I do not know if this is possible, but here goes. And working with callbacks makes it even more difficult.
I have a directory with html files that I want to send back to the client in Object chunks with node.js and socket.io.
All my files are in /tmpl
So socket needs to read all the files in /tmpl.
for each file it has to store the data in an object with the filename as the key, and the content as the value.
var data;
// this is wrong because it has to loop trough all files.
fs.readFile(__dirname + '/tmpl/filename.html', 'utf8', function(err, html){
if(err) throw err;
//filename must be without .html at the end
data['filename'] = html;
});
socket.emit('init', {data: data});
The final callback is also wrong. It has to be called when all the files in the directory are done.
But I do not know how to create the code, anyone know if this is possibel?
This question is related to
node.js
If you have Node.js 8 or later, you can use the new util.promisify. (I'm marking as optional the parts of the code that have to do with reformatting as an object, which the original post requested.)
const fs = require('fs');
const { promisify } = require('util');
let files; // optional
promisify(fs.readdir)(directory).then((filenames) => {
files = filenames; // optional
return Promise.all(filenames.map((filename) => {
return promisify(fs.readFile)(directory + filename, {encoding: 'utf8'});
}));
}).then((strArr) => {
// optional:
const data = {};
strArr.forEach((str, i) => {
data[files[i]] = str;
});
// send data here
}).catch((err) => {
console.log(err);
});
I just wrote this and it looks more clean to me:
const fs = require('fs');
const util = require('util');
const readdir = util.promisify(fs.readdir);
const readFile = util.promisify(fs.readFile);
const readFiles = async dirname => {
try {
const filenames = await readdir(dirname);
console.log({ filenames });
const files_promise = filenames.map(filename => {
return readFile(dirname + filename, 'utf-8');
});
const response = await Promise.all(files_promise);
//console.log({ response })
//return response
return filenames.reduce((accumlater, filename, currentIndex) => {
const content = response[currentIndex];
accumlater[filename] = {
content,
};
return accumlater;
}, {});
} catch (error) {
console.error(error);
}
};
const main = async () => {
const response = await readFiles(
'./folder-name',
);
console.log({ response });
};You can modify the response format according to your need.
The response format from this code will look like:
{
"filename-01":{
"content":"This is the sample content of the file"
},
"filename-02":{
"content":"This is the sample content of the file"
}
}
const { promisify } = require("util")
const directory = path.join(__dirname, "/tmpl")
const pathnames = promisify(fs.readdir)(directory)
try {
async function emitData(directory) {
let filenames = await pathnames
var ob = {}
const data = filenames.map(async function(filename, i) {
if (filename.includes(".")) {
var storedFile = promisify(fs.readFile)(directory + `\\${filename}`, {
encoding: "utf8",
})
ob[filename.replace(".js", "")] = await storedFile
socket.emit("init", { data: ob })
}
return ob
})
}
emitData(directory)
} catch (err) {
console.log(err)
}
Who wants to try with generators?
For all example below you need to import fs and path modules:
const fs = require('fs');
const path = require('path');
function readFiles(dir, processFile) {
// read directory
fs.readdir(dir, (error, fileNames) => {
if (error) throw error;
fileNames.forEach(filename => {
// get current file name
const name = path.parse(filename).name;
// get current file extension
const ext = path.parse(filename).ext;
// get current file path
const filepath = path.resolve(dir, filename);
// get information about the file
fs.stat(filepath, function(error, stat) {
if (error) throw error;
// check if the current path is a file or a folder
const isFile = stat.isFile();
// exclude folders
if (isFile) {
// callback, do something with the file
processFile(filepath, name, ext, stat);
}
});
});
});
}
Usage:
// use an absolute path to the folder where files are located
readFiles('absolute/path/to/directory/', (filepath, name, ext, stat) => {
console.log('file path:', filepath);
console.log('file name:', name);
console.log('file extension:', ext);
console.log('file information:', stat);
});
/**
* @description Read files synchronously from a folder, with natural sorting
* @param {String} dir Absolute path to directory
* @returns {Object[]} List of object, each object represent a file
* structured like so: `{ filepath, name, ext, stat }`
*/
function readFilesSync(dir) {
const files = [];
fs.readdirSync(dir).forEach(filename => {
const name = path.parse(filename).name;
const ext = path.parse(filename).ext;
const filepath = path.resolve(dir, filename);
const stat = fs.statSync(filepath);
const isFile = stat.isFile();
if (isFile) files.push({ filepath, name, ext, stat });
});
files.sort((a, b) => {
// natural sort alphanumeric strings
// https://stackoverflow.com/a/38641281
return a.name.localeCompare(b.name, undefined, { numeric: true, sensitivity: 'base' });
});
return files;
}
Usage:
// return an array list of objects
// each object represent a file
const files = readFilesSync('absolute/path/to/directory/');
More info on promisify in this article.
