<-My Blog->

In this article, we gonna learn how to create, update and delete objects from an array of objects.

Let's take an example or article and comments.

Article Model

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

const commentSchema = new Schema(
    {
        comment: String
    }, 
    {
        timestamps: true
    }
);

const articleSchema = new Schema(
    {
        title: String, 
        description: String, 
        comments: [commentSchema]
    }, 
    {
        timestamps: true
    }
);

const Article = mongoose.model('Article', articleSchema);

module.exports = Article;

 Article Stored In MongoDB

{
    "title": "What is Lorem Ipsum ?",
    "description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry.",
    "_id": "632f4d18f33af31a4f257f74",
    "comments": [],
    "createdAt": "2022-09-24T18:31:52.926Z",
    "updatedAt": "2022-09-24T18:31:52.926Z",
    "__v": 0
}

 Definition

findOneAndUpdate(filter, update, options)

updateOne(filter, update, options)

Update Operators

$push - Adds an item to an array.

$pull - Removes all array elements that match a specified query.

$  - Acts as a placeholder to update the first element that matches the query condition.

$set - Sets the value of a field in a document.

Ref:- Array Update Operators

1. Add a Comment

const articleId = '632f4d18f33af31a4f257f74';
const commentObject = { comment: 'Test comment' }; 
await Article.findOneAndUpdate(
    { _id: articleId }, 
    { $push: { comments: commentObject } }, 
    { new: true }
); 

Result:-

{
    "_id": "632f4d18f33af31a4f257f74",
    "title": "What is Lorem Ipsum ?",
    "description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry.",
    "comments": [
        {
            "comment": "Test comment",
            "_id": "63302f59d30a55a4aae6417e",
            "updatedAt": "2022-09-25T10:37:13.290Z",
            "createdAt": "2022-09-25T10:37:13.290Z"
        }
    ],
    "createdAt": "2022-09-24T18:31:52.926Z",
    "updatedAt": "2022-09-25T10:37:13.290Z",
    "__v": 0
}

 

2. Update a Comment

const commentId = '63302f59d30a55a4aae6417e';
const comment = 'Updated test comment';

await Article.findOneAndUpdate(
    { 'comments._id': commentId }, 
    { $set: { 'comments.$.comment': comment } }, 
    { new: true }
);

Result:-

{
    "_id": "632f4d18f33af31a4f257f74",
    "title": "What is Lorem Ipsum ?",
    "description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry.",
    "comments": [
        {
            "comment": "Updated test comment",
            "_id": "63302f59d30a55a4aae6417e",
            "updatedAt": "2022-09-25T10:39:16.605Z",
            "createdAt": "2022-09-25T10:37:13.290Z"
        }
    ],
    "createdAt": "2022-09-24T18:31:52.926Z",
    "updatedAt": "2022-09-25T10:39:16.605Z",
    "__v": 0
}

 

3. Delete a Comment

const commentId = '63302f59d30a55a4aae6417e'; 

await Article.findOneAndUpdate(
    { 'comments._id': commentId }, 
    { $pull: { comments: {  _id: commentId } } }, 
    { new: true }
); 

Result:-

{
    "_id": "632f4d18f33af31a4f257f74",
    "title": "What is Lorem Ipsum ?",
    "description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry.",
    "comments": [],
    "createdAt": "2022-09-24T18:31:52.926Z",
    "updatedAt": "2022-09-25T10:43:13.245Z",
    "__v": 0
}