Develop Reference

Pull element from array in mongodb

I'm using this schema for the USERS Collection
const usersSchema = new Schema({
username: {
type: String,
required: true,
},
email: {
type: String,
required: true,
unique: true,
},
password: {
type: String,
required: true,
select: false,
},
phone: {
type: Number,
required: true,
},
books: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "books",
},
],
});
and when the user want to delete a book in books collection, it should be delete in the user's books document (The above array) as well.
and I use this query but i get an error
const deleteBook = async (req, res, next) => {
try {
const { id } = req.query;
const deletedProduct = await books.findByIdAndDelete(id).populate(
"author"
);
// IT WORKS AND DELETE THE BOOK IN BOOKS COLLECTION
if (!deletedProduct) {
return next(new ErrorHandler("Product Was Not Found", 404));
}
await Users.findByIdAndUpdate(
deletedProduct.author._id,
{
$pull: { books: deletedProduct._id },
},
(err, docs) => {
// ERROR IS NULL IN HERE
console.log(err);
console.log(docs);
}
);
res.status(200).json("Success");
} catch (err) {
next(new ErrorHandler(err.message, 500));
}
};
Its My query but i get this error.
"Query was already executed: users.findOneAndUpdate({ _id: new ObjectId("THE USER'S ID"
i want to say. The book will be deleted from the books collection, but stay as same in the User's books array.

I get this error: this.$__.validationError = new ValidationError(this)

I am new to learning web dev using node.js and express.js. When I test my code in Postman the server crashes and gives me this error this.$__.validationError = new ValidationError(this).
I am creating backend server connected to MongoDB and the mongoose package.
Routes
const express = require('express')
const router = express.Router()
const {
create
} = require('./../controllers/courseControllers')
const {verifyAdmin, verify} = require('./../auth')
router.post('/create', verifyAdmin, async (req, res) => {
// console.log(req.body)
try{
create(req.body).then(result => res.send(result))
}catch(err){
res.status(500).json(err)
}
})
Controllers
const Course = require('../models/Course');
//CREATE A COURSE
module.exports.create = async (reqBody) => {
const {courseName, description, price} = reqBody
let newCourse = new Course({
courseName: courseName,
description: description,
price: price
})
// console.log(newCourse)
return await newCourse.save().then((result, err) => result ? result : err)
}
Schema
const mongoose = require('mongoose');
const courseSchema = new mongoose.Schema({
courseName: {
type: String,
required: [true, `Course name is required`],
unique: true
},
description: {
type: String,
required: [true, `Course description is required`]
},
price: {
type: Number,
required: [true, `Price is required`]
},
isOffered: {
type: Boolean,
default: true
},
enrollees: [
{
userId: {
type: String,
required: [true, `userId is required`]
},
enrolledOn: {
type: Date,
default: new Date()
}
}
]
}, {timestamps: true})
module.exports = mongoose.model("Course", courseSchema);

Given the information you provided, i can say that you are missing the enrollees parameter on creation whitin the controller, as enrollees has been set to required, i hope its usefull for you, if not let me know.

Mongoose populate replacing ObjectIds with empty array

I've been trying to use the mongoose populate function to connect two models. I can save an object but when trying to retrieve using populate the ObjectIds are just replaced with an empty array.
Many questions seem to have been asked but none have a solution that worked for me
user.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var Route = require('./route')
var passportLocalMongoose = require('passport-local-mongoose');
const postSchema = new Schema ({
text: {
type: String,
default: '',
required: true
}
}, {
timestamps: true
});
const UserSchema = new Schema({
firstname: {
type: String
},
posts: [postSchema],
route: [{
type: mongoose.Schema.Types.ObjectId,
ref: 'Route'
}]
}, {
timestamps: true
});
UserSchema.plugin(passportLocalMongoose);
const User = mongoose.model('User', UserSchema);
module.exports = User;
route.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
const locationSchema = new Schema ({
id: {
type: Number,
default: 0,
required: true
},
address: {
type: String,
default: '',
required: true
},
lat: {
type: Number,
default: 0,
required: true
},
lng: {
type: Number,
default: 0,
required: true
}
},{
timestamps: true })
const routeSchema = new Schema ({
locations: [locationSchema],
description: {
journey1: {
type: String,
default: '',
required: false
},
journey2: {
type: String,
default: '',
required: false
},
journey3: {
type: String,
default: '',
required: false
},
journey4: {
type: String,
default: '',
required: false
}
}
}, {
timestamps: true
});
module.exports = mongoose.model('Route', routeSchema);
within REST POST end point
User.findOne({_id: req.user._id}, function(err,user) {
if(user) {
var routed = new Route();
routed.locations = req.body.locations;
routed.description = req.body.description;
user.route.push(routed);
user.save()
.then((user) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'application/json')
res.json(user)
}, (err) => next(err))
} else {
console.log("errored")
err = new Error('User ' + req.body.username + ' not found');
err.status = 404;
return next(err);
}
})
within REST GET end point
User.findOne({_id: req.user._id})
.populate('route')
.then((user) => {
if(user){
console.log("user")
console.log(user)
console.log("routes")
console.log(user.route)
res.statusCode = 200;
res.setHeader('Content-Type', 'application/json')
res.json({success: true, routes: user.route});
}
}, (err) => next(err))
.catch((err) => next(err));
If I remove populate I'll get something like
[
new ObjectId("61f053af7ba46267f4893f8f")
new ObjectId("61f053af7ba46267f4893f8f")
new ObjectId("61f053af7ba46267f4893f8f")
]
from the GET end point but adding it back in returns
[].
My understanding is that in 'new Route()' I'm creating a new Route Object with an Id that gets stored in the User model/document(?). Then when I call populate mongoose searches the Route document for those Ids and converts them to the objects I want. The only issue I could think of is that I'm not creating the Route objects correctly and so no object is being stored with that Id which is why an empty array is returned when I come to try swap Ids with Route objects.
Any ideas or are we all just stumbling in the dark ?

