ActiveRecord Extras

ActiveRecord Extras provides helpful utility methods and query extensions for ActiveRecord models. It focuses on building SQL subqueries for has_many associations using EXISTS and COUNT, while keeping full composability within ActiveRecord queries.

Features

  • exists_association and count_association methods for Arel-based subqueries
  • Scopes:
    • with_existing(:association)
    • without_existing(:association)
  • Extended select support:
    • with_counts(:association) — includes counts in result sets
    • Accepts optional block for filtering join conditions
  • Fully composable ActiveRecord relations
  • No monkey-patching, Rails 6+ compatible

Installation

Add to your Gemfile:

gem "activerecord_extras"

Then run:

bundle install

Or install manually:

gem install activerecord_extras

Usage

with_existing and without_existing

User.with_existing(:posts)
User.without_existing(:comments)

with_counts

Adds a SELECT COUNT(*) subquery per association:

User.with_counts(:posts)

Supports filtering via block:

User.with_counts(:posts) do |join_condition, posts|
  join_condition.and(posts[:published].eq(true))
end

This produces SQL like:

SELECT users.*, (
  SELECT COUNT(*) FROM posts
  WHERE posts.user_id = users.id AND posts.published = TRUE
) AS posts_count

API Reference

exists_association(association_name, &block)

Returns an Arel EXISTS subquery.

count_association(association_name, &block)

Returns a grouped COUNT(*) Arel subquery.

with_counts(*association_names, &block)

Selects all columns from the model and adds one COUNT subquery per named association. The optional block modifies join conditions.

Development

bundle exec rake test

Tests use SQLite in-memory schema and require no database setup.

License

MIT License © Till Schulte-Coerne