Mongoose not adding virtual property in the response object using virtual populate - node.js

Question

So in my project i have two different models . Tour Model and Review Model. Review Model has parent reference of tour id. I want to add virtual populate on tour model so that I can get all reviews related to the tour. Basically doing it other way round.
So what I am expecting here is that whenever I hit a route on getTour I should see a property called "reviews" added to the response object but there is actually isn't. Please tell me is there anything I'm missing here.
const mongoose = require('mongoose');
const slugify = require('slugify');
const User = require('./userModel');
const Review = require('./reviewModel');
const tourSchema = new mongoose.Schema(
{
name: {
type: String,
required: [true, 'A tour must have a name'],
unique: true,
maxlength: [40, 'A tour namme must have less or equal 40 characters'],
minlength: [10, 'A tour namme must have greater or equal 10 characters'],
},
slug: String,
duration: {
type: Number,
required: [true, 'A tour must have a duration'],
},
maxGroupSize: {
type: Number,
required: [true, 'A tour must have a GroupSize'],
},
difficulty: {
type: String,
required: [true, 'A tour must have difficulty'],
},
ratingsQuantity: {
type: Number,
default: 0,
},
ratingsAverage: {
type: Number,
default: 4.5,
min: [1, 'Rating must be above 1.0'],
max: [5, 'Rating must be below 5.0'],
},
price: {
type: Number,
required: [true, 'A tour must have a price '],
},
priceDiscount: {
type: Number,
validate: {
validator: function (val) {
return val < this.price;
},
message: 'Discount must be lower than the price',
},
},
summary: {
type: String,
trim: true,
required: [true, 'A tour must have summary'],
},
description: {
type: String,
trim: true,
},
imageCover: {
type: String,
required: [true, 'A tour must have a cover image'],
},
images: [String],
createdAt: {
type: Date,
default: Date.now(),
},
startDates: [Date],
secretTour: {
type: Boolean,
dafault: false,
},
startLocation: {
//Geo json
type: {
type: String,
default: 'Point',
enum: ['Point'],
},
coordinates: [Number],
address: String,
description: String,
},
locations: [
{
type: {
type: String,
default: 'Point',
enum: ['Point'],
},
coordinates: [Number],
address: String,
description: String,
day: Number,
},
],
guides: [
{
type: mongoose.Schema.ObjectId,
ref: 'User',
},
],
},
{
toJSON: { virtuals: true },
toObject: { virtuals: true },
}
);
tourSchema.virtual('reviews', {
ref: 'Review', //name of model
foreignField: 'tour', //foreign property in review model
localField: '_id',
});
const Tour = mongoose.model('Tour', tourSchema);
module.exports = Tour;
const mongoose = require('mongoose');
const slugify = require('slugify');
const reviewSchema = new mongoose.Schema(
{
review: {
type: String,
required: true,
},
rating: {
type: Number,
min: 1,
max: 5,
required: true,
},
createdAt: {
type: Date,
default: Date.now,
},
user: {
type: mongoose.Schema.ObjectId,
ref: 'User',
required: [true, 'Review must belong to a user'],
},
tour: {
type: mongoose.Schema.ObjectId,
ref: 'Tour',
required: [true, 'Review must belong to a tour'],
},
},
{
toJSON: { virtuals: true },
toObject: { virtuals: true },
}
);
reviewSchema.pre(/^find/, function (next) {
this.populate({
path: 'user',
select: 'name',
}).populate({
path: 'tour',
select: 'name',
});
next();
});
const Review = mongoose.model('Review', reviewSchema);
module.exports = Review;

Answer 1

You just have to populate reviews field. so after doing virtual property write this code below it in file contains tourSchema.
If you want to find single tour
tourSchema.pre('findOne', function (next) {
this.populate('reviews');
next();
});