ransack

https://github.com/activerecord-hackery/ransack

Ruby

Object-based searching.

Ransack::Adapters::ActiveRecord::Context#build_correlated_subquery

Build an Arel subquery that selects keys for the top query,
drawn from the first join association's foreign_key.

Example: for an Article that has_and_belongs_to_many Tags

  context = Article.search.context
  attribute = Attribute.new(context, "tags_name").tap do |a|
    context.bind(a, a.name)
  end
  context.build_correlated_subquery(attribute.parent).to_sql

  # SELECT "articles_tags"."article_id" FROM "articles_tags"
  # INNER JOIN "tags" ON "tags"."id" = "articles_tags"."tag_id"
  # WHERE "articles_tags"."article_id" = "articles"."id"

The WHERE condition on this query makes it invalid by itself,
because it is correlated to the primary key on the outer query.

Source | Google | Stack overflow

Edit

git clone [email protected]:activerecord-hackery/ransack.git

cd ransack

open lib/ransack/adapters/active_record/context.rb

Contribute

# Make a new branch

git checkout -b -your-name--update-docs-Ransack--Adapters--ActiveRecord--Context-build_correlated_subquery-for-pr

# Commit to git

git add lib/ransack/adapters/active_record/context.rbgit commit -m "better docs for Ransack::Adapters::ActiveRecord::Context#build_correlated_subquery"

# Open pull request

gem install hub # on a mac you can `brew install hub`

hub fork

git push <your name> -your-name--update-docs-Ransack--Adapters--ActiveRecord--Context-build_correlated_subquery-for-pr

hub pull-request

# Celebrate!