Mongoose: Get the data from 2 collections, like get products that have same category type like fruits - mongodb

Question

I am very new to mongoDB and mongoose and I also know questions like this has been already asked but still I didn't get any luck.
So what I am trying to do is I have 2 collections one is products and second is categories and I am trying to get the products that are of category type: fruits
product.model.js
const mongoose = require('mongoose')
const productSchema = new mongoose.Schema({
category: {
type: mongoose.Schema.Types.ObjectId,
ref: 'Category'
},
name: {
type: String,
required: true,
unique: true
},
price: {
type: Number,
required: true
},
image: {
type: String,
required: true
},
description: {
type: String,
required: true
}
})
const Product = mongoose.model('Product', productSchema)
module.exports = Product
category.model.js
const mongoose = require('mongoose')
const categorySchema = new mongoose.Schema({
name: {
type: String,
required: true,
unique: true,
lowercase: true
}
})
const Category = mongoose.model('Category', categorySchema)
module.exports = Category
products collecction
[ { _id: 5ffc9795355f3707ec326f51,
name: 'apple',
price: 80,
image: 'apple1.jpg',
description:
'Do you really need description for this ??',
category: 5ffc94e8a7542a37101a119c,
__v: 0 },
{ _id: 5ffd54409793c33b183376b8,
name: 'Beef',
price: 180,
image: 'beef1.jpg',
description: 'Don\'t you dare to ask about beef in india',
category: 5ffc94dda7542a37101a119b,
__v: 0 },
{ _id: 5ffd54969793c33b183376b9,
name: 'Mango',
price: 100,
image: 'mango1.jpg',
description:
'Have some manog because you cannot eat the bottle of slice like katrina kaif do, its crazy',
category: 5ffc94e8a7542a37101a119c,
__v: 0 } ]
categories collection
[ { _id: 5ffc947ea7542a37101a119a, name: 'vegitables', __v: 0 },
{ _id: 5ffc94dda7542a37101a119b, name: 'non-veg', __v: 0 },
{ _id: 5ffc94e8a7542a37101a119c, name: 'fruits', __v: 0 } ]
Now I want to the get the products whose category are fruits
I know I have to use aggregation and lookup for this I also tried but didn't get any luck, this is my code
const Product = require('./models/product')
const Category = require('./models/category')
const test = async () => {
try {
var query = [
{
$lookup: {
from: "product",
localField: "category",
foreignField: "_id",
as: "product"
}
}]
const productCate = await Product.aggregate(query)
console.log(productCate)
// const productCat = await Product.find().populate({
// path: 'category',
// match: {name: 'fruits'}
// }).exec()
// console.log(productCat)
}catch(e) {
}
}
test()
UPDATE-1
I also tried ppuplate but still didn't get the response as expected, this is my code:
const test = async () => {
try {
const productCat = await Product.find().populate({
path: 'category',
match: {name: 'fruits'}
}).exec()
console.log(productCat)
}catch(e) {
}
}
test()
this is my output
[ { _id: 5ffc9795355f3707ec326f51,
name: 'apple',
price: 80,
image: 'apple1.jpg',
description:
'Do you really need description for this, how dumb are you ??',
category: { _id: 5ffc94e8a7542a37101a119c, name: 'fruits', __v: 0 },
__v: 0 },
{ _id: 5ffd54409793c33b183376b8,
name: 'Beef',
price: 180,
image: 'beef1.jpg',
description: 'Don\'t you dare to ask about beef in india',
category: null,
__v: 0 },
{ _id: 5ffd54969793c33b183376b9,
name: 'Mango',
price: 100,
image: 'mango1.jpg',
description:
'Have some manog because you cannot eat the bottle of slice like katrina kaif do, its crazy',
category: { _id: 5ffc94e8a7542a37101a119c, name: 'fruits', __v: 0 },
__v: 0 } ]
Here I also get the beef that is fall under non-veg category but with the category null. Actually I only want the fruits category products.

Answer 1

you can following this code
const test = async () => {
try {
let categoryId = await Category.findOne({name:"fruits"}).select("_id")
const productCat = await Product.find({category:categoryId}).populate(
"category"
).lean()
console.log(productCat)
}catch(e) {
}
}
test()

Answer 2

you can do with with populate match without using aggregation:
Product.find().populate({
path: 'category',
match: { 'name': 'fruits' }
})
.exec()