ActiveRecord::Undo

ActiveRecord::Undo brings transactional, cascade-aware soft deletes, instant single-line restores, and a mountable HTTP route engine to Ruby on Rails applications.

Unlike traditional soft-deletion gems that merely flip a timestamp on a single record, active_record-undo creates a polymorphic audit log capturing every affected child record across dependent: :destroy and dependent: :delete_all associations. Restoring a deleted record cleanly recovers the entire deleted subtree in a single atomic database transaction—with out-of-the-box support for multi-tenancy, user attribution, background purging, and zero-boilerplate HTTP endpoints.

• Features
• Installation & Migrations
  • Database Migrations
  • Model Setup
    • 1. Add Timestamp Column to Tables
    • 2. Declare acts_as_undoable
  • Basic Usage
    • Cascading Soft Deletes
    • Restoring Records
      • Option A: Restore from the model (Recommended)
      • Option B: Restore from the UndoLog
    • Status & Eligibility Helpers
    • Query Scopes
    • Inspecting Deletion Logs
  • Mountable Route & Controller Engine
    • Mounting the Engine
    • Available Endpoints
    • View Helpers (undo_button_to & undo_link_to)
    • Cryptographic Signed Restore Tokens
      • Generating & Using Signed Tokens
      • Key Security Properties
    • Multi-Format Responses
    • Security & Open-Redirect Protection
  • Multi-Tenant Isolation & User Attribution
    • User Attribution (whodunnit)
    • Multi-Tenant Scoping
    • Tenant Matching Security
    • Configured Context Enforcement
  • Retention, Expiration & Purging
    • Expiration Checks
    • Purger Service
    • ActiveJob Background Worker
    • Rake Task
  • Configuration Reference
  • How It Works
  • Error Reference
  • Development
  • Contributing
  • License

• 🔄 Cascading Soft Deletes: Soft deletes parent records along with dependent associations (dependent: :destroy / :delete_all).
• ⏪ Atomic Restores: Reverses soft deletion for an entire object tree (record.restore! or undo_log.restore!) within a single database transaction.
• 🌐 Mountable Engine & Endpoints: Out-of-the-box controller actions for instant undo links with HTML flash redirects, Turbo Streams, and JSON responses.
• 🔒 Cryptographic Signed Links: Direct undo restoration tokens (undo_log.signed_token) preventing ID enumeration on public or email links.
• 🎨 Clean View Helpers: Drop-in undo_button_to and undo_link_to view helpers for seamless UI integration.
• 🔍 Restoration Verification (#undoable?): Instantly check if a soft-deleted record is eligible for restore before rendering UI buttons.
• 👤 User Attribution (whodunnit): Tracks who initiated soft deletes and restores automatically via ambient context or explicit parameters.
• 🏢 Multi-Tenant Isolation: Scopes deletion logs to specific tenants with strict tenant-matching security.
• ⚙️ Custom Soft-Delete Columns: Supports custom columns (e.g., :archived_at, :discarded_at) per model while defaulting to :deleted_at.
• 🧹 Retention & Auto-Purging: Built-in expiration scopes, batch SQL purger, ActiveJob worker, and Rake task with foreign-key constraint protection.
• 🚂 Zero Generator Setup: Built as a Rails::Engine. Migrations automatically hook into rails db:migrate.

Add the gem to your application's Gemfile:

gem "active_record-undo"

Then install dependencies:

bundle install

ActiveRecord::Undo automatically appends its migrations (undo_logs and undo_log_items) to your application's migration path:

rails db:migrate

(Optional) If you plan to use Multi-Tenant Isolation or User Attribution, add the polymorphic columns to undo_logs:

# db/migrate/XXXXXX_add_tenant_and_whodunnit_to_undo_logs.rb
class AddTenantAndWhodunnitToUndoLogs < ActiveRecord::Migration[7.0]
  def change
    change_table :undo_logs, bulk: true do |t|
      t.string :whodunnit_type, null: true
      t.bigint :whodunnit_id, null: true
      t.string :tenant_type, null: true
      t.bigint :tenant_id, null: true
    end

    add_index :undo_logs, [:whodunnit_type, :whodunnit_id], name: "index_undo_logs_on_whodunnit"
    add_index :undo_logs, [:tenant_type, :tenant_id], name: "index_undo_logs_on_tenant"
  end
end

