Question

How can I dry up my validation code? I have a Discussion model that has a a category and status fields. The status value depends on the category value. A discussion where category == 'question' can only have a status in STATUSES[:question], for example.

  STATUSES   = {
    question:   %w[answered],
    suggestion: %w[pending planned started completed declined],
    problem:    %w[started solved]
  }
  validates :status, allow_blank: true, inclusion: { in: STATUSES[:question] },   if: lambda { self.category == 'question' }
  validates :status, allow_blank: true, inclusion: { in: STATUSES[:suggestion] }, if: lambda { self.category == 'suggestion' }
  validates :status, allow_blank: true, inclusion: { in: STATUSES[:problem] },    if: lambda { self.category == 'problem' }

I’m using Rails 3.

Answer 1

:inclusion :in accepts a lambda itself:

validates :status, inclusion: { in: lambda { |o| STATUSES[o.category.to_sym] } }

Documentation: http://apidock.com/rails/ActiveModel/Validations/HelperMethods/validates_inclusion_of