XMLHTTPRequest error when integrating log4js AjaxAppender with Java backend - javascript

I am trying to do some frontend logging using log4js and sending the logs using the AjaxAppender to the server backend using Java. This is the frontend code that I use to initialize the logger, I've made sure the logger works with a DefaultLogger, and switched to AjaxAppender.
var log = log4javascript.getLogger();
var ajaxAppender = new log4javascript.AjaxAppender("logger");
ajaxAppender.setTimed(true);
ajaxAppender.setTimerInterval(10000); // send every 10 seconds (unit is milliseconds)
log.addAppender(ajaxAppender);
//convert to JSON format
jsonLayout = new log4javascript.JsonLayout(false, false); //readable, combineMessages
ajaxAppender.setLayout(jsonLayout);
ajaxAppender.addHeader("Content-Type", "application/json");
log.info("Begin Session")
This is the backend code written in Java, which gets the logs sent from the frontend.
#RequestMapping(value = "/logger", method = RequestMethod.POST)
#ResponseBody
public String logger(HttpServletRequest request, HttpServletResponse response) throws InterruptedException, IOException, SQLException {
System.out.println("Inside Logger");
System.out.println("Log:"+request);
return "Test successful:" + request;
}
However, I am getting the error XHR failed loading POST and the code doesn't seem to go inside the logger function ("Inside Logger" is not printed in terminal). I'm fairly new to working with Ajax and sending request between frontend and backend, is there a reason why the XMLHttpRequest is not going through?
Thanks!

404 means the service isn't reachable. Are you sure you've started the service and configged it properly?

Related

Custom error message in Google Apps Script Error object [duplicate]

This is a doPost function inside a Google App that returns a Hello World message.
function doPost(e){
return ContentService.createTextOutput('Hello World');
}
Now suppose I want to only accept valid JSON to be posted to this Google App endpoint and I want to send a respones with Bad Request status. How can I do that. Here's the pseudo code:
function doPost(e){
try{
const data = JSON.parse(e.postData.contents);
return ContentService.createTextOutput('Hello World');
}catch(err){
// Send Bad Request
}
}
Issue and workaround:
Unfortunately, in the current stage, ContentService cannot modify the status code. When I saw the official document of Class ContentService, such method cannot be found. Ref It seems that this is the current specification.
So in your situation, as the current workaround, how about returning the value as JSON data? By this, you can check the value using the key of JSON data. For example, how about the following sample script?
When the correct value without the error is returned,
return ContentService.createTextOutput(JSON.stringify({value: 'value'}));
When the value with the error is returned,
return ContentService.createTextOutput(JSON.stringify({error: 'Error message'}));
When you need .setMimeType(ContentService.MimeType.JSON), please add this.
Note:
When I searched about this at the Google issue tracker, I couldn't find it. So how about reporting this as the future request? Ref
Reference:
Class ContentService
Here's another workaround that allows raising errors on the client side for errors on the web app side. For example, a client might need to catch errors such as bad url args sent to the web app (i.e. the OP's question), or catch errors thrown by a method that is called from doGet() or doPost().
