.log('response', response.body);

Demo: https://runkit.com/mhmtztmr/node-js-request-with-async-await

回答4:

Try with the following NPM package

node-fetch

          var url = "http://www.google.com";
          try 
          {
            const response = await fetch(url);
            const json = await response.json();
            return {message:json.message,status:json.type};
          }
          catch(error)
          {
            console.log(error);
          }

Hope it works.

来源：https://stackoverflow.com/questions/38428027/why-await-is-not-working-for-node-request-module