Retrieving sql queries from Active-record queries in Rails 3

问题

How do I trace which SQL query did my Activerecord methods generated (eg find, where).

回答1:

You can debug ActiveRecord queries from a console.

Hit rails console and enter:

ActiveRecord::Base.logger = Logger.new(STDOUT)

回答2:

I assume you're using Rails 3.0.x, you can do that by configuring your active record. Put this in config/environments/development.rb

# Log ActiveRecord
ActiveRecord::Base.logger = Logger.new(STDOUT) if defined?
Rails::Console

Now, every query is explained in console.

回答3:

You can call to_sql on relation objects (like that returned when you call where) to get the SQL for those queries.

回答4:

If you want to do it permanently (always show queries in console) just add those files:

~/.rvmrc

railsrc_path = File.expand_path('~/.railsrc')
if ( ENV['RAILS_ENV'] || defined? Rails ) && File.exist?( railsrc_path )
  begin
    load railsrc_path
  rescue Exception
    warn "Could not load: #{ railsrc_path }" # because of $!.message
  end
end

~/.railsrc

require 'active_record'

ActiveRecord::Base.logger = Logger.new(STDOUT)
ActiveRecord::Base.clear_active_connections!

来源：https://stackoverflow.com/questions/9173448/retrieving-sql-queries-from-active-record-queries-in-rails-3