As far as I know, when an error is thrown downstream of doGet() or doPost(), a text error message is returned in the response, but the web app request itself succeeds, so there is no error thrown on the client side. As #Tanaike said, there still seems no way for a Google web app dev to throw an HTTP error from the app (like 400 Bad Request or 500 Internal Server Error).
The idea involves returning a function body from the web app, which the client can use to create and run a dynamic function via the Function() constructor (this assumes Javascript is available on the client).
So the web app can be written to:
return a function body that will throw an error for bad args, server method errors, etc.
return a function body that will return intended JSON when there is no error
This is a bit of a hack, but it unifies error handling on the client side. The client makes the http request, constructs a function using the function body returned in the response, and then runs this function, all in one try{} block. Then both Google-raised http errors and web app downstream errors can be caught in the catch{} block.
Example setup for a Google Apps Script client making a request to a Google web app:
(1) In the web app doGet() or doPost() function:
// this string will be returned by the webapp
var fnBody;
// for bad url args, return a fnBody that will throw an error with an indicative message
if(!urlArgsOk()) {
fnBody = "'use strict'; throw new Error('POST args error');";
}
// if url args are ok, call server method
else {
try {
// if the method call succeeds, return a fnBody that will return the intended JSON
var returnObj = myServerMethod(methodArgs);
fnBody = "'use strict'; return JSON.stringify(" + JSON.stringify(returnObj) + ");";
}
catch(serverErr) {
// if the method call fails, return a fnBody that will throw an error ...
// ... simple example shown here, but info from serverErr can be included in fnBody
fnBody = "'use strict'; throw new Error('server error');";
}
}
// return fnBody, which can be run via Function() on the client
return ContentService.createTextOutput(fnBody).setMimeType(ContentService.MimeType.TEXT);
(2) On the client side (Google apps script client making a POST request)
// Set the url, payload, and fetch options
var url = "https://script.google.com/_______/exec?arg1=val1&arg2=val2";
var payload = getPayloadString(); // whatever POST payload needs to be sent
var options = {
'method' : 'POST',
'contentType': 'application/json',
'muteHttpExceptions': false, // let Google http exceptions come through
'payload' : payload,
'headers': {authorization: "Bearer " + ScriptApp.getOAuthToken()}
};
// Send a request to the web app
try {
// make the POST request - this throws Google-generated HTTP errors if any
var response = UrlFetchApp.fetch(url, options);
// create the dynamic function from the fnBody returned
var responseFn = new Function(response.getContentText());
// run the function - this returns intended JSON content
// or throws web app downstream errors if any
var responseJson = responseFn();
}
catch(err) {
// handle either source of error
console.log(err.message);
}
There are potential security risks associated with dynamic code, so I'm not sure how widely applicable this might be. I might use this in an aplication that lives entirely in a private GCP domain, i.e. with the web app restricted to same-domain users and the client app also in the same domain. Some security is also added by the 'use strict' directive, which boxes the dynamic function in by setting its this to undefined (ref). But it's still a good idea to think through the dynamic code implications (ref1, ref2).

