I'm using yargs to validate cli arguments for a data-loading helper lib.
I want to be able to check that a file exists before allowing the script to run, which I do with fs.accessSync(filename, fs.R_OK);. However, if the file does not exist, the messaging simply shows the .check() function as the error, whereas I want to intercept, and state that the file does not exist (with read permissions).
So how to I send an error to be presented by .check() on a false return?
Here is the gist of my yargs:
var path = {
name: 'filepath',
options: {
alias: 'f',
describe: 'provide json array file',
demand: true,
},
};
function fileExists(filename) {
try {
fs.accessSync(filename, fs.R_OK);
return true;
} catch (e) {
return false;
}
}
var argv = require('yargs')
.usage('$0 [args]')
.option(path.name, path.options)
.check(function (argv) {
return fileExists(argv.f);
})
.strict()
.help('help')
.argv;
and the returned error if not a readable file:
Argument check failed: function (argv) {
return fileExists(argv.f);
}
I'd prefer to be able to specify something along the lines of:
Argument check failed: filepath is not a readable file
So in yargs 5.0.0 when you return a non-truthy value it will print that entire output.
Argument check failed: function (argv) {
return fileExists(argv.f);
}
If you throw instead you can control the output message.
.check((argv) => {
if (fileExists(argv.f)) {
return true;
}
throw new Error('Argument check failed: filepath is not a readable file');
})
Related
I am trying to set up unit testing for my discord.js bot, but when running npm test in the terminal, while the test is being passed, still gives an error.
This is an image of the test being passed followed by the error:
https://i.imgur.com/m2EOuxc.png
I need to fix this error in testing, while still having the bot being able to function.
I have tried to completely remove the line referenced in the error (and the lines that had something to do with that specific line)
jsfiles.forEach((f, i) => {
let props = require(`./cmds/${f}`)
bot.commands.set(props.help.name, props)
})
Removing this resolved the testing issue, but resulted in the bot not functioning correctly (it did not load the commands; meaning, the bot couldn't be interacted with), which is not the goal here.
I've also checked, that each of the files in the folder cmds ends with
module.exports.help = {
name: '<name of the command I use for each command>'
}
This is the part of my bot.js file that contains the problem.
// Loads the commands for the bot:
fs.readdir('./cmds/', (err, files) => {
if (err) console.error(err)
let jsfiles = files.filter(f => f.split('.').pop() === 'js')
if (jsfiles.length <= 0) {
console.log('No commands to load!')
return
}
if (testingSettings) {
console.log(`Loading ${jsfiles.length} commands!`)
}
// This is the problem referenced above:
// ----------------------------------------------------------------------
jsfiles.forEach((f, i) => {
let props = require(`./cmds/${f}`)
bot.commands.set(props.help.name, props)
})
// ----------------------------------------------------------------------
})
This is all of my code in the bot.test.js file
const {
// Functions
checkingTesting,
// Variables
testingSettings,
} = require('./bot')
test('checking to see if testing-mode is on', () => {
expect(checkingTesting(testingSettings, 'token')).toBe(process.env['token']);
});
If it is needed. This is the function, variable and exporting method that is used to connect bot.js to bot.test.js:
Variable (in bot.js file)
const testingSettings = false
Function (in bot.js file)
function checkingTesting (testingSettings, name) {
if (testingSettings) {
return testSettings[name]
} else if (!testingSettings) {
return process.env[name]
}
}
Exporting (in bot.js file)
module.exports = {
// Exporting functions
checkingTesting: checkingTesting,
// Exporting variables
testingSettings: testingSettings,
}
props.help is undefined. The required file's exported obj is either empty, doesn't have help, or some other unforeseen event.
A good practice is to always check whether an object key exist prior using it.
if (props && props.help) {
bot.commands.set(props.help.name, props)
} else {
//throw or handle error here
}
In your command file, it seems like there is no help property of module.exports. When you try to read help.name, it throws your error because help is undefined.
