问如何根据定价层为我的SaaS应用程序创建功能限制？

EN

module.exports.showActivations = async (req, res) => {
    const user = await User.findById(req.params.id);
    const qr = await Qr.find({ user: user._id }).populate('event');

    const qrAgg = await Qr.aggregate([
        {
            $match: { user: user._id }
        },
        {
            $lookup: {
                from: 'events',
                localField: 'event',
                foreignField: '_id',
                as: 'event'
            }
        },
        {
            $unwind: '$event'
        },
        {
            $sort: { 'event.event_start': -1 }
        }
    ]);
    const activeEvents = await Event.find({ user: user.id, event_end: { $gte: Date.now() } }).populate('qr');
    
    // for loop to create QR codes for user when they visit the page for the first time
    
    if (qr.length < 1 && <where I'd like to pass in the QR count based on tier>) {
        for (let i = qr.length; i < 6; i++) {
            const url = `https://${req.headers.host}/users/${user.id}/qr-` + (1 + i);
            const qrGenerator = await QRCode.toDataURL(url);
            const name = "qr-" + (1 + i);
            const qr = new Qr({
                user: user._id,
                url: url,
                qrcode: qrGenerator,
                name: name,
            });
            await qr.save();
        }
        res.render('users/activations', { activeEvents, qr, qrAgg });

    } else {
        res.render('users/activations', { activeEvents, qr, qrAgg });
    }
};

const priceToQrMappings = {
    price_id1: 2,
    price_id2: 7,
    price_id3: 10
   };