Develop Reference

Node JS body-parser-xml Not Working

I want to handle both JSON- and XML-type requests, so I am using body-parser-xml in my node application.
My problem is the second XML element is not binding to req.body, but I get the first element value instead.
My code is:
var loopback = require('loopback');
var boot = require('loopback-boot');
var cfenv = require('cfenv');
var bodyParser = require("body-parser");
var cookieParser = require('cookie-parser');
require('body-parser-xml')(bodyParser);
var app = module.exports = loopback();
var appEnv = cfenv.getAppEnv();
app.use(bodyParser.json());
app.use(bodyParser.xml({
limit: '1MB', // Reject payload bigger than 1 MB
xmlParseOptions: {
normalize: true, // Trim whitespace inside text nodes
normalizeTags: false, // Transform tags to lowercase
explicitArray: false // Only put nodes in array if >1
}
}));
app.use(bodyParser.urlencoded({
"extended": true
}));
// boot scripts mount components like REST API
boot(app, __dirname);
app.start = function() {
// start the web server
return app.listen(process.env.PORT || 3000, function() {
console.log("env port" + process.env.PORT);
app.emit('started');
var baseUrl = app.get('url').replace(/\/$/, '');
console.log('Web server listening at: %s', baseUrl);
if (app.get('loopback-component-explorer')) {
var explorerPath = app.get('loopback-component-explorer').mountPath;
console.log('Browse your REST API at %s%s', baseUrl, explorerPath);
}
});
};
// start the server if `$ node server.js`
if (require.main === module) {
app.start();
}
My Routes:
module.exports = function(app) {
var router = app.loopback.Router();
var User = app.models.pusers;
var js2xmlparser = require("js2xmlparser");
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "X-Requested-With");
if (req.get("content-type") !== 'undefined') {
if (req.get("content-type") == 'application/json') {
res.setHeader('content-type', req.get("content-type"));
} else if (req.get("content-type") == 'application/xml') {
res.setHeader('content-type', req.get("content-type"));
}
}
next();
});
app.middleware('initial', function logResponse(req, res, next) {
res.on('finish', function() {});
req.on('end', function(data) {});
req.on('data', function(data) {
// the request was handled, print the log entry
console.log(req.method, req.originalUrl, res.statusCode);
if (req.get("content-type") == 'application/xml') {
console.log("xml data's :" + data);
} else if (req.get("content-type") == 'application/json') {
console.log("json data's :" + data);
}
});
next();
});
function responseHandler(req, res, data) {
if (req.get("content-type") == 'application/json') {
return JSON.stringify(data);
} else if (req.get("content-type") == 'application/xml') {
return js2xmlparser("response", JSON.stringify(data));
} else
return data;
}
router.post('/login', function(req, res) {
var response = {};
console.log(req.body);
console.log(req.body.username);
try {
User.find({
where: {
name: req.body.username
}
}, function(err, data) {
if (err) {
response = {
"error": true,
"message": "Error fetching data"
};
} else {
if (data.length != 0) {
if (data[0].name == req.body.username && data[0].password == req.body.password) {
response = {
"error": false,
"data": "Success"
};
} else {
response = {
"error": false,
"data": "Password is incorrect"
};
}
} else if (data.length == 0) {
response = {
"error": false,
"data": "Username is incorrect"
};
}
}
console.log("Check login");
res.end(responseHandler(req, res, response));
});
} catch (ex) {
console.error("Error while retrive all data from User Model by name", ex);
res.end(responseHandler(req, res, "Error while inserting User Model by name"));
}
});
app.use(router);
}
How can i solve this problem?

I found that if you encapsulate the whole data into a single XML tag, you receive the complete set. For example:
<data>
<username>somename</username>
<password>passwd</password>
</data>
Then access it in node.js as:
req_xml = req.body["data"];
console.log(req_xml["username"]);
console.log(req_xml["password"]);

ErrorType: undefined is not a function (node)