How to deliver javascript code using Springboot

I need to implement a requirement, where I need to deliver javascript code securely. My Idea is,
I will make the path as /something.js and in the controller, I will check the authentication, if not authenticate I will deliver console.error("Auth Failed").
How I can achieve the above scenario.
this is the simplest way using common request handler. works 100 %
#GetMapping(value = "/hello.js")
public void resources( HttpServletRequest httpRequest,
HttpServletResponse httpResponse) throws Exception {
//Authentication goes here or using handler interceptor
httpResponse.setContentType("text/javascript");
httpResponse.setHeader("MIME-type", "text/javascript");
httpResponse.getWriter().write(" function alertMan(msg) { \n alert(\"message:\"+msg); \n } ");
}

GET Service call is not getting called from Controller

i am trying to introduce Angular into one of my old application. But not sure why this is not calling the Service. Below is the Code in the JS File. Earlier i got error in browser saying $http cannot be resolved . So i just passed it in the function.
var app = angular.module('ldlApp', []);
app.controller('ldlController', function($scope,$http) {
console.log(" Inside Controller **** ");
$scope.message = 'Hello from LDL Controller !!!! ';
$scope.BLT_LDL_DECESION_LOAN_DATA = [];
console.log(" Going to Hit the Service ***** ");
$http.get("/Services/ldl/getdetails")
.then(function(response) {
$scope.BLT_LDL_DECESION_LOAN_DATA = response.data;
console.log("BLT_LDL_DECESION_LOAN_DATA:
"+JSON.stringify($scope.BLT_LDL_DECESION_LOAN_DATA));
});
});
Below is the REST Controller in java File
#RestController
public class LoanDecesionController {
#RequestMapping(value = "/Services/ldl/getdetails", method = RequestMethod.GET)
#ResponseBody
#Transactional
public List<LinkedHashMap<String, Object>> getdetails() throws Exception {
System.out.println(" Inside Service **** ");
List<LinkedHashMap<String, Object>> dataMap = new ArrayList<LinkedHashMap<String, Object>>();
LinkedHashMap<String, Object> responsedataMap = new LinkedHashMap<>();
responsedataMap.put("SUCESS", "Called the service ");
dataMap.add(responsedataMap);
return dataMap;
}
}
In Browser i could see message like
Inside Controller ****
Going to Hit the Service *****
Below is something i am seeing in network tab .
Request URL: https://*****-*****-*****.com/Services/ldl/getdetails
Request Method: GET
Status Code: 302 Found
Remote Address: 10.***.***.49:553
Referrer Policy: no-referrer-when-downgrade
But i am not getting the sysouts in controller. So whether the problem is really with response or is it hitting the service.
when using #Transactional and #ResquestMaping spring boot don't auto-configure URL mappings. remove #Transactional from your method and try to manage transactions somewhere else in your code
It looks like my existing application is blocking the URL and not allowing to hit any other URLs . Thanks everyone for the help and giving insight to the problem.

Sending messages from java servlet to javascript

I need help. I have single html-file running on my webserver. Via Javascript I'm sending data to my Java-Servlet on the same server via xhttp-request.
On Java's servlet side I can send a message back to the xhttp-request via a PrintWriter like below:
public void doGet(HttpServletRequest request, HttpServletResponse response)
{
PrintWriter theMessenger = response.getWriter();
theMessenger.print("Response data");
}
That all works fine. But now I need to send a message to the requesting html-file without the use of the servlet-response.
Are there any possibilities for sending data (strings as usual) to the html-file gathering those messages via onmessage-handler for example?
I tried this, but the messange never reaches it target:
String targetURL = CSConfig.GetRootURL() + "/myRequestingPage.html";
URL objUrl = new URL(targetURL);
HttpURLConnection urlCon = (HttpURLConnection) objUrl.openConnection();
urlCon.setRequestMethod("POST");
urlCon.setDoOutput(true);
DataOutputStream dataWriter = new DataOutputStream(urlCon.getOutputStream());
dataWriter.writeBytes(messageContent);
dataWriter.flush();
dataWriter.close();

POST data as json to a Servlet not working in Phantomjs

I am facing very strange issue here. I have a servlet running on my machine which renders my web page based on some input parameters.
Now, my screen capture with PhantomJS is not working if I try to send my data as a JSON object as a POST request type. For e.g. if I try:
Client side
var data = {"op": "get"};
page.open(address, 'POST', data, function (status) {
if (status !== 'success') {
console.log('[ERROR] :: Unable to fetch the address - ' + address + ", with data - " + data);
phantom.exit();
} else {
page.render(output);
}
console.log('processing...');
});
Server side
Now, on the server side, I am using Apache Velocity View templating so I have a single method which handles both get and post like :
public Template handleRequest(HttpServletRequest request, HttpServletResponse response,
Context context){
System.out.println(request.getParameter("op"));
//Always null
}
However, if I try sending my data from phantomjs as:
var data = "op=get&..."
It works
Also, at many places elsewhere in my code..I am doing Ajax POST requests to the same servlet and it works perfectly for all those request.
Would anybody explain why my servlet is not reading the JSON parameters passed from Phantomjs?
Servlets deal with simple request, so they only know how to parse (natively) HTTP parameters, either GET parameters from the URL, or POST parameters sent as application/x-www-form-urlencoded. Newer versions of the Servlet specification can also read multipart/form-data.
But there's nothing about JSON mentioned either in the Servlet or the HTTP specifications. So you must use a library that knows how to parse JSON and make the resulting object available in the Velocity context.

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