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.
Related
I am going back to learning js after many years off and all i want to do is read the contents of a file onto the console using Nodejs. I found the sample code. Nice and simple. I have spent over an hour trying to figure out why it will not find the file. This is sample right off the documentation and i made it exactly like the example to debug it. The absolute only difference is the name joe is replaced with my user folder.
const fs = require('fs')
fs.readFile('/Users/gendi/test.txt', 'utf8' , (err, data) => {
if (err) {
console.error(err)
return
}
console.log(data)
})
It runs fine except it will not find test.text. no matter what. I receive the following error and no matter how i format the file path. Nothing.
C:\Users\gendi>node readfile.js
[Error: ENOENT: no such file or directory, open 'C:\Users\gendi\test.txt'] {
errno: -4058,
code: 'ENOENT',
syscall: 'open',
path: 'C:\\Users\\gendi\\pcsSnipe\\test.txt'
}
You can also only pass in the file path as 'test.txt' and the exact same results come up. on the first part of the error msg the path looks formatted correctly but on the last line of the error msg it is not? Its been years.. so i know i am missing something really simple. I assure that file is there!! Thank you in advance and forgive my ineptness.
The fs module requires an exact path to the file you'd like to read. A simple fix to this would be to add __dirname which will return the directory path along with the path of your file.
// Define modules
const fs = require('fs');
const path = require('path');
// Read the file
fs.readFile(path.join(__dirname, '/Users/gendi/test.txt'), 'utf8' , (err, data) => {
if (err) // If FS returned an error
return console.error(err); // Log the error and return
console.log(data); // If the reading was successful, log the data
});
It works if you remove the file extention, '.txt' . Idk why it make a differnce. maybe the "." is throwing it off but it doesn't matter in this respect. Thank you
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 have a very simple node lambda function which reads the contents of packaged file in it. I upload the code as zip file. The directory structure is as follows.
index.js
readme.txt
Then have in my index.js file:
fs.readFile('/var/task/readme.txt', function (err, data) {
if (err) throw err;
});
I keep getting the following error NOENT: no such file or directory, open '/var/task/readme.txt'.
I tried ./readme.txt also.
What am I missing ?
Try this, it works for me:
'use strict'
let fs = require("fs");
let path = require("path");
exports.handler = (event, context, callback) => {
// To debug your problem
console.log(path.resolve("./readme.txt"));
// Solution is to use absolute path using `__dirname`
fs.readFile(__dirname +'/readme.txt', function (err, data) {
if (err) throw err;
});
};
to debug why your code is not working, add below link in your handler
console.log(path.resolve("./readme.txt"));
On AWS Lambda node process might be running from some other folder and it looks for readme.txt file from that folder as you have provided relative path, solution is to use absolute path.
What worked for me was the comment by Vadorrequest to use process.env.LAMBDA_TASK_ROOT. I wrote a function to get a template file in a /templates directory when I'm running it locally on my machine with __dirname or with the process.env.LAMBDA_TASK_ROOT variable when running on Lambda:
function loadTemplateFile(templateName) {
const fileName = `./templates/${templateName}`
let resolved
if (process.env.LAMBDA_TASK_ROOT) {
resolved = path.resolve(process.env.LAMBDA_TASK_ROOT, fileName)
} else {
resolved = path.resolve(__dirname, fileName)
}
console.log(`Loading template at: ${resolved}`)
try {
const data = fs.readFileSync(resolved, 'utf8')
return data
} catch (error) {
const message = `Could not load template at: ${resolved}, error: ${JSON.stringify(error, null, 2)}`
console.error(message)
throw new Error(message)
}
}
This is an oldish question but comes up first when attempting to sort out whats going on with file paths on Lambda.
Additional Steps for Serverless Framework
For anyone using Serverless framework to deploy (which probably uses webpack to build) you will also need to add the following to your webpack config file (just after target: node):
// assume target: 'node', is here
node: {
__dirname: false,
},
Without this piece using __dirname with Serverless will STILL not get you the desired absolute directory path.
I went through this using serverless framework and it really was the file that was not sent in the compression. Just add the following line in serverless.yml:
package:
individually: false
include:
- src/**
const filepath = path.resolve('../../filename.text');
const fileData2 = fs.readFileSync(process.env.LAMBDA_TASK_ROOT + filepath, 'utf-8');
I was using fs.promises.readFile(). Couldn't get it to error out at out. The file was there, and LAMBDA_TASK_ROOT seemed right to me as well. After I changed to fs.readFileSync(), it worked.
I hade the same problem and I tried applying all these wonderful solutions above - which didn't work.
The problem was that I setup one of the folder name with one letter in upper case which was really lowercase.
So when I tried to fetch the content of /src/SOmething/some_file.txt
While the folder was really /src/Something/ - I got this error...
Windows (local environment) is case insensitive while AWS is not!!!....
I'm developing my first node webkit app. I'm confused about packing the files. Is the end product a single file that can be executed ?
The end result will not be a single executable, you must also include some DLLs in your zip-file.
These line in github made me more confused.
How is the packaging done ?
Do I need to include the webkit files also in the package or just the files I have created ?
I packaged my node-webkit app successfully for various platforms by using the below gulp script. Below is the script which is self explanatory.
Reference : https://github.com/nwjs/nwbuilder/blob/master/example/Gulpfile.js
var NwBuilder = require('nw-builder');
var gulp = require('gulp');
var gutil = require('gulp-util');
gulp.task('nw', function () {
var nw = new NwBuilder({
version: '0.12.3',
files: '../nodepoc/**',
platforms: ['osx64','win32','win64']
});
// Log stuff you want
nw.on('log', function (msg) {
gutil.log('nw-builder', msg);
});
// Build returns a promise, return it so the task isn't called in parallel
return nw.build().catch(function (err) {
gutil.log('nw-builder', err);
});
});
gulp.task('default', ['nw']);
Save the file as gulpFile.js. In terminal , simply run gulp command in the same location as that of the gulpFile.js and it will download the necessary node-webkit distributions for the platforms and build the package for you.
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.