i have come across a strange error in nodejs filesystem - node.js

Question

i am working with the filesystem protocol of nodejs. i did writing the file, reading the file and now trying to rename it. it actually renames the file but throws me this error and my localhost stops running.
this is the error:
_http_outgoing.js:690
throw new ERR_INVALID_ARG_TYPE('chunk', ['string', 'Buffer'], chunk);
TypeError [ERR_INVALID_ARG_TYPE]: The "chunk" argument must be one of type string or Buffer. Received type object
file1: var fs = require('fs');
// write
function write(fileName, content) {
return new Promise(function (resolve, reject) {
fs.writeFile(`./test/${fileName}`, content, function (err, done) {
if (err) {
reject(err);
return;
}
resolve(done);
// console.log('file created >>', done);
});
})
}
function readFile(fileName, cb) {
fs.readFile(`./test/${fileName}`, 'utf-8', function (err, done) {
if (err) {
cb(err);
return;
}
cb(null, done);
})
}
function rename(oldname, newname, cb){
fs.rename(`./bands/${oldname}`, `./bands/${newname}`, function(err,done){
if(err){
cb(err)
return
}
cb(null,done)
})
}
rename('pinkfloyd.txt', 'tool.txt', function(err, done){
if(err){
console.log('error in renaming')
}
else{
console.log('renamed>>')
}
})
readFile('kisor.txt', function(err,done){
if(err){
console.log("error in file reading >>",err);
}else{
console.log('success >>',done);
}
})
write('kisor.txt', 'i am javascript')
.then(function (data) {
console.log('write success ', data);
})
.catch(function (err) {
console.log('error in wirte >>', err);
})
// objec short hand
module.exports = {
write, readFile, rename
}
i have imported the exported stuff from file 1 here in this file:
//var { write,readFile, } = require('./file');// object destruct
var fileOp = require('./file1');
//console.log('file operation >>', fileOp);
fileOp.write('brodway.txt', 'i am infosys of nepal')
.then(function (data) {
console.log('done >>>', data);
})
.catch(function(err){
console.log('err',err);
})
fileOp.readFile('kisor.txt',function(err,done){
if(err){
console.log('err',err);
}else{
console.log('success >>',done);
}
and lastly, here is the server:
var http = require('http');
var fileOp = require('./file1');
var server = http.createServer(function (request, response) {
// this function will be executed whenever a client is connected
// request or 1st argument is http request object
// response or 2nd argument is http response object
var url = request.url;
if (url == '/write') {
fileOp.write('abcd.js', 'hi')
.then(function (data) {
response.end('data', data);
})
.catch(function (err) {
response.end(err);
})
} else if (url == '/read') {
fileOp.readFile('abcd.js', function (err, done) {
if (err) {
response.end(err);
} else {
response.end('done' + done);
}
})
} else if(url == '/rename'){
fileOp.rename('pinkfloyd.txt', 'tool.txt', function(err, done){
if(err){
response.end(err)
}
else{
response.end('done', done)
}
})
} else {
response.end('form default page');
}
console.log('client connected to server');
console.log('request url >>', request.url);
// request response cycle must be completed
// response.end('hi from node server'); response cannot sent more than once
});
server.listen(8080, function (err, done) {
if (err) {
console.log('server listening failed');
}
else {
console.log('server listening at port 8080');
console.log('press CTRL + C to exit from server');
}
});

Answer 1

In this section of code:
fileOp.rename('pinkfloyd.txt', 'tool.txt', function(err, done){
if(err){
response.end(err)
}
else{
response.end('done', done)
}
You are calling response.end('done', done). But, the fs.rename() callback does not have a done argument - it only has the err argument because there's no data to communicate back - the rename either succeeded or it didn't . So, done will be undefined. So you're calling:
response.end('done', undefined);
The function signature for response.end() is this:
response.end([data[, encoding]][, callback])
So, you're trying to send undefined for the encoding. That is not correct.
Your rename function should be change from this:
function rename(oldname, newname, cb){
fs.rename(`./bands/${oldname}`, `./bands/${newname}`, function(err,done){
if(err){
cb(err)
return
}
cb(null,done)
})
}
to this:
function rename(oldname, newname, cb){
fs.rename(`./bands/${oldname}`, `./bands/${newname}`, function(err){
if(err){
cb(err);
return
}
cb(null); // no 2nd argument here
})
}
or even simpler:
function rename(oldname, newname, cb){
fs.rename(`./bands/${oldname}`, `./bands/${newname}`, cb);
}
FYI, it appears you're using .end() improperly a bunch of places in your code where you do this:
response.end('done', someData);
That's not how it works. You aren't emitting an event. You're commanding the end of the http response and you need to follow this function signature:
response.end([data[, encoding]][, callback])
So, you'd probably just do response.end(data), if data was a string.