CODEWITHSUNDEEP
javascriptnode.jsmongodbasynchronousmongoose
Trong Lam Phan
Trong Lam Phan

Reputation: 2412

Use value in mongoose scope function

I'd like to find mails of a user by his id. But i have a problem because mongoose function is async.

Mail.find({receiver_id: '#id#'}, function(err, mails) {
    var result = [];
    var count = 0;
    if (mails.length > 0) {
        for (m of mails) {
            User.findById(m.sender_id, function(err, user) {
                if (user) {
                    result.push({
                        id: m._id,
                        title: m.title,
                        body: m.body
                    });
                    if (++count == mails.length) {
                        res.json({success: true, data: result});
                    }
                }
            });
        }
    } else {
        res.json({success: false, error: 'Cannot find any email'});
    }
});

The problem is, when i got my result, all mails were the same. As i understood, because User.findById is an async function, so when i use m in that function, the m always represents the last child of mails.

I've figured out that if i pass some variables as the second param of findById function, it should work:

User.findById(m.sender_id, {id: m._id, title: m.title, body: m.body}, function(err, user) {
    if (user) {
        result.push({id, title, body});
        if (++count == mails.length) {
            res.json({success: true, data: result});
        }
    }
});

but because my document doesn't have only three fields, so i think there's another better solution.

How can i get it right ? Thanks !

Upvotes: 0

Views: 195

Answers (1)

Mykola Borysyuk
Mykola Borysyuk

Reputation: 3411

var async = require("async");
var yourResult = [];
async.each(mails, function(mailObj, done){
   User.findById(mailObj.sender_id, function(err, user) {
       //add data into result. call async callback function.
       done();
   })
}, function(err){
  //final callback write res here
  result.push(yourResult);
  res.json({success: true, data: result});
});

Async docs here. http://caolan.github.io/async/index.html Hope this helps.

Upvotes: 2

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