Check to make sure that you're declaring module.exports.help in every command file.
I have a Node script that downloads a zip into tmp/archive.zip and extracts that to tmp/archive.
I would like to move the contents of tmp/archive into .. I'm having difficulty finding how to use fs.rename in a way that is equivalent to mv tmp/archive/* .
I have tried fs.rename('tmp/archive/*', '.', function(err){ but that gives me the following error: Error: ENOENT: no such file or directory, rename 'tmp/archive/*' -> '.'
I have also tried using glob to list the contents of tmp/archive and then iterate through it and move the files using fs-extra's move, as follows:
glob('tmp/archive/*', {}, function(err, files){
for (var i = files.length - 1; i >= 0; i--) {
fs.move(files[i], '.', function(err){});
}
}.bind(this));
which results in the folowing error: Error: EEXIST: file already exists, link 'tmp/archive/subdirectory' -> '.'
I could just call mv tmp/archive/* . from the script but i would like to avoid that if possible. Is there something obvious I am missing? How can I go about doing this?
Here's one way to move a directory of files from one location to another (assuming they are on the same volume and thus can be renamed rather than copied):
var Promise = require('bluebird');
var fs = Promise.promisifyAll(require('fs'));
var path = require('path');
function moveFiles(srcDir, destDir) {
return fs.readdirAsync(srcDir).map(function(file) {
var destFile = path.join(destDir, file);
console.log(destFile);
return fs.renameAsync(path.join(srcDir, file), destFile).then(function() {
return destFile;
});
});
}
// sample usage:
moveFiles(path.join(".", "tempSource"), path.join(".", "tempDest")).then(function(files) {
// all done here
}).catch(function(err) {
// error here
});
This will move both files and sub-directories in the srcDir to destDir. Since fs.rename() will move a sub-directory all at once, you don't have to traverse recursively.
When designing a function like this, you have a choice of error behavior. The above implementation aborts upon the first error. You could change the implementation to move all files possible and then just return a list of files that could not be moved.
Here's a version that renames all files that it can and if there were any errors, it rejects at the end with a list of the files that failed and their error objects:
function moveFilesAll(srcDir, destDir) {
return fs.readdirAsync(srcDir).map(function(file) {
var destFile = path.join(destDir, file);
var srcFile = path.join(srcDir, file);
return fs.renameAsync(srcFile, destFile).then(function() {
return {file: srcFile, err: 0};
}).catch(function(err) {
console.log("error on " + srcFile);
return {file: srcFile, err: err}
});
}).then(function(files) {
var errors = files.filter(function(item) {
return item.err !== 0;
});
if (errors.length > 0) {
// reject with a list of error files and their corresponding errors
throw errors;
}
// for success, return list of all files moved
return files.filter(function(item) {
return item.file;
});
});
}
// sample usage:
moveFilesAll(path.join(".", "tempSource"), path.join(".", "tempDest")).then(function(files) {
// all done here
}).catch(function(errors) {
// list of errors here
});
I'm loading a config.json file using require('./config.json') but I don't want to require a config file if they want to pass command line arguments instead, or just use the defaults. Is there any way to try to load a JSON file this way but not spit out an error if it can't be found?
For general modules, you can check for existence before trying to load. In the following path is whatever path you want to load and process() is a function performing whatever processing you'd like on your module:
var fs = require("fs");
fs.exists(path, function (exists) {
if (exists) {
var foo = require(path);
process(foo);
}
else {
// Whatever needs to be done if it does not exist.
}
});
And remember that path above must be an actual path, and not a module name to be later resolved by Node as a path.
For a JSON file specifically, with path and process having the same meanings as above:
fs.readFile(path, function (err, data) {
if (err) {
// Whatever you must do if the file cannot be read.
return;
}
var parsed = JSON.parse(data);
process(parsed);
});
You can also use try... catch but keep in mind that v8 won't optimize functions that have try... catch in them. With path and process meaning the same as above:
try {
var foo = require(path);
process(foo);
}
catch (e) {
if (e.code !== "MODULE_NOT_FOUND")
throw e; // Other problem, rethrow.
