獲取Http響應NodeJS

Question

嘗試在其中發出http請求的NodeJS（nodeJs的新手）中執行AWS Lambda。 Lambda執行結束時，我希望返回http請求的響應代碼和響應消息。

撥打http請求：

var executeRequest = function(request, callback) {

const req = https.request(request, (res) => {

  console.log('statusCode:', res.statusCode);
  console.log('headers:', res.headers);

  res.on('data', (d) => {
     process.stdout.write(d);
  });
  callback(res);
});

req.on('error', (e) => {
  console.error(e);
});

req.end(request.body);

};

Lambda代碼：

    exports.handler = (event, context, callback) => {

    // Formulate request 

    var result = executeRequest(request, function(response) {
         console.log("Response Code: ", response.statusCode);
         console.log("Response Message: ", response.statusMessage);
         // Successfully able to print the response above

        return response;
     });
     console.log("Result Response Code: ", result);
     console.log("Result Response Message: ", result);
     } 

我希望從Lambda返回response.statusCode和response.statusMessage作為響應

return{
    statusCode: <the code>,
    body: <the message>,
};

但是，結果填充為未定義。 如何提取所需的響應參數，以便可以正確返回它們？

**編輯：**建議更改后的代碼段：使用Promise進行編碼：

var executeRequest = function(request, callback) {

    return new Promise((resolve, reject) => {
        https.request(request, function(res) {
            if(res.statusCode==200 || res.statusCode==404) {
                resolve(res);
            }
            else {
                console.error(res);
                reject(res.statusCode);
            }
        }).end(request.body || '');
    });
};


exports.handler = (event, context, callback) => {

    // Formulate request 

    var value = executeRequest(request).then(function(result) {
  console.log("Result ", result);
  const response = { statusCode: 200, body: JSON.stringify('Hello from Lambda!') }; 
  return response;
 });

    console.log(value);
}

Answer 1

問題是您的executeRequest是異步的，而您的lambda對此一無所知，因此它將立即返回。

代替返回響應，將其作為第二個參數傳遞給callback （第一個是錯誤對象）

callback(null, response)

這部分將被執行，而無需等待executeRequest響應，其余代碼將被執行

var result = executeRequest(request, function(response) {
     console.log("Response Code: ", response.statusCode);
     console.log("Response Message: ", response.statusMessage);
     // Successfully able to print the response above

    return response;
 });

所以在這一點上

console.log("Result Response Code: ", result);
console.log("Result Response Message: ", result);

result仍然為空。

因此，您應該改做這樣的事情。

var result = executeRequest(request, function(response) {
     console.log("Response Code: ", response.statusCode);
     console.log("Response Message: ", response.statusMessage);
     // Successfully able to print the response above

     callback(null, response);
 });

Answer 2

嘗試這樣的事情。

exports.handler = function( event, context, callback ) { 
 //this is to allow function to return as soon as result is shown
 context.callbackWaitsForEmptyEventLoop = false;
 var request = ...//I expect request is a predefined value or define the request here.

 executeRequest(request).then( function( result ) { 


  //keep all console log before return.
  console.log("Result ", result);

  const response = { statusCode: 200, body: JSON.stringify('Hello from Lambda!') }; 

  callback(null, response);
  return;
 });
}
function executeRequest(request){
   return new Promise( ( resolve, reject ) => {

    https.request(request, function(res) {

     if(res.statusCode==200 || res.statusCode==404) {
        resolve(res);
     }else {
        console.error(res);
        reject(res.statusCode);
        return;
     }
    }).end(request.body || '');
  });
}

Answer 3

將您的Lambda代碼更改為以下代碼，

exports.handler = (event, context, callback) => {

    // Formulate request 

    var result = executeRequest(request, function(response) {
         console.log("Response Code: ", response.statusCode);
         console.log("Response Message: ", response.statusMessage);
         // Successfully able to print the response above

        callback(null, response);
     });

     } 

希望能幫助到你。