Populate before adding: RangeError: Maximum call stack size exceeded

Question

I want to realise an online editor like plunker. I have defined the following data structure: a post (ie, a project) contains a list of folders (which means different versions of the post), and a folder is just a list of files.

var PostSchema = new mongoose.Schema({
  folders: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Folder' }]
  ...
});

var FolderSchema = new mongoose.Schema({
    files: [{ name: String, body: String, editorOption: Object }],
    post: { type: mongoose.Schema.Types.ObjectId, ref: 'Post' }
})

I want to use the following request to add a folder/version (by the save button on the editor). Note that, because a post can be opened in different places at the same time, we have to fetch the post from the database before adding a version to it, then we return the up-to-date post to the controller.

o.addFolder = function (id, folder) {
    return $http.post('/posts/' + id + '/editor/folders', folder, {
        headers: { Authorization: 'Bearer ' + auth.getToken() }
    })
}

router.post('/posts/:post/editor/folders', auth, function (req, res, next) {
    req.post.populate('folders', function (err, post) {
        if (err) return next(err);
        var folder = new Folder(req.body);
        folder.post = post;
        folder.save(function (err, folder) {
            if (err) return next(err);
            console.log("3 folder: "); console.log(folder);
            console.log("4 post: "); console.log(post);
            post.folders.push(folder);
            console.log("5 folder: "); console.log(folder);
            console.log("6 post: "); console.log(post);
            post.save(function (err, post) {
                if (err) return next(err);
                res.json({ folder: folder, post: post })
            })
        })
    })
});

Here is a test log which tries to add a folder of 2 files to an empty post:

3 folder: 
{ __v: 0,
  post: 
   { _id: 58b5e86d8e328f58f3e87ac2,
     __v: 0,
     folders: [] },
  _id: 58b5e86d8e328f58f3e87ac3,
  files: 
   [ { name: 'index.html',
       body: '<!DOCTYPE html>\n<body>\nindex.html\n</body>\n</html>',
       editorOption: [Object],
       _id: 58b5e86d8e328f58f3e87ac5 },
     { name: 'script.js',
       body: '',
       editorOption: [Object],
       _id: 58b5e86d8e328f58f3e87ac4 } ] }
4 post: 
{ _id: 58b5e86d8e328f58f3e87ac2,
  __v: 0,
  folders: [] }
5 folder: 
events.js:85
      throw er; // Unhandled 'error' event
            ^
RangeError: Maximum call stack size exceeded

Does anyone know what's wrong there?

It means that you're experiencing unbounded recursion, although after glancing at the code its not immediately obvious (at least to me) where... its also a bit hard to follow because of all the variable shadowing you're doing. — Jared Smith, Feb 28 '17 at 19:46
They are nested callbacks, I don't see how recursion is possible... — SoftTimur, Feb 28 '17 at 19:49
It almost has to be the last call `res.json(...` otherwise you'd see 'here' printed over and over in devtools until you got the error for overflowing the call stack... unless its happening somewhere in code you didn't post. — Jared Smith, Feb 28 '17 at 19:53
My tests show it can not display log after `post.folders.push(folder);` — SoftTimur, Feb 28 '17 at 21:20
Hey SoftTimur I found some posts that have similar issues. http://stackoverflow.com/questions/16810449/when-to-use-next-and-return-next-in-node-js 'Unhandled error event' for me points to how you are handling unresolved callbacks. http://stackoverflow.com/questions/5384526/javascript-node-js-next Does writing return next() instead of return next(err) help with the error handling? — Matt Fernandez, Mar 01 '17 at 04:33

score 1 · Accepted Answer · answered Mar 01 '17 at 11:04

The following code accomplishes what I want. Apparently, req.post.folders.push(folder) can push folder to the up-to-date post. And we do populate in the end.

router.post('/posts/:post/editor/folders', auth, function (req, res, next) {
    var folder = new Folder(req.body);
    folder.post = req.post;
    folder.save(function (err, folder) {
        if (err) return next(err);
        req.post.folders.push(folder);
        req.post.save(function (err, post) {
            if (err) return next(err);
            req.post.populate('folders', function (err, post) {
                if (err) return next(err);
                res.json(post);
            })
        })
    })
});

Populate before adding: RangeError: Maximum call stack size exceeded

1 Answers1