getVehicles.js

    getVehicles(req, res, {UserModel, UserVehicleModel, VehicleModel}) {
        const username = req.body.username.toLowerCase();

        UserModel.find({ username: username}, (err, arr) => {
            if (err) throw err;
            if (arr.length !== 1) throw console.log(`incorrect number of users ${username}: ${arr.length}`);
            const user = arr[0];

            const vehicleArr = [];
            for (let VehicleId in user.ownedIds) {
                UserVehicleModel.findOne({_id: VehicleId}, (err, ownedVehicle) => {
                    if (err) throw err;
                    VehicleModel.findOne({_id: ownedVehicle.vehicleId}, (err, vehicle) => {
                        if (err) throw err;
                        
                        vehicleArr.push({
                            year: vehicle.year,
                            make: vehicle.make,
                            model: vehicle.model,
                        });
                    });
                });
            }

          
          res.json(vehicleArr);

        });
    }