Enum validation in Ruby on Rails 7.1

The latest version of Rails, 7.1, introduces the ability to validate enums, enhancing data integrity and error handling in Rails models. Enums in Rails allow defining a set of permissible values for an attribute. Prior to Rails 7.1, assigning an invalid enum value would raise an ArgumentError, necessitating manual validation checks. The updated feature in Rails 7.1 streamlines this process by enabling built-in enum validation options within ActiveRecord objects.

Before Rails 7.1

class Project < ApplicationRecord
  enum status: [:active, :inactive, :archived] 
end

project = Project.find_by(name: "JT Project")

project.status = :new
=> `assert_valid_value': 'new' is not a valid status (ArgumentError)

To avoid ArgumentError exception, programmers used this trick:

project = Project.find_by(name: "JT Project")
status_value = :new

if Project.statuses[status_value].present?
  project.status = status_value
else
  # raise more consistent error than ArgumentError
end

After Rails 7.1

class Project < ApplicationRecord
  enum status: [:active, :inactive, :draft], validate: true 
end

project = Project.find_by(name: "JT Project")

project.status = :new # Now in this place we do not receive the error ArgumentError
project.valid?
=> false

Pay attention on validate: true in enum declaration.

We also can send additional rules to validation. For example:

validate: { allow_nil: true }

By leveraging the new enum validation feature in Rails 7.1, developers can ensure the integrity of enum attributes, streamline validation processes, and enhance the overall robustness of Rails applications.