Pushing Object ID to Nested Array MongoDB/Mongoose

Question

so I'm trying to do a simple Thumbs Up system for an App I'm working on, but I'm having issues pushing the User ID to the likes Array. Heres what my code looks like:

Room Schema

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const classroomSchema = Schema({
    clName: String,
    clPosts: [{
        title: String,
        mssg: String,
        date: String,
        imageurl: String,
HERE==> likes: [{type: Schema.Types.ObjectId, ref: 'User'}] 
    }]
})

const Classroom = mongoose.model('Classroom', classroomSchema)
module.exports = Classroom

router

router.put('/put/classroom/post/like/:id', (req, res, next) => {
    var data = data = req.body
    Classroom.findByIdAndUpdate(
        {
            _id: req.params.id,
            "clPosts": { _id: data.post }
        },
        { $push: { "clPosts.$[outer].likes": [data.user] } },
        { "arrayFilters": [{ "outer._id": data.post }] }
    ).then((room) => {
         console.log("Done"); 
         res.json(room);
    }).catch(next)
})

I've tried following other suggestions here on SO but I'm not sure if I have something configured incorrectly or there is a better way of pushing an object into a nested array.

The Basic setup is, there is a Classroom Collection holding Classroom Objects. within The Classroom, there is posts Object Array, and inside that, a likes Array. The idea is whenever someone Likes the post, it saves the ObjectID of that user into the array, which I then use to count how many likes, etc...

If any more detail is needed please let me know, MongoDB doesn't have good documentation on nesting arrays.

user2814599 · Accepted Answer · 2018-10-24 15:01:13Z

1

clPosts is a subdocument. You query posts by _id -> "clPosts": { _id: data.post } but I believe, the query should look like this: "clPosts._id": { _id: data.post_id }

Since you use mongoose, you can do this:

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const ClassRoomPostsSchema = new Schema({
    title: String,
    mssg: String,
    date: String,
    mageurl: String,
    likes: [] // you will push ids here or else, if you need to store more data, e.g. date/time when like was given, create a schema for Likes e.g. likes: [likeSchema.schema]
})

const ClassRoomSchema = new Schema({
    clName: String,
    clPosts: [ClassRoomPostsSchema.schema]
})

Then in your code:

router.put('/put/classroom/post/like/:id', (req, res, next) => {
  ClassRoom.findOne({_id: req.params.id}, function(err, room) {
    if (err) return next(err);

    if (!room) return res.status(404).send('Classroom not found');

    //Find a post by id
    let post = ClassRoom.clPosts.id(data.post); // -> data.post_id

    if (!post) return res.status(404).send('Post not found');

    // Here you can push ids, but what is the idea behind? Maybe it makes more sense to count likes or push Like schemas (subdocument) to the array, e.g. post.likes.push(new Like(data));        
    post.likes.push();

    room.save(function(err) {
      if (err) return serverValidationError(req, res, err);
      res.status(200).send('success');
    });
  });      
})

edited Oct 24, 2018 at 15:01

answered Oct 24, 2018 at 8:54

user2814599

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1 Comment

Dilean Barroso Over a year ago

Hi thanks for the response, i realize i was putting the _id in the wrong place, but ive decided to go with your sugestion for creating a new schema for the likes, i hadnt thought about adding extra data to the like. i no longer need to push an object into a nested Array

Deval · Accepted Answer · 2018-10-24 08:05:54Z

1

Try this way

Classroom.findByIdAndUpdate(
        {
            _id: req.params.id,
            "clPosts._id": data.post
        },
        { $push: { "clPosts.$.likes": [data.user] } }
    ).then((room) => {
         console.log("Done"); 
         res.json(room);
    }).catch(next)

answered Oct 24, 2018 at 8:05

Deval

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1 Comment

Dilean Barroso Over a year ago

Hi thanks for the response, i realize i was putting the _id in the wrong place, but after trying your solution i continue to get the error: [ERROR] The positional operator did not find the match needed from the query.

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