Rails validate uniqueness of date ranges

Question

I have an application that involves absence records for employees.

I need to ensure that the start and end dates for each record don\'t overlap.

So for example,

Answer 1

As a modification to the accepted answer, here's an overlaps scope that will work for DBs that don't understand DATEDIFF

  scope :overlaps, ->(start_date, end_date) do
    where "((start_date <= ?) and (end_date >= ?))", end_date, start_date
  end

This draws on the solution for Determine Whether Two Date Ranges Overlap

Answer 2

There is a gem called validates_overlap which allows you to easily validate date range overlaps. You can also use scopes on the validation.

Answer 3

Use the gem validates_overlap.

gem 'validates_overlap'

For example, if you have a model called Meeting with a start_date and end_date fields of type date, you can easily validate that they don't overlap.

class Meeting < ActiveRecord::Base
  validates :start_date, :end_date, overlap: true 
end

---

Another more realistic example, say a Meeting belongs_to a User, you can scope it out, so it only validates meetings for a particular user.

class Meeting < ActiveRecord::Base
  belongs_to User
  validates :start_date, :end_date, overlap: { scope: 'user_id',
                                             message_content: 'overlaps with Users other meetings.' }
end

Answer 4

I use these:

  scope :overlaps, ->(start_date, end_date) do
    where "(DATEDIFF(start_date, ?) * DATEDIFF(?, end_date)) >= 0", end_date, start_date
  end

  def overlaps?
    overlaps.exists?
  end

  # Others are models to be compared with your current model
  # you can get these with a where for example
  def overlaps
    siblings.overlaps start_date, end_date
  end

  validate :not_overlap

  def not_overlap
    errors.add(:key, 'message') if overlaps?
  end

  # -1 is when you have a nil id, so you will get all persisted user absences
  # I think -1 could be omitted, but did not work for me, as far as I remember
  def siblings
    user.absences.where('id != ?', id || -1)
  end

Source: https://makandracards.com/makandra/984-test-if-two-date-ranges-overlap-in-ruby-or-rails

Answer 5

While juanpastas solution is correct, it will be valid for creation of records, but can lead to false negative validations on updates.

If you need to edit an existing record, say the range is 2014-03-13..2014-06-12 and you want to reduce it to 2014-03-13..2014-04-12, you'll get an overlap error because it is checking AGAINST itself.

  def siblings
    Absence_users.where('user_id = ? AND id != ?', user_id, self)
  end

will obviate that shortcoming. (Dave T's addition should also be followed, being DB-agnostic.)