Mongoose assign a collection to another

Question

I am trying to add a post to a user collection after the user was created with empty posts. I have tried with populate with no success .. any help is much appreciated.

// Post Model
const mongoose = require('mongoose');
const { Schema } = mongoose;
 
const UserModel = require('./user-model');
 
let PostSchema = new Schema({
  author: {
    ref: 'users',
    type: Schema.Types.ObjectId
  },
  content: String,
  description: String,
  date: {
    default: new Date(),
    type: Date
  },
  title: String,
  updatedAt: {
    default:  new Date(),
    type: Date
  }
});

let PostModel = mongoose.model('posts', PostSchema);
module.exports = PostModel;
// User Model 
 
const mongoose = require('mongoose');
const { Schema } = mongoose;
 
const PostModel = require('./post-model');
 
let UserSchema = new Schema({
  name: {
    type: String
  },
  email: {
    lowercase: true,
    type: String,
    trim: true,
    unique: true
  },
  password: {
    type: String,
  },
  postList: [{
    ref: 'posts',
    type: Schema.Types.ObjectId
  }],
});

const UserModel = mongoose.model('users', UserSchema);
module.exports = UserModel;

// save post controller
exports.savePost = (request, response, next) => {
  let { author, description, title } = request.body;
  let post = new PostModel({ author, description, title }).save();
  UserModel.findById(author)
    .then((user) => {
      user.postList.push(post);
      // Still Fails
      // How can i assign the post to the user ?
  });
}

Is there any way of doing this other then push or populate ?

Answer 1

exports.savePost = (request, response, next) => {
  let { user, description, title } = request.body;

  let post = new PostModel({ user, description, title });

  post.save()
    .catch((error) => {
      if (error) 
        throw new Error(error);
    })
    .then((post) => {
      UserModel.findOneAndUpdate({ _id: user }, {$push: { postList: post._id } })
      .populate('postList')
      .catch((error) => {
        if (error) 
          throw new Error(error);
      })
      .then((user) => {
        user.postList.forEach((item, postion) => {
          console.log(`${item} -at ${postion} \n`);
        });
      });

  });

}

This is what i did and it worked after all. I don't know if this is the correct solution but this is working.

Answer 2

To solve this problem I prefer to use $push of mongo

UserModel.findOneAndUpdate({
    _id: author.id,
   {
        $push: {
                postList: post
            }
        }

});

Answer 3

You need to follow this process to save successfully

1. Save post if success then
2. Update user to push postId in postlist

can try this one

exports.savePost = (request, response, next) => {
  let post = new PostModel(request.body)

  post.save(function(err, data) {
    if(err) {
       //return error
    }
    // check by console your author is present or not
    // let author in your req.body
    let author = req.body.author
    UserModel.findOneAndUpdate({_id: author},{$push: {postList: post._id}},{new:true} function(error, user) {
        if(error) {
          // return error
        }
        console.log(user)
        // return success
    })
  });
}