Unlike relational database NoSql (MongoDB) don’t have relation between documents. Even though we can set relation by placing sub document inside one document using the Object id, which is generated by the MongoDB.
The Modal objects
In the modal object of Post we can define a field for user which is another modal in our project.
The User Schema
const mongoose = require('mongoose');
const UserSchema = new mongoose.Schema({
name :{
type:String,
required: '{PATH} is required!'
},
,{
timestamps: true
})
module.exports = mongoose.model('User',UserSchema);The Post Schema
const mongoose = require('mongoose');
const PostSchema = new mongoose.Schema({
title: {
type: String,
required: '{PATH} is required!'
},
content: {
type: String,
required: '{PATH} is required!'
},
user: { type: mongoose.Schema.Types.ObjectId, ref: 'User' }
}, {
timestamps: true
})
module.exports = mongoose.model('Post', PostSchema);
In the user we had defined a field user, which is intended to store the user object ( MongoDB object ID), which can be used for populating the Object later.
In the express route method we have the following
const Post = require('../../models/post');
const User = require('../../models/user');
module.exports = {
create: async (req, res) => {
try {
console.log(req.params);
user = req.params;
id = user.id;
const {
title,
content,
} = req.body;
const post = await Post.create({
title,
content,
user: id
});
await post.save();
In the constructor , passed the user Object ID to the user field. The resulted MongoDB doc look like the following
New Post:{
_id: 5fee99c33cbe8b25d0ced080,
title: 'Happy New Year',
content: 'Happy New Year MEssage',
user: 5fe4ab1e69b8d525c44ec293,
createdAt: 2021-01-01T03:40:51.340Z,
updatedAt: 2021-01-01T03:40:51.340Z,
__v: 0
}
So How can we use the user objectID ?
Using the populate command we can get the complete User information as follows
Post.findById(post._id).populate('user').exec(function(error, post) {
console.log('New post - > ' + post);
})
and the resulted document will be
{
"_id": "5fe6ca34443a4d0f54aafece",
"title": "Flutter apps",
"content": "We are conducting a free workshop on Flutter",
"user": {
"_id": "5fe4db85a4896d069006601b",
"name": "emma",
"createdAt": "2020-12-24T18:18:45.224Z",
"updatedAt": "2020-12-24T18:20:47.857Z",
"__v": 1
},
That’s it. Following MongoDB posts deserve your attention
- How to clear all element in mongoose object array in Nodejs - How to clear elements in a mongodb object array
- How to export multiple components in Reactjs - How to render export multiple components in React
- How to add element to mongoose object array in Nodejs - How to add element to a mongodb object array
- How to interact with input in Reactjs - How to handle state and event of input element in React apps
- How to populate multiple MongoDB objects on the same path in express-node - How to populate multiple objects in MongoDB in the same path
- How to populate selected fields in a mongo document path in expressjs - How to populate object in mongo doc at a specific path with specific fields
- How to populate and display nested mongo objectin express-node route - How to populate object in express-MongoDB app
- How to render mongo object in Reactjs - How to render MongoDB object/ObjectId in React/MERN app
- How to render mongo document in Reactjs - How to render mongo document in react component
- How to filter MongoDB object list in express-node app - How to filter a mongo object list in document in express-node app