(Optional) If you wish to customize the gem's core migration directly:

rails active_record_undo:install:migrations

Ensure every model using soft deletion has a timestamp column:

class AddDeletedAtToModels < ActiveRecord::Migration[7.0]
  def change
    add_column :posts, :deleted_at, :datetime
    add_column :comments, :deleted_at, :datetime
    add_column :archive_items, :archived_at, :datetime

    add_index :posts, :deleted_at
    add_index :comments, :deleted_at
    add_index :archive_items, :archived_at
  end
end

Add acts_as_undoable to your models. By default, it uses the :deleted_at column:

class Post < ApplicationRecord
  acts_as_undoable

  has_many :comments, dependent: :destroy
end

class Comment < ApplicationRecord
  acts_as_undoable

  belongs_to :post
end

class ArchiveItem < ApplicationRecord
  # Configured with a custom timestamp column
  acts_as_undoable column: :archived_at
end

Call soft_delete! on any undoable record. It updates the timestamp column across the record and all dependent associations inside a single database transaction, returning an ActiveRecord::Undo::UndoLog instance:

post = Post.find(1)

# Soft deletes post and cascades to all associated comments
undo_log = post.soft_delete!

post.soft_deleted?       # => true
post.comments.kept.count # => 0

You can restore an entire deleted tree either from the model instance or from the UndoLog:

Calling restore! directly on the model automatically looks up its latest deletion log, executes the atomic restoration, destroys the log records, and reloads the model instance:

post.restore!

post.soft_deleted?  # => false
post.comments.count # => 2

undo_log.restore!

post.reload.soft_deleted? # => false

ActiveRecord::Undo provides fast predicate methods and audit helpers on models:

# Checks if the soft-delete column is set
post.soft_deleted? # => true / false

# Verifies record is soft-deleted AND has a valid undo log available in the database
post.undoable?     # => true / false

# Checks if the soft-deleted record has exceeded the configured retention period
post.expired?      # => true / false

# Retrieves the latest UndoLog audit record associated with this model
post.undo_log      # => #<ActiveRecord::Undo::UndoLog id: 14, ...>
post.latest_undo_log # alias

# Generates a cryptographic signed restoration token directly from the model
post.signed_token  # => "eyJfcmFpbHMiOnsiZGF0YSI6..."

<% if post.undoable? %>
  <%= undo_button_to(post, text: "Restore") %>
<% end %>

Filter records easily without writing manual SQL:

# Only active (non-deleted) records
Post.kept

# Only soft-deleted records
Post.soft_deleted

# Soft-deleted records past the retention limit
Post.expired

# Retrieve all records including soft-deleted ones
Post.unscoped.all

Inspect affected records through standard Rails associations on UndoLog:

undo_log.undo_log_items.map(&:item)
# => [#<Comment id: 101>, #<Comment id: 102>, #<Post id: 1>]

active_record-undo provides a mountable Rails engine route and controller endpoints so host applications can handle undo/restore actions via HTTP requests without writing boilerplate controller logic.

Mount the engine in your application routes:

# config/routes.rb
Rails.application.routes.draw do
  mount ActiveRecord::Undo::Engine => "/undo"
end

Clean view helpers are automatically available in all Rails views and forms:

<%# Standard button_to targeting /undo/logs/:id/restore %>
<%= undo_button_to(@undo_log) %>

<%# Pass model instances directly %>
<%= undo_button_to(post, text: "Undo Delete", class: "btn btn-primary") %>

<%# Secure direct link with signed token (prevents ID enumeration in emails or public links) %>
<%= undo_button_to(@undo_log, signed: true, class: "btn btn-success") %>

<%# Turbo Stream / Hotwire compatible link %>
<%= undo_link_to(@undo_log, text: "Undo", class: "text-decoration-underline") %>
<%= undo_link_to(@undo_log, signed: true) %>

When exposing restore actions in flash notifications, transactional emails, webhook alerts, or public interfaces, relying on sequential database IDs (e.g., POST /undo/logs/42/restore) can expose your application to ID enumeration attacks.

active_record-undo provides signed tokens for restoration via tamper-proof, opaque URLs: POST /undo/restore/:token.

