閱讀的NodeJS文件，使節點休息客戶端調用來獲取相關的數據和JSON

Question

我讀書用fs.readFileSync並獲得每個文檔，我正在使用的客戶休息API調用JSON文件添加檢索響應作爲元素。員額。一旦我得到響應，我想將接收到的內容放入另一個JSON文件，該文件是輸入JSON的副本，除了從client.post調用接收的數據之外的附加元素。不過可能是因爲client.post的異步性質，我無法添加元素來輸出JSON。我是NodeJS的新手。你能幫我找我失蹤的地方嗎？下面是代碼和數據

數據：

[ 
    { 
     "ticker": "CLYD" 
    }, 
    { 
     "ticker": "EGH" 
    } 
] 

代碼：

var fs = require('fs'); 
var Client = require('node-rest-client').Client; 

var data = fs.readFileSync(__dirname + "/data/stocks.json", "utf8"); 
processData(data); 

function processData (data) { 

    var obj = JSON.parse(data); 

    for (j = 0; j < obj.length; j++) { 

     obj[j].stockInformation = getValuesForTicker (obj[j].ticker.trim()); 

    } 

    var jsonOutput = JSON.stringify(obj,null,'\t'); 
    fs.writeFileSync(__dirname + "/data/response.json", jsonOutput); 

}; 

function getValuesForTicker (ticker) { 

    /** 
    * More details and samples at https://www.npmjs.com/package/node-rest-client 
    */ 
    var client = new Client(); 
    var values; 

    // set content-type header and data as json in args parameter 
    var args = { 
     data: { "ticker" : ticker}, 
     headers: { "Content-Type": "application/json", "Accept" : "application/json" } 
    }; 

    var responseToRequest = client.post("https://url.providing.response.as.json.content/", args, function (data, response) { 
//   parsed response body as js object 
     values = JSON.parse(JSON.stringify(data)).price; 
    }); 
    return values; 

}; 

Answer 1

由於getValueForTicker使得異步調用來獲取數據應該調用回調一旦數據被收到（或更好的承諾）並且不返回結果（當前undefined作爲在賦值之前返回的值而返回）

function getValuesForTicker (ticker, callback) { 

    /** 
    * More details and samples at https://www.npmjs.com/package/node-rest-client 
    */ 
    return new Promise(function(resolve, reject) { 

      var client = new Client(); 
      var values; 

      // set content-type header and data as json in args parameter 
      var args = { 
       data: { "ticker" : ticker}, 
       headers: { "Content-Type": "application/json", "Accept" : "application/json" } 
      }; 

      var responseToRequest = 
      client.post("https://url.providing.response.as.json.content/", args, function (data, response) { 
     //   parsed response body as js object 
      values = JSON.parse(JSON.stringify(data)).price; 
      resolve(values) 
     }); 

    }; 
}) 

，並獲得一次數據異步調用完成後，您將需要再調用函數如下：

 getValuesForTicker(obj[j].ticker.trim()) 
     .then(function(val) { 
      obj[j].stockInformation = val 
     }) 

考慮到你是新來的Node.js這將是很難get.Take一些時間來了解回調和承諾第一。