Hi i have a little problem, a console send me this error: ErrorType: undefined is not a function, var server = http.createSever(function(request, reposne). Can you help me? This is my 1st post in this website.
This is a code:
var http = require('http');
var fs = require('fs');
var path = require('path');
var mime = require('mime');
var cache = {};
function send404(response){
response.writeHead(404, {'Content-Type': 'text/plain'});
response.write('Błąd 404');
response.end();
}
function sendFile(response, filePath, fileContent){
response.writeHead(
200,
{"content-type": mime.lookup(path.basename(filePath))}
);
response.end(fileContent);
}
function serverStatic(response, cache, absPath){
if(cache[absPath]){
sendFile(response, absPath, cache[absPath]);
}
else {
fs.exists(abs.Path, function(exists){
if(exists){
fs.readFile(absPath, function(err, data){
if(err){
send404(response);
}
else {
cache[absPath] = data;
sendFile(response, absPath, data);
}
});
}
else {
send404(response);
}
});
}
}
var server = http.createSever(function(request, reposne){
var filePath = false;
if(request.url == '/'){
filePath = 'public/index.html';
}
else {
filePath = 'public' + request.url;
}
var absPath = './'+filePath;
serverStatic(response, cache, absPath);
});
server.listen(3000, function(){
console.log("port 3000");
});

It's createServer, not createSever (note the r before the v).

Node.js error "terminate called after throwing an instance of 'std::bad_alloc' what(): std::bad_alloc"

I am using node.js on digital ocean and trying to run a file upload / download server.
To make sure the server runs in the background and does not quit on error, I am using the following
nohup nodejs server.js &
I am using nodejs instead of the node command because that is what digital ocean recommends.
This server is almost exlusively for uploading and downloading files. This works, for about two files, but then the server crashes with the following error:
"terminate called after throwing an instance of 'std::bad_alloc' what(): std::bad_alloc"
I have no idea what is causing this, and I would appreciate any help. Preventing the crash would be great but also making it so the node server would not crash would also be great. I thought that is what nohup does, but apparently not. (I also haven't been able to get forever working correctly).
Here is the code for my server:
var http = require('http'),
url = require('url'),
util = require('util'),
path = require('path'),
fs = require('fs'),
qs = require('querystring');
var formidable = require('formidable'),
mime = require('mime');
var account = {username: 'test', password: 'etc'};
var accounts = [account],
port = 9090,
function dirTree(filename) {
var stats = fs.lstatSync(filename),
info = {
name: path.basename(filename),
path: ip + ':' + port + '/uploads/finished/' + path.basename(filename),
type: mime.lookup(filename).substring(0, 5)
};
if (stats.isDirectory()) {
info.type = "folder";
info.children = fs.readdirSync(filename).map(function(child) {
return dirTree(filename + '/' + child);
});
}
return info;
}
http.createServer(function(request, response) {
if(request.method.toLowerCase() == 'get') {
var filePath = './content' + request.url;
if (filePath == './content/') {
filePath = './content/home.html';
}
if (filePath == './content/feed') {
a = dirTree('./content/uploads/finished');
response.end(JSON.stringify(a));
}
var extname = path.extname(filePath);
var contentType = mime.lookup(extname);
fs.exists(filePath, function (exists) {
if (exists) {
fs.readFile(filePath, function (error, content) {
if (error) {
response.writeHead(500);
response.end();
}
else {
response.writeHead(200, {'Content-Type': contentType});
response.end(content, 'utf-8');
}
})
} else {
response.writeHead(404);
response.end();
}
});
}
if (request.method.toLowerCase() == 'post') {
var form = new formidable.IncomingForm;
if (request.url == '/verify') {
form.parse(request, function (err, fields, files) {
for (i = 0; i < accounts.length; i++) {
if (fields.username == accounts[i].username && fields.password == accounts[i].password) {
fs.readFile('./content/uploadForm.html', function (error, content) {
if (error) {
response.end('There was an error');
} else {
response.end(content);
}
});
} else {
fs.readFile('./content/invalidLogin.html', function (error, content) {
if (error) {
response.end('There was an error');
} else {
response.end(content);
}
});
}
}
});
} else if (request.url == '/upload') {
var oldPath,
newPath,
fileName;
form.uploadDir = './content/uploads/temp/';
form.keepExtensions = true;
form.parse(request, function (err, fields, files) {
type = files['upload']['type'];
fileName = files['upload']['name'];
oldPath = files['upload']['path'];
newPath = './content/uploads/finished/' + fileName;
});
form.on('end', function () {
fs.rename(oldPath, newPath, function (err) {
if (err) {
response.end('There was an error with your request');
console.log('error')
} else {
response.end('<h1>Thanks for uploading ' + fileName + '<h1>');
}
});
});
}
}
}).listen(port);
console.log('listening on ' + port);

It looks like your script is just run out of the available memory.
Most likely you upload or download very large file and you read complete file in memory while receiving or sending.
You should rewrite you code using stream operations and process files chunk-by-chunk instead.

