node.js ncp | fs.readdir | missing files | use of callback

Question

I´ve tried to copy a lot of files in folder by "ncp", but every time I check if the files are copied, not all of them are there. There are always some files are missing.

I´ve tried to use fs.readdir to check that are all files there but fs gives me the same result there are some files are missing

my ncp code

ncp(path.join(req.body.uploadPath,req.body.packageName,resourceDirectoryName), path.join(req.body.uploadPath,req.body.packageName),  (err) => {
    if (err) {
     //devmode report
     devMode.report('**error** '+err); 
    }
})

my fs code

fs.readdir(path.join(req.body.uploadPath,req.body.packageName,resourceDirectoryName), (err, files)=>{
              console.log('####', files)
})

And this is the fs.readdir result

This is the folder with all files that I want to copy

This is the list of files it didn't copy

Answer 1

• CLUE 1:

  Check the order reported on your fs.readdir

• CLUE 2:

  Now, as it´s alphabetical order, look for the next ocurrence in your list (alphabetically)

• CLUE 3:

  Check for special characters on it´s name.

• CLUE 4 - TEST A POSSIBLE SOLUTION*

  As you can see, there is a space on the name of `new dictionary.json". Remove the spaces on this name and try again.

• CLUE 5 - Change your call, and add StopOnError

Add an StopOnError option to show if it stops there and why

ncp ( 
  path.join(req.body.uploadPath, req.body.packageName,   resourceDirectoryName),
  path.join(req.body.uploadPath,req.body.packageName), 
  {stopOnErr: true},
  (err) => {
        if (err) 
        {
          return console.error(err);
        }
      console.log("ok");
   }
)

SOLUTION

After dealing with this for a little of time, the problem was located: The user was executing the fs.readdir right after the execution of NCP. As NCP is asyncronous, fs.readdir was not reading the whole bunch of copied files, as they were still not copied.

Then, just a delay before fs.readdir was the solution to see all of them. Not a Spaces or special characters thing.

FINALLY, A REAL SOLUTION

As async programming has a first-day-of-school where everybody learns how to deal with callbacks, there is an example to deal with callbacks, and solve the question.

var ncp = require('ncp').ncp;
var fs = require('fs');


ncp.limit = 16;
var source="dir1"
var destination="dir2"
console.log('Starting');
console.log(new Date().toISOString());

ncp(source, destination, mycallback );

function mycallback(err)
{
 //here we are inside a callback declared in an outer function
 if (err) {
   return console.log(err);
 }
 console.log('done!');
 console.log(new Date().toISOString());
 fs.readdir(destination, function (err, files){
            console.log("Files Copied to Dir2 "+ files.length);
            //here we are inside fs.readdir callback
            copyTwo();
              });
 //as fs.readdir is also async, I cannot execute copyTwo() here, and I must execute inside fs.reddir callback
}


function copyTwo()
{
console.log('Starting CopyTwo');
console.log(new Date().toISOString());
source="dir2"
destination="dir3"
  //This function uses an embedded callback
  ncp(source, destination, function (err)
  {
   // here we are inside the function declared (with-no-name) to use directly asembedded  callback
   if (err) {
     return console.log(err);
   }
   console.log('done!');
   console.log(new Date().toISOString());
   fs.readdir(destination, function (err, files){
              console.log("Files Copied to Dir3 "+ files.length);
                });
  });
}




[admin-sp@localhost pruebaApp]$ ls dir1 | wc -l
7777
[admin-sp@localhost pruebaApp]$ ls dir2 | wc -l
0
[admin-sp@localhost pruebaApp]$ ls dir3 | wc -l
0
[admin-sp@localhost pruebaApp]$ node index.js
Starting
2018-05-01T00:55:50.683Z
done!
2018-05-01T00:55:57.063Z
Files Copied to Dir2 7777
Starting CopyTwo
2018-05-01T00:55:57.069Z
done!
2018-05-01T00:56:03.030Z
Files Copied to Dir3 7777
[admin-sp@localhost pruebaApp]$