How can I see the SQL that will be generated by a given ActiveRecord query in Ruby on Rails

Question

I would like to see the SQL statement that a given ActiveRecord Query will generate. I recognize I can get this information from the log after the query has been issued, but I'm wondering if there is a method that can be called on and ActiveRecord Query.

For example:

SampleModel.find(:all, :select => "DISTINCT(*)", :conditions => ["`date` > #{self.date}"], :limit => 1, :order => '`date`', :group => "`date`") 

I would like to open the irb console and tack a method on the end that would show the SQL that this query will generate, but not necessarily execute the query.

Answer 1

Similar to penger's, but works anytime in the console even after classes have been loaded and the logger has been cached:

For Rails 2:

ActiveRecord::Base.connection.instance_variable_set :@logger, Logger.new(STDOUT) 

For Rails 3.0.x:

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

For Rails >= 3.1.0 this is already done by default in consoles. In case it's too noisy and you want to turn it off you can do:

ActiveRecord::Base.logger = nil 

Answer 2

Stick a puts query_object.class somewhere to see what type of object your working with, then lookup the docs.

For example, in Rails 3.0, scopes use ActiveRecord::Relation which has a #to_sql method. For example:

class Contact < ActiveRecord::Base   scope :frequently_contacted, where('messages_count > 10000') end 

Then, somewhere you can do:

puts Contact.frequently_contacted.to_sql