mongodb mongoose full join on array-CodePudding

I have twoo collections I would like to preform a 'join' on.
The first one who has the reference is parrent.
The second one is calld child

This is how the object parrent looks like:

{
    "_id": "id_123"
    "name": "name",
    "children": ["id_child_1", "id_child_2", ...]
}

model/par.js looks like this:

const mongoose = require('mongoose');

const Par= mongoose.model('parrent',new mongoose.Schema({}), 'parrent');

exports.Par= Par;

route/par.js looks like this:

const {Par} = require('../models/par'); 
const express = require('express');
const router = express.Router();

router.get('/', async (req, res) => {
    const par = await Par.find();
    res.send(par);
  });

module.exports = router

The route child and model child looks exactly the same. (This is a simplefied version of the case).

I would like to return something like this:

{
    "_id": "id_123"
    "name": "name",
    "children": [{"name":"child1"}, {"name":"child2"}, ...]
}

I couldn't find a solution that worked, is not depricated, or one that uses this architecture.

CodePudding user response：

If I've understood correctly you can get it using simply a $lookup like this:

db.parent.aggregate([
  {
    "$lookup": {
      "from": "child",
      "localField": "children",
      "foreignField": "_id",
      "as": "children"
    }
  }
])

Example here

Or using $project to not output the _id in children array: example