A simple rails concern for checking if a record is referenced in some foreign_key (by id)

foreign_keys_check.rb

module ForeignKeysCheck
  extend ActiveSupport::Concern

  def has_foreign_key_references?
    self.class.all_constraints.group_by {|c| c["table_name"] }.each do |table_name, constraints|
      check_query = "SELECT 1 from #{table_name} WHERE "
      check_query << constraints.map { |d| "#{d['column_name']} = #{self.id}" }.join(' OR ')
      result = ActiveRecord::Base.connection.execute(check_query)
      result.count
      return true if result.count > 0
    end
    false
  end

  class_methods do

    def all_constraints
      @all_constraints ||= ActiveRecord::Base.connection.execute <<-SQL
        SELECT
          tc.table_schema, tc.constraint_name, tc.table_name, kcu.column_name, ccu.table_name
          AS foreign_table_name, ccu.column_name AS foreign_column_name
        FROM
          information_schema.table_constraints tc
          JOIN information_schema.key_column_usage kcu
            ON tc.constraint_name = kcu.constraint_name
          JOIN information_schema.constraint_column_usage ccu
            ON ccu.constraint_name = tc.constraint_name
        WHERE constraint_type = 'FOREIGN KEY' AND ccu.table_name = '#{self.table_name}'
      SQL
    end

  end
end