Method: ActiveRecord::QueryMethods::WhereChain#associated

Defined in:

lib/active_record/relation/query_methods.rb

#associated(*associations) ⇒ Object

Returns a new relation with joins and where clause to identify associated relations.

For example, posts that are associated to a related author:

Post.where.associated(:author)
# SELECT "posts".* FROM "posts"
# INNER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# WHERE "authors"."id" IS NOT NULL

Additionally, multiple relations can be combined. This will return posts associated to both an author and any comments:

Post.where.associated(:author, :comments)
# SELECT "posts".* FROM "posts"
# INNER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# INNER JOIN "comments" ON "comments"."post_id" = "posts"."id"
# WHERE "authors"."id" IS NOT NULL AND "comments"."id" IS NOT NULL

# File 'lib/active_record/relation/query_methods.rb', line 69

def associated(*associations)
  associations.each do |association|
    reflection = scope_association_reflection(association)
    @scope.joins!(association)
    self.not(reflection.table_name => { reflection.association_primary_key => nil })
  end

  @scope
end