convert tree-manager npm module (filetree) for koajs / co compatibility - node.js

Question

How do I get a list of files compatible with co/yield (for koajs) ?
I am trying to convert this module for koa/co: https://www.npmjs.com/package/tree-manager
The original function is
fileModule.prototype.walkDir = function(dir, done) {
var self = this;
var results = [];
fs.readdir(dir, function(err, list) {
if (err) {
return done(err);
}
console.log(pending)
var pending = list.length;
if(!pending) {
return done(null, results);
}
list.forEach(function(file) {
var dfile = path.join(dir, file);
var el = {};
var fid = path.join(dir.replace(self.root, ''), file);
el.text = file;
el.id = fid;
fs.stat(dfile, function(err, stat) {
if(err) {
throw err;
}
if(stat.isDirectory()) {
return self.walkDir(dfile, function(err, res) {
el.children = res;
results.push(el);
!--pending && done(null, results);
});
}
el.icon = 'file'; // #TODO - to settings
el.a_attr = {id: fid};
results.push(el);
!--pending && done(null, results);
});
});
});
}
I can replace require('fs') with co-fs-plus (or extra)
so i can remove all fs callbacks with simple yield fs.xxx
but i don t understand the foreach loop :/
UPDATE (solution):
so ...
add wrap to co and adding dfile to the isDirectory function seems working
fileModule.prototype.walkDir = co.wrap(function*(dir) {
var self = this;
var list = yield fs.readdirAsync(dir);
// yield a list of promises
// created by mapping with an asynchronous function
var results = yield list.map(co.wrap(function*(file) {
var dfile = path.join(dir, file);
var fid = path.join(dir.replace(self.root, ''), file);
var el = {
text: file,
id: fid
};
try {
if (yield fs.isDirectoryAsync(dfile)) {
el.children = yield self.walkDir(dfile);
} else {
el.icon = 'file'; // #TODO - to settings
el.a_attr = {id: fid};
}
return el;
} catch(err) {
el.icon = 'file'; // #TODO - to settings
el.a_attr = {id: fid+' !! FILE UNREADABLE !!'};
return el;
}
}));
return results;
})
Thanks !

Answer 1

That loops runs all the actions in parallel, that's why it's so complicated (with the pending thingy and all). However, doing things in parallel is not really a strength of co, you should look into promises for that.
import fs from 'fs-extra-promise';
fileModule.prototype.walkDir = co(function*(dir) {
var self = this;
var list = yield fs.readdirAsync(dir);
// yield a list of promises
// created by mapping with an asynchronous function
var results = yield list.map(co(function*(file) {
var dfile = path.join(dir, file);
var fid = path.join(dir.replace(self.root, ''), file);
var el = {
text: file,
id: fid
};
if (yield fs.isDirectoryAsync()) {
el.children = yield self.walkDir(dfile);
} else {
el.icon = 'file'; // #TODO - to settings
el.a_attr = {id: fid};
}
return el;
}));
return results;
});