Key Features of Enums #

Enums provide many built-in features that simplify coding and reduce boilerplate. Let’s go over some of them.

1. Automatic Query Methods #

When you define an enum, Rails automatically generates query methods for each value. Given:

class Post < ApplicationRecord
  enum :visibility, { draft: 0, published: 1, archived: 2 }
end

You can query posts like this:

Post.draft      # Returns all posts with visibility "draft"
Post.published  # Returns all posts with visibility "published"

This eliminates the need for manually defining scopes like:

scope :draft, -> { where(visibility: 0) }

2. Boolean Helper Methods #

Enums generate helper methods to check the current state of a record.

post = Post.new(visibility: :draft)
post.draft?      # => true
post.published?  # => false

3. State Transitions #

With a simple method call, you can update an Enum attribute.

post.published!  # Changes visibility to "published"

This eliminates the need for defining separate methods for updating states.

4. Using before_type_cast for Raw Values #

Sometimes, you may need to access the integer value of an Enum instead of its symbolic representation.

post = Post.new(visibility: :draft)
post.visibility_before_type_cast  # => 0

This is useful when working with APIs or raw database queries.