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Sending file through HTTP request

I tried to receive the file and store it in the multer storage
Node js code
enter code here
app.post('/createLicence', upload.single('photo'),function(req, res ,next) {
// any logic goes here
console.log("filename" ,req.body.name)
if (!req.file) {
console.log("No file received");
return res.send({
success: false
});
} else {
console.log('file received');
var function_name = 'createLicence'
var arguments_array = [req.file.path,'Raghav','Mumbai','Approved']
invoke = require('/Users/sanjeev.natarajan/fabric-samples/fabcar/invoke.js');
invoke.invokechaincode(function_name,arguments_array)
return res.send({
success: true
})
}
});
but i am receiving no file is receivedi have send the request through postman

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From : https://www.npmjs.com/package/multer
In order to use the multer package, you have first to define a few parameters so that it can work on your fileDirectory.
In your server.js :
let multer = require('multer');
let storage = multer.diskStorage({
destination: function(req, file, cb) {
cb(null, '/path/to/storage/')
},
filename: function(req, file, callback) {
callback(null, file.originalname + '-' + Date.now());
}
});
let upload = multer({
storage: storage
});
Now, configure your route
router.route('/your/payload')
.post(authController.isAuthenticated, upload.any(), albumController.postFile)
Note that upload.any() will allow you to upload multiple different formatted files at once. Feel free to use any other kind of upload.method() depending on your needs.
From this point, multer already is doing its job, however you might want to keep track of the files uploaded on your server.
So, in your own module, the logic is pretty much straight forward :
(I'm assuming that you're using mongoose models since you're not giving much information, but that's not the relevant part anyway)
exports.postFile = async (req, res) => {
if (!req || !req.files || !req.files[0]) return res.status(400).send("Bad request.");
for (let i = 0; req.files[i]; i++) {
await File.create({
path: req.files[i],
originalName: req.files[i].originalName,
mimetype: req.files[i].mimetype,
owner: req.user.userId
}, (err, file) => {
if (err) console.log("Something went wrong: " + err); else {
// Do something with file
}
});
}
return res.status(418).send("I'm a teapot.");
}
This configuration and middleware use is ONLY for testing purpose, never ever let anyone upload something to your server without carefully handle that uploading process (file integrity, resource management, ...). An open uploading system can become a very wide backdoor getting straight to your server.
Hope this helps,
regards.

How to parse an object sent from react frontend in express.js?

So in my react front-end, I am using the 'react-drop-to-upload' module to allow the user to drag a file and upload. I followed the example on the npm module page and created a handler called handleDrop. The code looks like:
handleDrop(files) {
var data = new FormData();
alert((files[0]) instanceof File);
files.forEach((file, index) => {
data.append('file' + index, file);
});
fetch('/file_upload', {
method: 'POST',
body: data
});
}
At my express backend, I have the following code:
app.post('/file_upload', function(req , res){
var body = '';
req.on('data', function (data) {
body += data;
});
var post = "";
req.on('end', function () {
//post = qs.parse(body);
console.log(body);
// this won't create a buffer for me
//var fileBuffer = new Buffer(body);
//console.log(fileBuffer.toString('ascii'));
//pdfText(body, function(err, chunks) {
//console.log(chunks);
//});
});
//console.log(typeof post);
});
If I drop a txt file and do a console log on the body, it would give me:
------WebKitFormBoundaryqlp9eomS0BxhFJkQ
Content-Disposition: form-data; name="file0"; filename="lec16.txt"
Content-Type: text/plain
The content of my data!
------WebKitFormBoundaryqlp9eomS0BxhFJkQ--
I am trying to use the pdfText module which takes in a buffer or a pathname to the pdf file, extract text from it into an array of text 'chunks' . I want to convert the body object into a buffer using var fileBuffer = new Buffer(body); but that won't work. Can someone help me with this? Thanks!

You need a parser for multi-part data. You can look into multer regarding that.
Example code for you,
app.post('/file_upload', function(req , res){
var storage = multer.diskStorage({
destination: tmpUploadsPath
});
var upload = multer({
storage: storage
}).any();
upload(req, res, function(err) {
if (err) {
console.log(err);
return res.end('Error');
} else {
console.log(req.body);
req.files.forEach(function(item) {
// console.log(item);
// do something with the item,
const data = fs.readFileSync(item.path);
console.log(data);
});
res.end('File uploaded');
}
});
});
To understand the example code in depth, head here. Remember, you will get the file data as a buffer and not as actual data.

How do I write an image to buffer using native Node JS HTTP library?

I am really new to JavaScript and Node JS. I have various image URLs that I want to buffer. I have tried the request npm module but want a lower level library for what I want to achieve.
For example:
http://assets.loeildelaphotographie.com/uploads/article_photo/image/128456/_Santu_Mofokeng_-_TOWNSHIPS_Shebeen_Soweto_1987.jpg
I see lots of examples that suggest using the request module or examples that save files to disk. However, I cannot find an HTTP GET request example that simply buffers the image so I can pass to another function. It needs to have an "end" event so I upload the buffered image data with confidence in another step. Is there a sample pattern or "how to" on this someone could provide? Thanks!

