I am using NodeJS on heroku.
I read a file from another server and save it into my application in the /temp directory.
Next, I read the same file to pass it on to my client.
The code that saves the file and then subsequently reads it is:
http.request(options, function (pdfResponse) {
var filename = Math.random().toString(36).slice(2) + '.pdf',
filepath = nodePath.join(process.cwd(),'temp/' + filename);
pdfResponse.on('end', function () {
fs.readFile(filepath, function (err, contents) {
//Stuff to do after reading
});
});
//Read the response and save it directly into a file
pdfResponse.pipe(fs.createWriteStream(filepath));
});
This works well on my localhost.
However, when deployed to heroku, I get the following error:
events.js:72
throw er; // Unhandled 'error' event
Error: ENOENT, open '/app/temp/nvks0626yjf0qkt9.pdf'
Process exited with status 8
State changed from up to crashed
I am using process.cwd() to ensure that the path is correctly used. But even then it did not help. As per the heroku documentation, I am free to create files in the applications directory, which I am doing. But I can't figure out why this is failing to read the file...
The error you describe there is consistent with /app/temp/ not existing. You need to create it before you start writing in it. The idea is:
var fs = require("fs");
var path = require("path");
var temp_dir = path.join(process.cwd(), 'temp/');
if (!fs.existsSync(temp_dir))
fs.mkdirSync(temp_dir);
I've used the sync version of the calls for illustrations purposes only. This code should be part of the start up code for your app (instead of being called for each request) and how you should structure it depends on your specific application.
Related
I am trying to write a file in node.js using fs.writeFile, I use the following code:
const fs = require('filer');
const jsonString = JSON.stringify(myObj)
fs.writeFile('/myFile.txt', jsonString, function (err) {
if (err) throw err;
console.log('Saved!');
});
}
I am sure the file is created, because I can read it by fs.readFile referring to the same address, but I cannot find it on the disk by using windows search. What I understood, if I change the localhost port it saves the files in another location. I already tried "process.cwd()", but it didn't work.
I really appreciate it if someone could help.
try to use : __dirname instead of process.cwd()
const fs = require('fs');
const path = require('path');
const filePath = path.join(__dirname, '/myFile.txt');
console.log(filePath);
const jsonString = JSON.stringify({ name: "kalo" })
fs.writeFile(filePath, jsonString, (err) => {
if (err) throw err;
console.log('The file has been saved!');
});
And I would like to know why are you using 'filer' instead of default fs module?
fs module is native module that provides file handling in node js. so you don't need to install it specifically. This code perfectly worked and it prints absolute location of the file as well.Just run this code if it doesn't work, I think you should re install node js. I have updated the answer.You can also use fs.writeFileSync method as well.
From documentation: "String form paths are interpreted as UTF-8 character sequences identifying the absolute or relative filename. Relative paths will be resolved relative to the current working directory as determined by calling process.cwd()."
So in order to determine your working directory (i.e. where fs create files by default) call (works for me):
console.log(process.cwd());
Then if you would like to change your working directory, you can call (works for me as well):
process.chdir('path_to_new_directory');
Path can be relative or absolute.
This is also from documentation: "The process.chdir() method changes the current working directory of the Node.js process or throws an exception if doing so fails (for instance, if the specified directory does not exist)."
I had to create a directory named stuff and write the stream into a text file inside the "stuff" directory. but, because the code in NodeJs doesn't execute in a serial fashion, I m getting an error which says the directory doesn't exist. any help would be appreciated. the code is pasted below.
var http = require("http");
var fs = require("fs");
var readStream = fs.createReadStream(__dirname+"/readMe.txt","UTF-8");
var writeStream;
fs.mkdir("stuff",function(){
writeStream = fs.createWriteStream(__dirname+"/stuff/writeMe.txt");
});
readStream.on("data",function(chunk){
writeStream.write(chunk);
});
When you call the folder creation function, it returns instantly. But the callback function is executed only when the folder has been created (or creation has failed.)
fs.mkdir("stuff",function(){
// executed after folder creation
writeStream = fs.createWriteStream(__dirname+"/stuff/writeMe.txt");
});
// executed instantly
In your current code, when you try to write to the folder, it has not been created yet, and writeStream is undefined.
So you need to write to the folder after it's been created:
fs.mkdir("stuff",function(){
writeStream = fs.createWriteStream(__dirname+"/stuff/writeMe.txt");
readStream.on("data",function(chunk){
writeStream.write(chunk);
});
});
I'm trying to download files to the filesystem in an electron app. My code, in the main thread, looks like this:
const dir = `${__dirname}/media`;
if (!fs.existsSync(dir)){
fs.mkdirSync(dir);
}
const file = fs.createWriteStream(`${dir}/${name}`);
file.on("open", function() {
const request = http.get(url, function(response) {
response.pipe(file);
response.on('end', function() {
file.close();
...
