Suppose I have a very simple array like this totalSpots = [95] and it has only one value. Now a new booking is created and I want to automatically assign 1 parking-spot to the user whoever booked it and reduce array's value by 1 or whatever the user enter to make it [94] or [95 - user_request_number]

Below is the query to create a booking:

exports.createBooking = async (req, res) => {
  try {
    const user = await Auth.findOne({ _id: req.data.id });
    if (!user) return res.status(404).json({ error: "User not found" });

    const { parkingId, date, startTime } = req.body;
    
    const parking = await Parking.findOne({ _id: parkingId, date });

    if (!parking)
      return res.status(404).json({ error: "Parking details not available" });

    const bookingDetails = new Booking({
      user,
      parking,
      startTime,
      duration: req.body.duration,
      date: moment(req.body.date).format("MMM DD, YYYY"),
      endTime: req.body.endTime,
      paymentAmount: req.body.paymentAmount,
      isFeePaid: req.body.isFeePaid,
      status: "sent",
    });

    const save = await bookingDetails.save();

    return res.status(200).json({
      success: true,
      msg: "Service Booked",
      data: { details: save },
    });
  } catch (error) {
    return res.status(500).json({ error: error.message });
  }
};

Currently I am not focusing on taking a spot values from users but I will do in the future.

And when a consumer removes his vehicle from that place, I want to increase a value as well, but not higher than the totalSpots that the merchant has set.

I am storing totalSpots as an array because in the future the value could be like this totalSpots = [1, 2, 3 ...upto 95]