Make debugging a bit easier by determining the source of ActiveRecord queries. The source of queries will be output via logger.debug().

query_source.rb

#
# Make debugging a bit easier by determining the source of ActiveRecord queries.
# The source of queries will be output via logger.debug().
#
# By: Skye Shaw (https://github.com/sshaw)
# Date: 2014-10-24
# Source: https://gist.github.com/sshaw/05d8bdf99e4175816db858323fb2169c
#
# === Usage
#
#  # ActiveSupport::BacktraceCleaner
#  QuerySource::STACK_CLEANER.add_silencer { |line| line =~ /foo/ }
#
#  # Trace all User queries
#  User.extend QuerySource
#
#  # Trace all ActiveRecord queries
#  ActiveRecord::Base.extend QuerySource
#

module QuerySource
  START_TRACE_MARKER = " Begin Query Trace ".center(50, "=").freeze
  END_TRACE_MARKER = " End Query Trace ".center(50, "=").freeze

  STACK_CLEANER = if defined?(Rails)
                    Rails.backtrace_cleaner
                  else
                    require "active_support/backtrace_cleaner"
                    cleaner = ActiveSupport::BacktraceCleaner.new
                    cleaner.add_silencer { |line| line =~ %r(/gems/) }
                  end


  def find_by_sql(req, sql)
    return super unless logger.debug?

    trace = STACK_CLEANER.clean(caller)
    return super unless trace.any?

    logger.debug(START_TRACE_MARKER)

    result = super

    logger.debug(trace.join("\n"))
    logger.debug(END_TRACE_MARKER)

    result
  end
end