});
});
request.on('error', function(err) {
...
});
});
This works when running in development using electron . But after I build it with electron-builder, I get the error in an alert:
Uncaught Exception:
Error: ENOENT, media/uploads_2016_02_BASF_Holistic_Program.jpg not found in /Users/nicholasstephan/Desktop/XXXXXXX/dist/Mac/XXXXXX.app/Contents/Resources/app.asar
at notFoundError (ELECTRON_ASAR.js:109:19)
at Object.module.(anonymous function) [as open] (ELECTRON_ASAR.js:209:16)
at WriteStream.open (fs.js:1890:6)
at new WriteStream (fs.js:1876:10)
at Object.fs.createWriteStream (fs.js:1831:10)
at next (/Users/nicholasstephan/Desktop/XXXXXXXX/dist/Mac/XXXXXXXX.app/Contents/Resources/app.asar/media.js:19:18)
at /Users/nicholasstephan/Desktop/XXXXXXXX/dist/Mac/XXXXXXXX.app/Contents/Resources/app.asar/media.js:52:4
...
where the media.js, ln 19, being referred to is the const file = fs.createWriteStream(${dir}/${name}); line in the code.
I've tried the solutions offered in about a dozen other similar stackoverflow answers, but none have fixed the problem.
What's going on here?
Thanks.
The built Electron app uses the Asar format. Asar is an archive format (it's really just one big file) though in Electron you are able to read from it as if it were a standard directory.
I presume (though I have not seen it explicitly documented) that it is not possible to write to an Asar with the fs functions. In any case there are almost certainly more appropriate locations to write data.
Try writing to a different path. Electron provides a number of useful paths using app.getPath(name) so you could for example write to the userData directory which holds configuration files for your app.
I have this code:
var file = fs.createWriteStream(_filename, _saveFile);
var request = http.request(options);
var decrypt = Crypto.createDecipheriv('aes-128-cbc', key, iv);
var _saveFile = function(response) {
res.pipe(decrypt).pipe(file);
res.on("end", function() {
file.close();
});
};
file.on("error", function(err) {
console.log("Error while writing file", err);
});
It works ok. But randomly I'm receiving this error:
{ [Error: EBADF, write] errno: 9, code: 'EBADF' }
I read this is because the file is being written after it was closed. So, the question I have is: Am I doing something wrong? Is there any way to do decrypt.on("end")instead of res.on("end")?
MORE INFORMATION
In the same res.on("end") I have a q.defer().resolve call, because this method is downloading several .ts files and then I need to turn them into a MP4.
As #mscdex said, there is no need to close the file, however, if the promise is resolved before the file has been actually finished then, I may be working with a corrupted file. Like this:
Download 1.ts
Download 2.ts
Download 3.ts
Here all the promises are saved in a an array and then I use q.spread to wait for all of them
File 1.ts writted
File 1.ts resolve promise
File 2.ts writted
File 2.ts resolve promise
File 3.ts resolve promise
q.spread knows all the promises were resolved so it starts working with the .ts files
File 3.ts writted
From this point on, I'll be working with a wrong/incomplete file.
You don't need to explicitly call file.close() since the file stream will be closed automatically when upstream ends.
If you need to wait until the file is completely written, listen for the finish event on file:
file.on('finish', function() {
// resolve promise or do whatever
});
I am trying to save project and its file in GridFS. I want to save project first and using "_id" of project as metadata for file I want to save file. When i tried so i am getting ENOENT, open '/tmp/45e85388793de' error. here is my code
newProject.save(function (err,project) {
if (err) {
console.log('save error', err);
}
console.log("project added");
var id=poject._id;
var filepath = req.files.file.path;
var filename = req.files.file.name;
var writestream = gfs.createWriteStream({ filename: filename, metadata:id });
console.log(filepath);
fs.createReadStream(filepath)
.on('end', function() {
})
.on('error', function(err) {
console.log("error encountered"+err);//ENOENT,open error
})
.pipe(writestream);
});
Why i am getting this error and how to resolve it?
ENOENT in this context means "No such file or directory." It means the filepath you are trying to read with createReadStream does not exist.
I think you are getting this error since :
Your file is saved in a temporary location.
When you are inside the callback function your file is removed from that location and you are getting "No such file" error. Path and other variables still exists as part of js and that's why you are able to print them in console.
Solution:
Above(Outside) callback function move your file to some other permanent location using:
fs.rename(req.files.file.path, "./someKnownPath/filename");
Keep note of that location. In your callback function use the new location as path and try saving the file in gridfs. Once the file is saved you may delete it file from that location(/someKnownPath/filename).
This error was occuring for me as well. And the reason was temp directory was not in place. After I created manually and gave a try, it worked.
Now I have shifted to creating directory on the fly through node.js itself.