Alex's Slip-box

These are my org-mode notes in sort of Zettelkasten style

ActiveRecord::Enum

Created on May 9, 2025

Updated on May 9, 2025

Tags: rails

See also https://api.rubyonrails.org/v8.0.0/classes/ActiveRecord/Enum.html See also ActiveRecord notes

I often use the following pattern with declaring an enum on an ActiveRecord model:

Migration: 

class AddStatusToGenerateImageRequests < ActiveRecord::Migration[7.2]
  def up
    add_column :generate_image_requests, :status, :text

    add_check_constraint :generate_image_requests, "status in ('created', 'queued', 'in_progress', 'failed', 'completed')", name: 'status_check'

    ActiveRecord::Base.connection.execute(<<~SQL)
      UPDATE generate_image_requests
      SET status = 'completed'
    SQL

    change_column_null :generate_image_requests, :status, false
  end

  def down
    remove_check_constraint :generate_image_requests, name: 'status_check'
    remove_column :generate_image_requests, :status
  end
end

In the model 

enum :status, {
  created: 'created',
  queued: 'queued',
  in_progress: 'in_progress',
  failed: 'failed',
  completed: 'completed'
}, default: 'created'

validates :status, inclusion: { in: statuses.values, message: "%<value>s must be one of #{statuses.values}" }
  • I like using strings for visibility and querying outside the context of the application
  • I’ll use check constraints to enforce proper values at the database layer. I don’t always do this. There are some cases where the enum list is expected to grow over time, like maybe a category or taxonomy in which case it’s a pain to have to create a migration every time.
  • Proper values also enforces at the model layer.
  • I might create an index if expected to query for records based on the enum value.

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