Arboreal is yet another extension to ActiveRecord to support tree-shaped data structures. Internally, Arboreal maintains a computed "ancestry_string" column, which caches the path from the root of a tree to each node, allowing efficient retrieval of both ancestors and descendants. Arboreal surfaces relationships within the tree like "children", "ancestors", "descendants", and "siblings" as scopes, so that additional filtering/pagination can be performed.

Arca is a callback analyzer for ActiveRecord ideally suited for digging yourself out of callback hell

Parameter filter done OO, extending strong parameters.

Archive your Rails models rather than delete them, with model and controller concerns.

ArchiveTree is a Ruby Gem that makes it easy for you to create beautiful chronological archive trees of your models. For instance, you can create a tree for your blog posts.

This is a functional replacement for acts_as_archive in rails 3 applications, the only functionality that is not duplicated is the migration from acts_as_paranoid

Extends ActiveRecord functionality by adding better finder/query support, as well as supporting mass data import, foreign key, CSV and temporary tables

Merge 2 ActiveRecords, preserving associations and attributes

Fast access to database results without the memory overhead of ActiveRecord objects

Easing the query object pattern in Rails applications.

Add simple finegrained handcontrolled identity map for ActiveRecord

ActiveRecord data synchronized with frontend DataStore

Override migration methods to support UUID columns without having to be explicit about it.

Add sorting scopes `asc` and `desc` to your ActiveRecord models.

Access mysql without blocking.

An ActiveRecord extension for writing commonly useful atomic SQL statements to avoid race condition.

This plugin implements attachment storage and processing, integrated with ActiveRecord models and Ruby CGI/Rails-style uploads. Image processing operations including a number of different resizing & thumbnailing modes are provided, and the architecture simplifies clean implementation of other types of processing. Errors are carefully handled to minimize the possibility of broken uploads leaving incomplete or corrupt data. RMagick, MiniMagick, and ImageScience image processors are supported.

Changes behavior of Active Record present?

Store a few extra (non-searchable) attributes away in a bucket. This is probably a horrible idea, but try it anyway.

A simple and non-intrusive way to mark deprecated columns/attributes in your models. Any usage of these attributes will logged with a warning message and a trace of where the deprecated attribute was called. An exception can be optionally raised as well.