In Views (using helpers):

<%# Renders a form POST to /undo/restore/:token %>
<%= undo_button_to(post, signed: true, text: "Undo Delete", class: "btn btn-outline-primary") %>

<%# Renders an anchor tag for Turbo / Hotwire %>
<%= undo_link_to(post, signed: true, text: "Undo") %>

In Controllers, Background Jobs & Mailers:

# Generate token directly from the model instance
token = post.signed_token

# Or with a custom expiration window
token = post.signed_token(expires_in: 2.hours)

# Or directly from an UndoLog instance
token = undo_log.signed_token

# Construct full URL for transactional emails or Slack webhooks
restore_url = active_record_undo.signed_restore_url(token: token)

Manual Verification & Retrieval:

# Manually verify and retrieve the associated UndoLog
undo_log = ActiveRecord::Undo::UndoLog.find_by_signed_token(params[:token])

1. HMAC-SHA256 Cryptographic Tamper Resistance: Tokens are signed using Rails.application.message_verifier(:active_record_undo) derived securely from your application's secret_key_base. Any payload alteration invalidates the cryptographic signature.
2. Purpose Isolation (purpose: :restore): Tokens are strictly scoped to restoration. Tokens generated for other purposes (or by other verifiers) are rejected.
3. Time-Limited Lifespan: Tokens include an embedded expiration timestamp (configurable via config.token_expires_in, defaults to 24.hours). Expired tokens are rejected automatically.
4. Single-Use Replay Protection: When undo_log.restore! succeeds, it automatically destroys the UndoLog and its associated items from the database (destroy!). Even if an attacker or user resubmits the signed token before its cryptographic expiration, the database lookup fails and returns nil, rendering a 404 Not Found.
5. Multi-Tenant Authorization: Cryptographic validity only proves the token was authentic. During execution, undo_log.restore! still enforces multi-tenant boundary matching against ActiveRecord::Undo.current_tenant. An authenticated user from Tenant B cannot use a token from Tenant A to restore data.

The engine controller seamlessly handles multiple response formats:

• HTML: Redirects to params[:redirect_to] (if a validated safe URL), request.referer, or config.default_redirect_path with a flash notice (flash[:notice] = "Record successfully restored.").
• Turbo Stream (text/vnd.turbo-stream.html): Renders inline <turbo-stream> notification elements with HTTP status 200 OK.
• JSON: Returns { "success": true, "restored_items_count": count } with HTTP status 200 OK.

In error scenarios (missing record, expired action, or security mismatch):

• 403 Forbidden: Rendered on ActiveRecord::Undo::SecurityError (or HTML redirected with flash[:alert]).
• 404 Not Found: Rendered when the undo log does not exist or has already been restored.
• 422 Unprocessable Content: Rendered when the undo action has expired beyond the retention period.

• CSRF Protection: Inherits from ActionController::Base (or your configured base_controller) with CSRF verification enabled.
• Open-Redirect Mitigation: params[:redirect_to] and request.referer undergo strict URL validation. Only relative paths or URLs matching the request's exact host and port are accepted; foreign or protocol-relative URLs (e.g., //evil.com) are rejected in favor of the safe fallback.
• Signed Tokens: undo_log.signed_token uses Rails' message_verifier(:active_record_undo) to sign tokens cryptographically, preventing tampering, replay, and ID enumeration.

To support enterprise-grade Rails applications, active_record-undo natively integrates user auditing and tenant scoping.

Track which user initiated a soft deletion or restoration:

# 1. Via explicit parameter
post.soft_delete!(whodunnit: current_user)
post.restore!(whodunnit: current_user)

# 2. Via Thread / Fiber ambient context
ActiveRecord::Undo.whodunnit = current_user
post.soft_delete!

# 3. Via global callable proc
ActiveRecord::Undo.configure do |config|
  config.current_user_method = -> { Current.user }
end

Scope soft deletes and logs to accounts or organizations:

# 1. Via explicit parameter
post.soft_delete!(tenant: current_account)

# 2. Via Thread / Fiber ambient context
ActiveRecord::Undo.current_tenant = current_account
post.soft_delete!

# 3. Via global callable proc
ActiveRecord::Undo.configure do |config|
  config.current_tenant_method = -> { Current.account }
end

