Cannot read property 'push' of undefined when creating data in mongoose - node.js

Question

I am creating a express.js app and I made a database in mongoose for testing purpose. the database is inside a function seedDB() that I export to my app.js file. Creating the seed database has no error but when I add a new "review" inside of that data. it is saying cannot read property "push" of undefined even though my mongoose model is set correctly.
I have two collections inside mongoDB called "tours" and "reviews"
I tried looking up the tours inside mongo shell with db.tours.find() and I find my "review" which is an array that is associated with the review collection is set up correctly. But when I looked up db.reviews.find() . It is also there but it has about x4 result that my expected result.
I tried checking if I just forgot a parenthesis, curly brace but I think that's not the problem.
I also tried looking at my models over and over and changing again but there is also no problem
const tours = require("./models/tours");
const Review = require('./models/reviews');
let tourData = [{
image: "image.jpg",
place: "Place",
name: "name",
description: "this is a description",
price: 1234,
info: "this is a great tour"},
{
image: "image.jpg",
place: "Place",
name: "name",
description: "this is a description",
price: 1234,
info: "this is a great tour"},
{
image: "image.jpg",
place: "Place",
name: "name",
description: "this is a description",
price: 1234,
info: "this is a great tour"},
]
function seedDB(){
tours.deleteMany({}, (err)=>{
if(err){
console.log(err);
}
console.log("removed tours!");
//add a few tours
tourData.forEach(function(seeds){
tours.create(seeds, (err, data)=> {
if(err){
console.log(err)
} else {
console.log('added all tours!');
//create a comment
Review.create(
{
text: "this place is great! ",
author: "Arnold"
}, (err, comment)=> {
if(err){
console.log(err)
} else {
tours.reviews.push(comment); //why is this undefined? I set it up correctly
tours.save();
console.log("created new review")
}
});
}
});
});
});
};
module.exports = seedDB
up until console.log('added all tours!'); it is going well but when I put the Review.create(), it now has error specifically the tours.reviews.push(comment);
//tours.js model
const mongoose = require('mongoose');
var ToursSchema = new mongoose.Schema({
image: String,
place: String,
name: String,
description: String,
price: Number,
info: String,
creator: {
id: {
type: mongoose.Schema.Types.ObjectId,
ref: "User"
},
username: String
},
reviews:[
{
type: mongoose.Schema.Types.ObjectId,
ref: "Review"
}
]
});
let Tours = mongoose.model('Tour', ToursSchema);
module.exports = Tours;
reviews.js model
const mongoose = require('mongoose');
var reviewSchema = mongoose.Schema({ //I also tried doing new Mongoose.Schema({
text: String,
author: String
});
module.exports = mongoose.model('Review', reviewSchema);
expected results in console should be
removed tours!
added all tours!
added all tours!
added all tours!
created new review
created new review
created new review
and the actual results in the mongo database is have an array of reviews inside the tours collections.

Answer 1

Multiple things:
tours is your model, not your instance. You want to push into the reviews of one or all of your instances, which in your case is data. So in your case you can do something like data[0].reviews.push(comment). I can see how you this gut mixed up, since tours is lowercase, which makes it look like a instance, not a model.
The second worst variable name after data is data2 :-P
Consider replacing your callback with the far easier to read and maintain async/await syntax
don't directly require your models, but rather register your models and use mongoose.model('tours')