節點js多個http異步請求

新手在這裏。我嘗試獲取來自不同的HTTP數據源的數據，但我不能夠處理甚至「異步」的異步模式...節點js多個http異步請求

var express = require('express'); 
var app = express(); 
var https = require("https"); 
var timer = require("./my_modules/timer/timer.js"); 
var http = require('http'); 
var bodyParser = require('body-parser'); 
var async = require('async'); 
var request = require('request'); 

//These are my source from API. 
//Output is a Json file 
var sources = { 
    cnn: 'https://newsapi.org/v1/articles?source=cnn&sortBy?&apiKey=c6b3fe2e86d54cae8dcb10dc77d5c5fc', 
    bbc: 'https://newsapi.org/v1/articles?source=cnn&sortBy?&apiKey=c6b3fe2e86d54cae8dcb10dc77d5c5fc', 
    guardian: 'https://newsapi.org/v1/articles?source=cnn&sortBy?&apiKey=c6b3fe2e86d54cae8dcb10dc77d5c5fc', 
    othersource: "otherurls..." 
}; 

//I want to push the JSON object in this array 
var resultArray = []; 

//I setup a https GET request 
var getJson = function(url) { 
    https.get(url, (res) => { 
    var body = ''; 
    res.on('data', function(chunk) { 
     body += chunk; 
    }); 

    res.on('end', function() { 
     result = JSON.parse(body); 

     //push isn't working... 
     resultArray.push(result); 
    }); 

    }).on('error', function(e) { 
    console.log('Got an error', e); 
    }); 
} 

app.set('port', (process.env.PORT || 5000)); 
app.listen(
    app.get('port'),() => { 
    console.log('We are live on port: ', app.get('port')); 
    getJson(sources.cnn); 
    }); 


app.use(bodyParser.urlencoded({ 
    extended: true 
})); 
app.use(bodyParser.json()); 
app.use(function(req, res, next) { 
    res.setHeader('Content-Type', 'text/plain'); 
    res.status(404).send('Page not found !'); 
    res.status(503).send('Page not found, error 503'); 
}); 

console.log("resultArray:" + resultArray); 
//resultArray = empty...

我應該怎麼做的結果推到我的陣列？我找不到一種方法來設置一個工作回調函數來將結果推送到數組中。

對不起，這是Node.js中一個非常基本的問題。我希望它不是太多。

非常感謝您的幫助

來源

2017-10-28 Pierre Ktm

既然你已經在使用request包，你嘗試過爲簡單的東西：

request({ 
    url: sources.cnn, 
    json: true 
}, function(error, response, body) { 
    var articles = body.articles; 

    // or by case, depending on what you want 
    // resultArray = resultArray.concat(articles); 
    resultArray.push({ 
     cnn: articles 
    }); 

    console.log(resultArray); 
});

，而不是寫你自己的getJson功能？

來源

2017-10-28 18:23:38

謝謝Roby，你的要求更清晰！

我已經仔細閱讀本非常清晰，而且樂於助人文章：https://github.com/maxogden/art-of-node#callbacks

我想我的邏輯：

//main function 
function getJson(url, callback){ 
    request({ 
     url: url, 
     json: true, 
     callback:callback //added this 
     }, function(error, response, body) { 

      var articles = body.articles; 
      callback(articles); 
     }); 
} 

//this callback function will be passed to the main function as the 2nd parameter 
//it's possible to access "resultArray" ONLY from this function 
var result = function(e){ 
    resultArray.push(e); 
    console.log(resultArray); 
    }; 

//url and callback are passed as parameter 
getJson(sources.cnn, result);

感謝您的幫助

來源

2017-10-29 10:17:00

節點js多個http異步請求

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