This is the native way:
var http=require('http'), imageBuffer;
http.get(
'http://www.kame.net/img/kame-anime-small.gif',
function(res) {
var body=new Buffer(0);
if (res.statusCode!==200) {
return console.error('HTTP '+res.statusCode);
}
res.on('data', function(chunk) {
body=Buffer.concat([body, chunk]);
});
res.on('end', function() {
imageBuffer=body;
});
res.on('error', function(err) {
console.error(err);
});
}
);
// Small webserver serving the image at http://127.0.0.1:4567
http.createServer(function(req, res) {
res.write(imageBuffer || 'Please reload page');
res.end();
}).listen(4567, '127.0.0.1');
and using request (encoding:null for binary response):
var request=require('request'), imageBuffer;
request({
uri: 'http://www.kame.net/img/kame-anime-small.gif',
encoding: null
}, function(err, res, body) {
if (err) {
return console.error(err);
} else if (res.statusCode!==200) {
return console.error('HTTP '+res.statusCode);
}
imageBuffer=body;
});
// Small webserver serving the image at http://127.0.0.1:4567
require('http').createServer(function(req, res) {
res.write(imageBuffer || 'Please reload page');
res.end();
}).listen(4567, '127.0.0.1');

Here's a simple example using the built-in streaming that the http response has:
var http = require('http');
var fs = require('fs');
var file = fs.createWriteStream("test.png");
var request = http.get("some URL to an image", function(response) {
response.pipe(file);
});
I ran this myself and successfully downloaded an image from an external web site and saved it to a file and then loaded the file into the browser to see the same image.

How do I compile jade on request rather than just server start?

I'm looking to compile my jade on server request/response that way I can make changes to the jade file and see it in real time, rather than having to restart the server every time. This is the fake mockup I have so far.
var http = require('http')
, jade = require('jade')
, path = __dirname + '/index.jade'
, str = require('fs').readFileSync(path, 'utf8');
function onRequest(req, res) {
req({
var fn = jade.compile(str, { filename: path, pretty: true});
});
res.writeHead(200, {
"Content-Type": "text/html"
});
res.write(fn());
res.end();
}
http.createServer(onRequest).listen(4000);
console.log('Server started.');
I hope I made myself clear!

You're only reading the file once, on server startup. If you wanted to have it read changes you'd have to read it on request, meaning your mock-up would look more like:
function onRequest(req, res) {
res.writeHead(200, {
"Content-Type": "text/html"
});
fs.readFile(path, 'utf8', function (err, str) {
var fn = jade.compile(str, { filename: path, pretty: true});
res.write(fn());
res.end();
});
}
Something like that would read the file every time, which is probably okay for development purposes, but if you only wanted to reload/process the file when something changed, you might use a file watcher (fs.watch might fit this bill).
Something like this (just an untested example as an idea):
var fn;
// Clear the fn when the file is changed
// (I don't have much experience with `watch`, so you might want to
// respond differently depending on the event triggered)
fs.watch(path, function (event) {
fn = null;
});
function onRequest(req, res) {
res.writeHead(200, {
"Content-Type": "text/html"
});
var end = function (tmpl) {
res.write(tmpl());
res.end();
};
if (fn) return end(fn);
fs.readFile(path, 'utf8', function (err, str) {
fn = jade.compile(str, { filename: path, pretty: true});
end(fn);
});
}

Responding an image (via pipe and response.end()) leads into strange behaviour

I used this code to pipe an image to my clients:
req.pipe(fs.createReadStream(__dirname+'/imgen/cached_images/' + link).pipe(res))
it does work but sometimes the image is not transferred completely. But no error is thrown neither on client side (browser) nor on server side (node.js).
My second try was
var img = fs.readFileSync(__dirname+'/imgen/cached_images/' + link);
res.writeHead(200, {
'Content-Type' : 'image/png'
});
res.end(img, 'binary');
but it leads to the same strange behaviour...
Does anyone got a clue for me?
(abstracted code...)
var http = require('http');
http.createServer(function (req, res) {
Imgen.generateNew(
'virtualtwins/www_leonardocampus_de/overview/28',
'www.leonardocampus.de',
'overview',
'28',
null,
[],
[],
function (link) {
fs.stat(__dirname+'/imgen/cached_images/' + link, function(err, file_info) {
if (err) { console.log('err', err); }
console.log('file info', file_info.size);
res.writeHead(200, 'image/png');
fs.createReadStream(__dirname+'/imgen/cached_images/' + link).pipe(res);
});
}
);
}).listen(13337, '127.0.0.1');
Imgen.generateNew just creates a new file, saves it to the disk and gives back the path (link).

I've used this before and all that is needed is that in the function (req, res) {:
var path = ...;
res.writeHead(200, {
'Content-Type' : 'image/png'
});
fs.createReadStream(path).pipe(res);
where path is the computed path to the file to send. .pipe() will transfer the data from the read stream to the write stream and call end when the read stream ends, so there is no need to use res.end() after.

What the problem was: I had 2 different writeStreams! If WriteStream#1 is closed, the second should be closed too and then it all should be piped.
But node is asynchronous so while one has been closed, the other one hasn't. Even the stream.end() was called... well you always should wait for the close event!