Not entirely sure this is the correct method but instead of instantiating a Route object as displayed I used the Route.create(...) method and then pushed that to the route array and now populate works as expected

Api call finds already deleted documents

I've two endpoints: one that delete product document and one that retrieve the document.
After I delete the document throught by Id, the GET api call return me already the document even if it's deleted and It's not present on MongoDb.
Response of DELETE call returns { deletedCount: 1 }
Here code of GET product:
exports.getSingleProduct = (req, res, next) => {
let id = req.params.id;
Products.findById(id).populate({ path: 'internalColor' }).then(result => {
if(result && result.visible == true) {
res.status(200).json(result)
} else {
res.status(404).json({
message: 'product_not_found',
id: id
})
}
}).catch(err => {
res.status(404).json({
message: 'error_operation: ' + err,
id: id
})
});
}
Here code of DELETE product:
exports.deleteDefinallySingleProduct = (req, res, next) => {
let id = req.params.id;
console.log(id)
Products.deleteOne({ id: id }).then(result => {
if(result) {
res.status(200).json({
message: 'deleted_product'
});
}
}).catch(err => {
res.status(404).json({
message: 'error_operation: ' + err
})
})
}
Products Model
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const options = {
timestamps: true
}
const productSchema = new Schema({
name: {
type: String,
required: true
},
description: {
type: String,
required: true
},
price: {
type: Number,
required: true
},
externalUrl: {
type: String,
required: true
},
imgUrl: {
type: String,
required: true
},
brand: {
type: String,
required: true
},
visible: {
type: Boolean,
required: true
}
}, options);
const Product = mongoose.model('Products', productSchema);
module.exports = Product;

I think the error that you are facing is caused by a typo in your code.
exports.deleteDefinallySingleProduct = (req, res, next) => {
...
Products.deleteOne({ id: id }).then(result => {
if(result) {
// this code will run always
console.log(result) // will show { n: 0, ok: 1, deletedCount: 0 },
// That is, this section of code will run always despite of delete count being 0 or more due to the request to be excecuted successfully.
...
}
The correct implementation is here:
exports.deleteDefinallySingleProduct = (req, res, next) => {
...
Products.deleteOne({ _id: id }).then(result => {
...
}
This is because by default mongooose use _id representing the document id, unless create a custom id in the schema which you didn't do.

Can't push items into mongodb arrays

I'm trying to make a simple social media app using react, express and mongodb.
This is the user model:
const UserSchema = new mongoose.Schema(
{
username: { type: String, required: true, unique: true },
password: { type: String, required: true },
email: { type: String, required: true, unique: true},
followers: { type: Array, required: false },
following: { type: Array, required: false },
likes: { type: Array, required: false},
},
{ collection: 'users' }
)
This is the express server:
app.post('/api/follow', async (req, res) => {
const {token, username} = req.body
if (token === null)
{
return res.json({status: 'error'})
}
const user = await User.findOne({username}).lean()
const _visitor = jwt.verify(token, JWT_SECRET)
const visitor = await User.findOne({username: _visitor.username})
if (!user)
{
return res.json({status: 'error', error: 'User not found.'})
}
if (!visitor)
{
return res.json({status: 'error', error: 'User not found.'})
}
visitor.following.push(user._id)
user.followers.push(me._id)
return res.json({status: 'ok'})
})
But when I check the mongodb compass the following and followers arrays are empty.

The best way is to use findOneAndUpdate() method to update a value.
Also, if you are updating from two different collections you can use transactions. This is optional but can be useful to avoid inconsitences in your DB.
So your code can be something similar to this:
const updateVisitor = await User.findOneAndUpdate(
{
username: _visitor.username
},
{
$push:{
following: user._id
}
})
Example here
An the same code for user:
const updateUser = await User.findOneAndUpdate(
{
username: username
},
{
$push:{
followers: me._id
}
})