Reservation Type System w/ Validation - Rails 3.0

Question

What would be the best approach to trying to "validate" uniqueness of dates for object.

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So for example, I have a Room, that can only have 1 person in it at a time.

A User can book this Room in advance.

Currently the Room is booked from the 1st of March to the 5th of March.

I want to prevent anyone from booking again on those dates.

So if someone attempts to book a room from the 25th of Feb to the 2nd of March, I need to tell them they cannot, because the room is fully booked.

--

I am using Rails 3.0

Answer 1

I just wrote a simple app to test this out. Here's what I ended up using in the model validation.

class Booking < ActiveRecord::Base
  validate :uniqueness_of_date_range

  private
  def uniqueness_of_date_range
    errors.add(:start_date, "is not available") unless Room.where("? >= start_date AND ? <= end_date",
                                                            start_date, start_date).count == 0
    errors.add(:end_date, "is not available") unless Room.where("? >= start_date AND ? <= end_date",
                                                            end_date, end_date).count == 0
  end
end

The first custom validation checks to see if the current record's start_date falls between the start_date and end_date of any record, and second one does the same for end_date. You might want to show a better error message (like what is the start/end date of the record(s) that is/are clashing with the current one by doing a similar query (using .all instead of .count, and adding all the details of matching rooms).

Here's the db migration I used

class CreateBookings < ActiveRecord::Migration
  def self.up
    create_table :bookings do |t|
      t.date :start_date
      t.date :end_date
      t.string :title

      t.timestamps
    end
  end

  def self.down
    drop_table :bookings
  end
end