I need to get number of items of specific directory in Node.js
If I get the items like
var dirItems = fs.readdirSync(__dirname+'/my_dir');
and then get specific item like
dirItems[1]
everything is ok
But if I try to get their number like
dirItems.length
or
Object.keys(dirItems).length
the page doesn't work in the browser
How to get the number of directory items?
UPDATED
My full code:
var http = require('http'),
fs = require('fs');
http.createServer(function(req, res) {
var dirItems = fs.readdirSync(__dirname+'/my_dir');
res.writeHead(200, {'Content-Type': 'text/html'});
res.end(dirItems.length);
}).listen(80, 'localhost');
I was able to reproduce the error nyou get.
res.end() for the basic http server class is very picky about what you send it. You must give it a string (the error you got should have been a big clue here).
So, change this:
res.end(dirItems.length);
to this:
res.end(dirItems.length.toString());
And, it works for me. I was able to reproduce your original error and then make it work by making this simple change.
Logically, you can only send string data as an http response so apparently res.end() isn't smart enough to attempt a string conversion on its own. You have to do it yourself.
FYI, if you use a higher level framework like Express, it is more tolerant of what you send it (it will attempt a string conversion in a situation like this).
Here is how I would do it:
const fs = require('fs');
const dir = './somedir';
fs.readdir(dir, (err, files) => {
console.log(files.length);
});
Related
The title makes no sense to a closest-to-the-box person, but it will make sense.
I'm trying to make a custom-code HTTP server. the code works completely, but I want to add a 404 page.
when you get the 404 page, I want to show more than text.
this is what I have without that addition:
http = require("http");
fs = require("fs");
server = {};
server.http = http.createServer((request, response)=>{
request.path = request.url.split("?")[0];
if(request.url.split("?").length>1){
request.query = request.url.split("?")[1];
request.query = request.query.split('&');
var result = {};
for (var i = 0; i < request.query.length; i++) {
var cur = request.query[i].split('=');
result[decodeURIComponent(cur[0])] = decodeURIComponent(cur[1]);
}
request.query = result;
}
console.clear();
console.log(request.headers, request.path, request.query);
fs.readFile(`Public/HTTP/Scripts${request.path}.js`, "utf-8", (directError, script)=>{
if(directError){
if(directError.message == `ENOENT: no such file or directory, open 'Public/HTTP/Sripts${request.path}.js'`){
//this is where I would like that code. i was thinking a for loop would work but then i got really confused, so, here i am.
}
} else {
fs.readFile(`Public/HTTP/Send${request.path}.file`, (A, sendFile)=>{
eval(script);
});
}
})
});
server.http.listen();
console.clear();
The question without the extras is:
How do I go through file folders backward until I find a folder with the file I need?
I don't even know what I mean, but even more broken down in an example:
/a/path/to/a/file_that/doesn't_exist is request.url.
a, to, and file_that all have the file with the 404 response code.
I want it to get file_thats 404 script because it is the last.
I am so sorry if you still don't understand me. I'm new here and Idk how else to explain it.
Using the Express NodeJS Library is the industry standard framework for defining routes.
Express automatically finds the farthest file and sends an error.
If you use express, you can write
app.use(function (req, res, next) {
res.status(404);
res.send("public/error-404.html") //Where error-404.html is your custom HTML Page
return;
});
You can follow the official guide to implement Express in your app
I'm trying to understand how to deal(in a secure way) with Path Traversal.
For example an application receives from a client a file name via REST API in JSON, look for it in the non-accessible(by outside) directory and retrieve a response with the file:
app.get('/', (req, res) => {
const fileName = req.body.fileName;
// some code...
fs.stat(`./nonAccessibleDir/${fileName}`, async function(err, stat) {
// some code...
});
// some code...
}
The problem with the above approach is that a client can send something like "../" in the fileName request and it will "eat" it without an issue. How can one deal with this kind of scenarios, what and how I should fix this vulnerability, please?
Update:
Sorry, but I forgot to mention that I know I should check the input I receive, but what if I need to pass the "/" and "." in the input? Also, if I don't need this characters, is that all I need to check to remove the Path Traversal vulnerability?
An easy way would be to validate the fileName through a regex that detects any ../ segments and returns an error if any are present.
if (fileName.match(/\.\.\//g) !== null) {
// return an api error
}
You could have quite a tight validation rule that prevents any forward slashes in fileName at all, making it only possible to point to a file directly in your desired directory.
I split a video file into two using the split-file module.
There are no file part extensions. They seem like: gan-1, gan-2
I am hosting these two files on my own server.
http://bilketay.com/download/gan-1
http://bilketay.com/download/gan-2
I try to stream these two files through the browser like a single video file. Like;
// Dependencies
var express = require('express');
var app = express();
var CombinedStream = require('combined-stream2');
var request = require('request');
// Some routes
app.get('/', function(req, res) {
// Set header
res.set({
"Content-Type": 'video/mp4'
});
res.writeHead(200);
var combinedStream = CombinedStream.create();
// This function is to call gan-1 first, then gan-2
var recursive = function(param) {
var req = request('http://bilketay.com/download/' + param);
// First add gan-1, then gan-2
combinedStream.append(req);
req.on('end', function() {
if (param != 'gan-2') {
recursive('gan-2')
}
});
}
// Start recursive
recursive('gan-1');
// Start stream browser
// But, It does not start until it is completely loaded :(
combinedStream.pipe(res);
});
// Listen port
app.listen(3000);
I created this code with restricted node.js information. No problem for me, but I think Google Chrome is different. :)
The problem is, the two parts do not stream without being loaded. The stream starts after two parts have been uploaded. What I want to do is start the stream right away. A short note; gan-1 and gan-2 files are working locally. But it does not work on the remote server. What am I doing wrong?