// Do what you need if the module does not exist.
}
I am trying to modify require like this
require = function (path) {
try {
return module.require(path);
} catch (err) {
console.log(path)
}
}
However, scope of this modification is only in the current module. I want to modify it globally, so every module that is required by this module will also get the same copy of require function.
Basically, I want to catch SyntaxError to know which file has problem. I can't seem to find any other alternative. If I put module.require in try/catch block, I'll be able to get the file name which caused SyntaxError.
I managed to solve it by modifying prototype function require of Module class. I put this in the main script and its available to all the required modules.
var pathModule = require('path');
var assert = require('assert').ok;
module.constructor.prototype.require = function (path) {
var self = this;
assert(typeof path === 'string', 'path must be a string');
assert(path, 'missing path');
try {
return self.constructor._load(path, self);
} catch (err) {
// if module not found, we have nothing to do, simply throw it back.
if (err.code === 'MODULE_NOT_FOUND') {
throw err;
}
// resolve the path to get absolute path
path = pathModule.resolve(__dirname, path)
// Write to log or whatever
console.log('Error in file: ' + path);
}
}
Why don't you use a try-catch block inside your code and once an error occurs to check the stack trace. Check out these links
How to print a stack trace in Node.js?
http://machadogj.com/2013/4/error-handling-in-nodejs.html
I can't seem to get any search results that explain how to do this.
All I want to do is be able to know if a given path is a file or a directory (folder).
The following should tell you. From the docs:
fs.lstatSync(path_string).isDirectory()
Objects returned from fs.stat() and fs.lstat() are of this type.
stats.isFile()
stats.isDirectory()
stats.isBlockDevice()
stats.isCharacterDevice()
stats.isSymbolicLink() // (only valid with fs.lstat())
stats.isFIFO()
stats.isSocket()
NOTE:
The above solution will throw an Error if; for ex, the file or directory doesn't exist.
If you want a true or false approach, try fs.existsSync(dirPath) && fs.lstatSync(dirPath).isDirectory(); as mentioned by Joseph in the comments below.
Update: Node.Js >= 10
We can use the new fs.promises API
const fs = require('fs').promises;
(async() => {
const stat = await fs.lstat('test.txt');
console.log(stat.isFile());
})().catch(console.error)
Any Node.Js version
Here's how you would detect if a path is a file or a directory asynchronously, which is the recommended approach in node.
using fs.lstat
const fs = require("fs");
let path = "/path/to/something";
fs.lstat(path, (err, stats) => {
if(err)
return console.log(err); //Handle error
console.log(`Is file: ${stats.isFile()}`);
console.log(`Is directory: ${stats.isDirectory()}`);
console.log(`Is symbolic link: ${stats.isSymbolicLink()}`);
console.log(`Is FIFO: ${stats.isFIFO()}`);
console.log(`Is socket: ${stats.isSocket()}`);
console.log(`Is character device: ${stats.isCharacterDevice()}`);
console.log(`Is block device: ${stats.isBlockDevice()}`);
});
Note when using the synchronous API:
When using the synchronous form any exceptions are immediately thrown.
You can use try/catch to handle exceptions or allow them to bubble up.
try{
fs.lstatSync("/some/path").isDirectory()
}catch(e){
// Handle error
if(e.code == 'ENOENT'){
//no such file or directory
//do something
}else {
//do something else
}
}
Seriously, question exists five years and no nice facade?
function isDir(path) {
try {
var stat = fs.lstatSync(path);
return stat.isDirectory();
} catch (e) {
// lstatSync throws an error if path doesn't exist
return false;
}
}
Depending on your needs, you can probably rely on node's path module.
