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