Invalid file while saving .png image from webcam via canvas dataURL using node.js

I am trying to do a little app that lets users take a picture using their webcam and send that picture to the server so that it gets stored as a .png file. Right now almost everything is working fine, you can use the camera to take the picture and then send the form, it then creates a .png file but it appears to be invalid, not an image. Am I missing something in this code?
Thanks in advance.
This is the front end code:
window.addEventListener("DOMContentLoaded", function() {
var canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
video = document.getElementById("video"),
videoObj = { "video": true },
errBack = function(error) {
console.log(error.code);
};
// Put video listeners into place
if(navigator.getUserMedia) {
navigator.getUserMedia(videoObj, function(stream) {
video.src = stream;
video.play();
}, errBack);
} else if(navigator.webkitGetUserMedia) {
navigator.webkitGetUserMedia(videoObj, function(stream){
video.src = window.webkitURL.createObjectURL(stream);
video.play();
}, errBack);
}
else if(navigator.mozGetUserMedia) {
navigator.mozGetUserMedia(videoObj, function(stream){
video.src = window.URL.createObjectURL(stream);
video.play();
}, errBack);
}
// Trigger photo snap
document.getElementById("snap").addEventListener("click", function() {
context.drawImage(video, 0, 0, 640, 480);
var dataURL = canvas.toDataURL('image/png').replace(/^data:image\/png;base64,/,'');
var imginput = document.getElementById('imgdata');
imginput.value = dataURL;
});
}, false);
And this is the code on the node.js server:
// Load modules / dependencies
var http = require('http');
var fs = require('fs');
var qs = require('querystring');
var config = JSON.parse(fs.readFileSync('config.json'));
var port = config.port;
var server = http.createServer(function(request, response) {
console.log('Received request: ' + request.url);
fs.readFile('./' + request.url, function(error, data) {
if (error) {
response.writeHead(404, {'Content-type':'text/plain'});
response.end('Sorry the page was not found');
} else if (request.method == 'POST') {
processPost(request, response, function() {
console.log(response.post);
response.writeHead(200, "OK", {'Content-Type': 'text/plain'});
response.end();
});
} else {
response.writeHead(200, {'Content-type':'text/html'});
response.end(data);
};
})
});
function processPost(request, response, callback) {
var queryData = "";
if(typeof callback !== 'function') return null;
if(request.method == 'POST') {
request.on('data', function(data) {
queryData += data;
fs.writeFile('image.png', queryData, 'base64');
});
request.on('end', function() {
callback();
});
} else {
response.writeHead(405, {'Content-Type': 'text/plain'});
response.end();
}
}
server.listen(port, function() {
console.log('Listening ' + port);
});

I finally got it working by using express and changing the server code to the following:
var fs = require("fs");
var express = require("express");
var app = express();
app.use(express.static(__dirname + '/'));
app.use(express.bodyParser());
app.get('*', function(req, res) {
res.sendfile('./index.html');
});
app.post('/', function(req, res) {
var imgdata = req.body.userimg;
fs.writeFile('image.png', imgdata, 'base64');
res.sendfile('./index.html');
});
app.get("*", function(request, response){
response.send("Page not found", 404);
});
app.listen(8080);
console.log("App listening on port 8080");
It now saves the image captured from the webcam as a valid .png file.

how to serve a file (exe or rar ) to a client for download from node.js server?