You may not be able to hit the filesystem (e.g. the file hasn't been created yet) and tbh you probably want to avoid hitting the filesystem unless you really need the extra validation. If you can make the assumption that what you are checking for follows .<extname> format, just look at the name.
Obviously if you are looking for a file without an extname you will need to hit the filesystem to be sure. But keep it simple until you need more complicated.
const path = require('path');
function isFile(pathItem) {
return !!path.extname(pathItem);
}
If you need this when iterating over a directory (Because that's how I've found this question):
Since Node 10.10+, fs.readdir has a withFileTypes option which makes it return directory entry fs.Dirent instead of strings. Directory entries has a name property, and useful methods such as isDirectory or isFile, so you don't need to call fs.lstat explicitly.
import { promises as fs } from 'fs';
// ./my-dir has two subdirectories: dir-a, and dir-b
const dirEntries = await fs.readdir('./my-dir', { withFileTypes: true });
// let's filter all directories in ./my-dir
const onlyDirs = dirEntries.filter(de => de.isDirectory()).map(de => de.name);
// onlyDirs is now [ 'dir-a', 'dir-b' ]
Here's a function that I use. Nobody is making use of promisify and await/async feature in this post so I thought I would share.
const promisify = require('util').promisify;
const lstat = promisify(require('fs').lstat);
async function isDirectory (path) {
try {
return (await lstat(path)).isDirectory();
}
catch (e) {
return false;
}
}
Note : I don't use require('fs').promises; because it has been experimental for one year now, better not rely on it.
The answers above check if a filesystem contains a path that is a file or directory. But it doesn't identify if a given path alone is a file or directory.
The answer is to identify directory-based paths using "/." like --> "/c/dos/run/." <-- trailing period.
Like a path of a directory or file that has not been written yet. Or a path from a different computer. Or a path where both a file and directory of the same name exists.
// /tmp/
// |- dozen.path
// |- dozen.path/.
// |- eggs.txt
//
// "/tmp/dozen.path" !== "/tmp/dozen.path/"
//
// Very few fs allow this. But still. Don't trust the filesystem alone!
// Converts the non-standard "path-ends-in-slash" to the standard "path-is-identified-by current "." or previous ".." directory symbol.
function tryGetPath(pathItem) {
const isPosix = pathItem.includes("/");
if ((isPosix && pathItem.endsWith("/")) ||
(!isPosix && pathItem.endsWith("\\"))) {
pathItem = pathItem + ".";
}
return pathItem;
}
// If a path ends with a current directory identifier, it is a path! /c/dos/run/. and c:\dos\run\.
function isDirectory(pathItem) {
const isPosix = pathItem.includes("/");
if (pathItem === "." || pathItem ==- "..") {
pathItem = (isPosix ? "./" : ".\\") + pathItem;
}
return (isPosix ? pathItem.endsWith("/.") || pathItem.endsWith("/..") : pathItem.endsWith("\\.") || pathItem.endsWith("\\.."));
}
// If a path is not a directory, and it isn't empty, it must be a file
function isFile(pathItem) {
if (pathItem === "") {
return false;
}
return !isDirectory(pathItem);
}
Node version: v11.10.0 - Feb 2019
Last thought: Why even hit the filesystem?
I could check if a directory or file exists using this:
// This returns if the file is not a directory.
if(fs.lstatSync(dir).isDirectory() == false) return;
// This returns if the folder is not a file.
if(fs.lstatSync(dir).isFile() == false) return;
Function that returns type
I like coffee
type: (uri)-> (fina) ->
fs.lstat uri, (erro,stats) ->
console.log {erro} if erro
fina(
stats.isDirectory() and "directory" or
stats.isFile() and "document" or
stats.isSymbolicLink() and "link" or
stats.isSocket() and "socket" or
stats.isBlockDevice() and "block" or
stats.isCharacterDevice() and "character" or
stats.isFIFO() and "fifo"
)
usage:
dozo.type("<path>") (type) ->
console.log "type is #{type}"