How to use an enum value in an :if validation

Question

Suppose that we have an enum

enum status: { pending: 0, finished: 1, extended: 2 }

And we want to create a validation based on the value of the enum status

validates_presence_of :explanation, if: ...enum status is equal to "extended"

I've been brute force, trying many combinations but can't seem to find anything that works.

Answer 1

You can evaluate your field using pending?

class Job < ActiveRecord::Base
  enum status: [ :active, :archived ]
  validates_presence_of :explanation, if: Proc.new { |a| a.extended? }
end

Complete example :

class Conversation < ActiveRecord::Base
  enum status: [ :active, :archived ]
end

# conversation.update! status: 0
conversation.active!
conversation.active? # => true
conversation.status  # => "active"

# conversation.update! status: 1
conversation.archived!
conversation.archived? # => true
conversation.status    # => "archived"

# conversation.status = 1
conversation.status = "archived"

conversation.status = nil
conversation.status.nil? # => true
conversation.status      # => nil

Reference:
http://api.rubyonrails.org/classes/ActiveRecord/Enum.html

Answer 2

Short version:

validates_presence_of :explanation, if: 'extended?'