How to populate data from another collections in mongoose? - node.js

Question

I want to populate the busNumber from bus Bus table to the trip table.
Here's the bus model
const busSchema = new mongoose.Schema(
{
busNumber: {
type: String,
unique: true,
required: true,
},
seats: {
type: Number,
},
},
{
timestamps: true,
}
);
now I want to show the bus number inside the trip table instead of bus._id. I know how to exclude data but don't know how to include data from other collections.
here's the route model where I included the bus model
const routeSchema = new mongoose.Schema({
location:{
type: mongoose.Schema.Types.ObjectId,
ref: 'Location',
required: true
},
duration: {
type: Number,
required: true,
},
Bus:{
type: mongoose.Schema.Types.ObjectId,
ref:"Bus",
required: true
},
date: {
type:String,
required: true
},
},
{
timestamps: true,
});
here's the query:
router.get("/trips", async (req, res) => {
if ((!req.query.departure && !req.query.arrival) || !req.query.date) {
return res.send({
error: "Please enter the data to get the trip",
});
}
const { departure, arrival, date } = req.query;
const locations = await Location.find({
"departureLocation.name": departure,
"arrivalLocation.name": arrival,
});
const ids = locations.map(location => location._id);
const routes = await Route.find({
$and: [{ location: { $in: ids } }, { date }],
}).select(['-busId', '-location', '-_id', '-createdAt', '-updatedAt', '-__v']);
return !routes ? res.status(404).send() : res.status(200).send(routes);
});
Here's the result I am getting https://i.stack.imgur.com/AwK5N.png
How to use the populate() function to get data from another collection in mongoose

Answer 1

use this code for your populate Bus key
router.get("/trips", async (req, res) => {
if ((!req.query.departure && !req.query.arrival) || !req.query.date) {
return res.send({
error: "Please enter the data to get the trip",
});
}
const { departure, arrival, date } = req.query;
const locations = await Location.find({
"departureLocation.name": departure,
"arrivalLocation.name": arrival,
});
const ids = locations.map(location => location._id);
const routes = await Route.find({
$and: [{ location: { $in: ids } }, { date }],
}).populate("Bus").select(['-busId', '-location', '-_id', '-createdAt', '-updatedAt', '-__v']);
return !routes ? res.status(404).send() : res.status(200).send(routes);
});