When restoring a log belonging to a tenant, the gem verifies that the executing context's tenant matches the log's tenant. If there is a mismatch or missing tenant context, an ActiveRecord::Undo::SecurityError is raised:

ActiveRecord::Undo.current_tenant = wrong_account
post.restore! # => raises ActiveRecord::Undo::SecurityError (Tenant mismatch)

When current_user_method or current_tenant_method is configured via ActiveRecord::Undo.configure, operations ensure the context does not evaluate to nil:

# If current_user_method evaluates to nil (e.g., unauthenticated request):
post.soft_delete! # => raises ActiveRecord::Undo::SecurityError: Configured current_user_method returned nil.

(If neither method is configured, operations proceed normally without requiring user or tenant context).

To keep your database lean, active_record-undo provides retention management and automated background purging.

Query and check expired records using the configured retention window (default: 30.days):

# Scopes
Post.expired                        # Soft-deleted posts older than retention period
ActiveRecord::Undo::UndoLog.expired # Undo logs older than retention period

# Predicates
post.expired?     # => true / false
undo_log.expired? # => true / false

ActiveRecord::Undo::Purger performs batch SQL deletes bypassing model callbacks for peak efficiency:

# Purge all expired records and logs across registered models
ActiveRecord::Undo::Purger.purge_expired!(batch_size: 1000)

# Scoped purge for a specific tenant
ActiveRecord::Undo.current_tenant = account_1
ActiveRecord::Undo::Purger.purge_expired!

Enqueue purges easily via ActiveJob:

ActiveRecord::Undo::PurgeJob.perform_later(batch_size: 1000)

Run purging from cron, cron-like schedulers, or CI:

# Default batch size (1000)
rails active_record_undo:purge_expired

# Custom batch size
BATCH_SIZE=500 rails active_record_undo:purge_expired

Configure all gem options in a single initializer:

# config/initializers/active_record_undo.rb
ActiveRecord::Undo.configure do |config|
  # Default retention period for soft-deleted records and undo logs (defaults to 30.days)
  # Set to nil to disable expiration
  config.retention_period = 30.days

  # Callable procs to resolve ambient user and tenant context (defaults to nil)
  config.current_user_method   = -> { Current.user }
  config.current_tenant_method = -> { Current.account }

  # Base controller for engine authentication and authorization hooks
  # Defaults to "::ApplicationController" if defined, falling back to ActionController::Base
  config.base_controller = "::ApplicationController"

  # Fallback redirect path after successful restore when no redirect_to or referer exists
  config.default_redirect_path = ->(main_app) { main_app.root_path }

  # Expiration duration for signed restore tokens (defaults to 24.hours)
  config.token_expires_in = 24.hours

  # Custom secret key for signed tokens (defaults to nil, utilizing Rails application verifier)
  config.token_secret_key = nil

  # Error handling strategy for HTML requests (:auto, :redirect, or :render)
  # Defaults to :auto (redirects with flash alert if referer/redirect_to present, else renders status)
  config.error_handling = :auto
end

1. Cascade Inspection: On calling soft_delete!, ActiveRecord::Undo::CascadeHandler reflects on has_many, has_one, and belongs_to associations configured with dependent: :destroy or :delete_all.
2. Column Resolution: Identifies record.class.undoable_column to apply the correct timestamp column (:deleted_at, :archived_at, etc.) across all affected models.
3. Audit Logging: Creates an UndoLog and individual UndoLogItem entries storing polymorphic references (item_type, item_id) for every soft-deleted record.
4. Atomic Operation: Deletions and log creations execute within a single ActiveRecord::Base.transaction.
5. Reverse Restoration: Calling restore! executes within a transaction, iterating over items in reverse order (reverse_each) so parent and dependent records are re-activated in the proper sequence before purging the log.

Clone the repository and install dependencies:

git clone https://github.com/saurabh-activecode/active_record-undo.git
cd active_record-undo
bundle install

Run test suite via RSpec:

bundle exec rspec

Run RuboCop linting:

bundle exec rubocop

Bug reports and pull requests are welcome on GitHub at https://github.com/saurabh-activecode/active_record-undo.

The gem is available as open source under the terms of the MIT License.