const { promisify } = require('util');
const readdir_promise = promisify(fs.readdir);
const stat_promise = promisify(fs.stat);
function readFilesAsync(dir) {
return readdir_promise(dir, { encoding: 'utf8' })
.then(filenames => {
const files = getFiles(dir, filenames);
return Promise.all(files);
})
.catch(err => console.error(err));
}
function getFiles(dir, filenames) {
return filenames.map(filename => {
const name = path.parse(filename).name;
const ext = path.parse(filename).ext;
const filepath = path.resolve(dir, filename);
return stat({ name, ext, filepath });
});
}
function stat({ name, ext, filepath }) {
return stat_promise(filepath)
.then(stat => {
const isFile = stat.isFile();
if (isFile) return { name, ext, filepath, stat };
})
.catch(err => console.error(err));
}
Usage:
readFiles('absolute/path/to/directory/')
// return an array list of objects
// each object is a file
// with those properties: { name, ext, filepath, stat }
.then(files => console.log(files))
.catch(err => console.log(err));
Note: return undefined for folders, if you want you can filter them out:
readFiles('absolute/path/to/directory/')
.then(files => files.filter(file => file !== undefined))
.catch(err => console.log(err));
Are you a lazy person like me and love npm module :D then check this out.
npm install node-dir
example for reading files:
var dir = require('node-dir');
dir.readFiles(__dirname,
function(err, content, next) {
if (err) throw err;
console.log('content:', content); // get content of files
next();
},
function(err, files){
if (err) throw err;
console.log('finished reading files:', files); // get filepath
});
For the code to work smoothy in different enviroments, path.resolve can be used in places where path is manipulated. Here is code which works better.
Reading part:
var fs = require('fs');
function readFiles(dirname, onFileContent, onError) {
fs.readdir(dirname, function(err, filenames) {
if (err) {
onError(err);
return;
}
filenames.forEach(function(filename) {
fs.readFile(path.resolve(dirname, filename), 'utf-8', function(err, content) {
if (err) {
onError(err);
return;
}
onFileContent(filename, content);
});
});
});
}
Storing part:
var data = {};
readFiles(path.resolve(__dirname, 'dirname/'), function(filename, content) {
data[filename] = content;
}, function(error) {
throw err;
});
Another version with Promise's modern method. It's shorter that the others responses based on Promise :
const readFiles = (dirname) => {
const readDirPr = new Promise( (resolve, reject) => {
fs.readdir(dirname,
(err, filenames) => (err) ? reject(err) : resolve(filenames))
});
return readDirPr.then( filenames => Promise.all(filenames.map((filename) => {
return new Promise ( (resolve, reject) => {
fs.readFile(dirname + filename, 'utf-8',
(err, content) => (err) ? reject(err) : resolve(content));
})
})).catch( error => Promise.reject(error)))
};
readFiles(sourceFolder)
.then( allContents => {
// handle success treatment
}, error => console.log(error));
This is a modern Promise version of the previous one, using a Promise.all approach to resolve all promises when all files have been read:
/**
* Promise all
* @author Loreto Parisi (loretoparisi at gmail dot com)
*/
function promiseAllP(items, block) {
var promises = [];
items.forEach(function(item,index) {
promises.push( function(item,i) {
return new Promise(function(resolve, reject) {
return block.apply(this,[item,index,resolve,reject]);
});
}(item,index))
});
return Promise.all(promises);
} //promiseAll
/**
* read files
* @param dirname string
* @return Promise
* @author Loreto Parisi (loretoparisi at gmail dot com)
* @see http://stackoverflow.com/questions/10049557/reading-all-files-in-a-directory-store-them-in-objects-and-send-the-object
*/
function readFiles(dirname) {
return new Promise((resolve, reject) => {
fs.readdir(dirname, function(err, filenames) {
if (err) return reject(err);
promiseAllP(filenames,
(filename,index,resolve,reject) => {
fs.readFile(path.resolve(dirname, filename), 'utf-8', function(err, content) {
if (err) return reject(err);
return resolve({filename: filename, contents: content});
});
})
.then(results => {
return resolve(results);
})
.catch(error => {
return reject(error);
});
});
});
}
How to Use It:
Just as simple as doing:
readFiles( EMAIL_ROOT + '/' + folder)
.then(files => {
console.log( "loaded ", files.length );
files.forEach( (item, index) => {
console.log( "item",index, "size ", item.contents.length);
});
})
.catch( error => {
console.log( error );
});
Supposed that you have another list of folders you can as well iterate over this list, since the internal promise.all will resolve each of then asynchronously:
var folders=['spam','ham'];
folders.forEach( folder => {
readFiles( EMAIL_ROOT + '/' + folder)
.then(files => {
console.log( "loaded ", files.length );
files.forEach( (item, index) => {
console.log( "item",index, "size ", item.contents.length);
});
})
.catch( error => {
console.log( error );
});
});
How it Works
The promiseAll does the magic. It takes a function block of signature function(item,index,resolve,reject), where item is the current item in the array, index its position in the array, and resolve and reject the Promise callback functions.
Each promise will be pushed in a array at the current index and with the current item as arguments through a anonymous function call:
promises.push( function(item,i) {
return new Promise(function(resolve, reject) {
return block.apply(this,[item,index,resolve,reject]);
});
}(item,index))
Then all promises will be resolved:
return Promise.all(promises);
Source: Stackoverflow.com