I used the combined-stream2 module to merge the parts.
This module simplifies streaming by adding two different files. But because I can not get the result I want, I might have used it wrong.
In short, I want to stream two different files through the browser, respectively.
I need the help of ninjas. Thank you.
Screen shot describing the problem;
stream.gif
I've distilled my issue to some really basic functionality here. Basically, we're sending a request to a server (you can go ahead and c/p the URL and see the json document we get in response).
We get the response, we pipe it into a write stream and save it as a .json file - but the problem is that the file keeps being cut off. Is the .json file too large? Or am I missing something? Node.js newbie - massively appreciate any help I can get.
var fs = require('fs');
var url = 'https://crest-tq.eveonline.com/market/10000002/history/?type=https://crest-tq.eveonline.com/inventory/types/34/'
var request = require('request');
request(url).pipe(fs.createWriteStream('34_sell.json'));
var fs = require('fs');
var request = require('request');
var url = 'https://crest-tq.eveonline.com/market/10000002/history/?type=https://crest-tq.eveonline.com/inventory/types/34/';
request(url).pipe(fs.createWriteStream('34_sell.json'));
Not an answer but this is the code I used. I'm using request version 2.74.0. And node version v5.4.1.
Try writing a get request to the url and send the json as response and write an error handling statement like if err then throw err..console log and see the result..hope it works
I have a fully functioning PHP application that I am trying to make a Node.js version of. It deals with serving image tiles. When it's ready to display the image it does:
// Stream out the image
echo self::$tile;
How would I do something similar in Node.js? I understand this is a broad question, but I think my biggest issue is that I don't understand how PHP "echoes" an image.
Details:
I'm using AWS to get the image. The AWS call returns a Buffer. At this point of time, in the Javascript I have left the image as a Buffer.
The site populates a map with tiled images, so there are multiple calls with the image placed at a particular location on the page. I am using express to handle the requests.
app.get(/^\/omb\/1.0.0\/(.+)\/(.+)\/(.+)\/(.+)\.[a-zA-Z]*$/, function(req, res){
var MosaicStreamer = require('./models/MosaicStreamer.js');
var ms = new MosaicStreamer;
var configs = {library: req.params[0], zoom: req.params[1], column: req.params[2], row: req.params[3]};
ms.handleTile(configs);
});
handleTile grabs the image and ultimately brings me to where I am now. The image is grabbed using the following:
var aws = new AWS.S3();
var params = {
Bucket: this.bucket,
Key: this.tileDirectory + this.filepath,
Range: 'bytes=' + (this.toffset + 4) + "-" + (this.tsize + this.toffset + 4)
};
var ts = this;
aws.getObject(params, function(err, data){
if(ts.tile == null){
ts.tile = data.Body; //S3 get object
}
}
I think what you want to do is take a given URL which represents closely the naming convention of folders/files in your S3 Bucket. So assuming that you've established a client connection to your S3, you can use the readFile method. The 2nd argument is an imageStream which you can pass in the response. Once the stream has ended from S3, it will automatically end the res from the client, outputting the image directly to the client (as you intend).
Some psuedo code:
app.get(/^\/omb\/1.0.0\/(.+)\/(.+)\/(.+)\/(.+)\.[a-zA-Z]*$/, function(req, res){
var MosaicStreamer = require('./models/MosaicStreamer.js');
var ms = new MosaicStreamer;
var configs = {library: req.params[0], zoom: req.params[1], column: req.params[2], row: req.params[3]};
return ms.handleTile(configs, res);
//return the handleTile function, add 2nd argument and pass res through
});
Inside of handleTile function you can make the call for the S3
function handleTile(configs, res){
client.readFile('filename', function(error, imageStream){
imageStream.pipe(res);
});
}
Now requests to images like this:
<img src="/path/to/my/file/that/matches/regexp/expression"/>
It will request that image from the S3 Bucket and stream the resource back to the client directly.
To successfully render an image, you have to implement three steps:
Retrieve the image data (for instance as a Buffer read via fs.readFile) or a stream (for instance via fs.createReadStream
Set the appropriate headers in the web request handler with the arguments (req, res); something like
res.writeHead(200, {'Content-Type': 'image/png'});
Write the file. If you have the file in a Buffer, with
res.end(buf, 'binary');
If you have a stream via
read_stream.pipe(res)
The whole code may look like (assuming you want to serve the file image.jpg from the current directory):
'use strict';
var fs = require('fs');
var http = require('http');
http.createServer(function(req, res) {
fs.readFile('image.jpg', function(err, buf) {
if (err) {
res.writeHead(500);
res.end('Cannot access file.');
return;
}
res.writeHead(200, {'Content-Type': 'image/jpeg'});
res.end(buf, 'binary');
});
}).listen(8002, '');
Using a stream, a very simple version (beware: no error handling, with error handling it can get a little bit more complex, depending how you want to handle errors occurring while the file is being read)
'use strict';
var fs = require('fs');
var http = require('http');
http.createServer(function(req, res) {
var stream = fs.createReadStream('image.jpg');
// Error handling omitted here
res.writeHead(200, {'Content-Type': 'image/jpeg'});
stream.pipe(res);
}).listen(8003, '');
Code that uses a Buffer is easier to write, but means that your server must hold the whole file in memory - for instance, you will be unable to serve a 320 Gigapixel image file. You also only start sending data once you have the whole file.
Using a stream allows sending the file as soon as you get it, so it will be a little faster. If you're reading from file or a local fast server the speed difference is likely negligible. In addition, you'll only need a little bit of memory. On the other hand, error handling is more complex.