I have a a node.js server that serves an index.html with a text input for a password.
After a serverside password check the download should start for the client.
The client shouldn't be able to see the location path where the file lies on the server.
here is my server.js:
var
http = require('http'),
qs = require('querystring'),
fs = require('fs') ;
console.log('server started');
var host = process.env.VCAP_APP_HOST || "127.0.0.1";
var port = process.env.VCAP_APP_PORT || 1337;
http.createServer(function (req, res) {
if(req.method=='GET') {
console.log ( ' login request from ' + req.connection.remoteAddress );
fs.readFile(__dirname +'/index.html', function(error, content) {
if (error) {
res.writeHead(500);
res.end();
}
else {
res.writeHead(200, { 'Content-Type': 'text/html' });
res.end(content, 'utf-8');
}
});
} // method GET end
else{ // method POST start
console.log('POST request from ' + req.connection.remoteAddress);
var body = '';
req.on('data', function (data) {
body += data;
if (body.length > 500) {
// FLOOD ATTACK OR FAULTY CLIENT, NUKE REQUEST
req.connection.destroy(); console.log('too much data')}
});
req.on('end', function () {
var postdata = qs.parse(body);
var password = postdata.passwordpost ;
if (password == '7777777') {
console.log('the password is right, download starting');
// ??????????????????????????????????? here I need help from stackoverflow
}
else{
console.log ('password wrong');
fs.readFile(__dirname +'/wrongpassword.html', function(error, content) {
if (error) {
res.writeHead(500);
res.end();
}
else {
res.writeHead(200, { 'Content-Type': 'text/html' });
res.end(content, 'utf-8');
}
});
}
}); // req on end function end
}
}).listen(port, host);
the part where I need help is marked with ????????
here is my index.html:
<html>
<body>
<br> <br>
please enter your password to start your download
<br> <br>
<form method="post" action="http://localhost:1337">
<input type="text" name="passwordpost" size="50"><br><br>
<input type="submit" value="download" />
</form>
</body>
</html>
Do you know how to do this?

Sure, you can use this in your code :
res.setHeader('Content-disposition', 'attachment; filename='+filename);
//filename is the name which client will see. Don't put full path here.
res.setHeader('Content-type', 'application/x-msdownload'); //for exe file
res.setHeader('Content-type', 'application/x-rar-compressed'); //for rar file
var file = fs.createReadStream(filepath);
//replace filepath with path of file to send
file.pipe(res);
//send file

You needs to declare and require the path: path = require("path")
then can do:
var uri = url.parse(request.url).pathname
, filename = path.join(process.cwd(), uri);
path.exists(filename, function(exists) {
if(!exists) {
response.writeHead(404, {"Content-Type": "text/plain"});
response.write("404 Not Found\n");
response.end();
return;
}
response.writeHead(200);
response.write(file, "binary");
response.end();
}
check these complete example.

If you are willing to use express web framework, then it can be done in a much easier way.
app.get('/download', function(req, res){
var file = __dirname + 'learn_express.mp4';
res.download(file); // Sets disposition, content-type etc. and sends it
});
Express download API

I found some additional information about fs.createReadStream() ( especially error handling ) here and combined it with the answer of user568109. Here is my working downloadserver:
var
http = require('http'),
qs = require('querystring'),
fs = require('fs') ;
console.log('server started');
var host = process.env.VCAP_APP_HOST || "127.0.0.1";
var port = process.env.VCAP_APP_PORT || 1337;
http.createServer(function (req, res) {
if(req.method=='GET') {
console.log ( ' login request from ' + req.connection.remoteAddress );
fs.readFile(__dirname +'/index.html', function(error, content) {
if (error) {
res.writeHead(500);
res.end();
}
else {
res.writeHead(200, { 'Content-Type': 'text/html' });
res.end(content, 'utf-8');
}
});
} // method GET end
else{ // method POST start
console.log('POST request from ' + req.connection.remoteAddress);
var body = '';
req.on('data', function (data) {
body += data;
if (body.length > 500) {
// FLOOD ATTACK OR FAULTY CLIENT, NUKE REQUEST
req.connection.destroy(); console.log('too much data')}
});
req.on('end', function () {
var postdata = qs.parse(body);
var password = postdata.passwordpost ;
if (password == '7777777') {
console.log('the password is right, download starting');
res.setHeader('Content-disposition', 'attachment; filename='+'test1.exe');
//filename is the name which client will see. Don't put full path here.
res.setHeader('Content-type', 'application/x-msdownload'); //for exe file
res.setHeader('Content-type', 'application/x-rar-compressed'); //for rar file
var readStream = fs.createReadStream('/test1.exe');
//replace filepath with path of file to send
readStream.on('open', function () {
// This just pipes the read stream to the response object (which goes to the client)
readStream.pipe(res);
});
// This catches any errors that happen while creating the readable stream (usually invalid names)
readStream.on('error', function(err) {
console.log (err) ;
res.writeHead(200, { 'Content-Type': 'text/html' });
res.end('an error occured', 'utf-8');
});
//send file
}
else{
console.log ('password wrong');
fs.readFile(__dirname +'/wrongpassword.html', function(error, content) {
if (error) {
res.writeHead(500);
res.end();
}
else {
res.writeHead(200, { 'Content-Type': 'text/html' });
res.end(content, 'utf-8');
}
});
}
}); // req on end function end
}
}).listen(port, host);