CODEWITHSUNDEEP
node.jsmongodbexpressmongoose
dmr07
dmr07

Reputation: 1478

Mongoose: Populate after find()

I'm new to mongo and node js, here's what I'm trying to do:

The API is to check if there is an existing entry in the DB, based on the query.

Problem: In scenario (a), after creating document, the API sends "null" to the client.

Suspect: .populate() & .exec() runs before the API finishes creating a new document. The snippet from the code returns null: 

console.log('Inside IF' + video_res); // returns null

What's the best way to resolve this?

model_video.findOne( video_entry, 
        function(err, video_req) { // Send Back Object ID
            if (err) res.send(err);

        if (!video_req) { // Does not work
            console.log('-----STATUS : No Video Found');

            model_video.create(video_entry, function(err, video_res) {
                    console.log('Call back activated');
                    if (err) res.send(err);

                    console.log('Response is ' + video_res);
                    return video_res; // Does not work here!
            }); // Ends - Create
            console.log('Inside IF ' + video_res);
        } 

        else { // Works
            console.log('-----STATUS : Video Found')
            if (err) return res.send(err);
            var video_res = video_req;
            console.log('Response is ' + video_res);
            return video_res;
        };
    })
    .populate('_chirps')
    .exec(function(err, video_res) {
        if (err) return res.send(err);
        res.json(video_res);
        console.log('Final Output is ' + video_res)
    });

};

Your help is greatly appreciated!

Upvotes: 3

Views: 4920

Answers (1)

Yuri Zarubin
Yuri Zarubin

Reputation: 11677

The callback exec() callback executes immediately after your .findOne query, you need to put the rest of your code in that callback. I've refactored your code to make it more inline with what you're trying to do.

model_video.findOne(video_entry)
.populate('_chirps')
.exec(function(err, video_res) {
  if (err) return res.send(err);

  if (video_res) {
    console.log('-----STATUS : Video Found')
    console.log('Response is ' + video_res);
    res.json(video_res)
  }
  else {
    console.log('-----STATUS : No Video Found');

    model_video.create(video_entry, function(err, new_video_res) {
      if (err) return res.send(err);

      console.log('Response is ' + new_video_res);
      res.json(new_video_res);
    });
  }
})

Upvotes: 3

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