Is there a print_r or var_dump equivalent in Ruby / Ruby on Rails?

Question

I'm looking for a way to dump the structure of an object, similar to the PHP functions print_r and var_dump for debugging reasons.

Answer 1

In views:

DebugHelper’s debug(object)

In controllers, models, and other code:

puts YAML::dump(object)

Source

Answer 2

The .inspect method of any object should format is correctly for display, just do..

<%= theobject.inspect %>

The .methods method may also be of use:

<%= theobject.methods.inspect %>

It may help to put that in <pre> tags, depending on the data

Answer 3

If you just want the relevant data to be displayed to stdout (the terminal output if you're running from the command line), you can use p some_object.

Answer 4

In a view you can use <%= debug(yourobject) %> which will generate a YAML view of your data. If you want something in your log you should use logger.debug yourobject.inspect.

Answer 5

You can also use YAML::dump shorthand (y) under Rails console:

>> y User.first
--- !ruby/object:User 
attributes: 
  created_at: 2009-05-24 20:16:11.099441
  updated_at: 2009-05-26 22:46:29.501245
  current_login_ip: 127.0.0.1
  id: "1"
  current_login_at: 2009-05-24 20:20:46.627254
  login_count: "1"
  last_login_ip: 
  last_login_at: 
  login: admin
attributes_cache: {}

=> nil
>>

If you want to just preview some string contents, try using raise (for example in models, controllers or some other inaccessible place). You get the backtrace for free:)

>> raise Rails.root
RuntimeError: /home/marcin/work/github/project1
    from (irb):17
>>

I also really encourage you to try ruby-debug:

• http://railscasts.com/episodes/54-debugging-with-ruby-debug
• http://www.sitepoint.com/article/debug-rails-app-ruby-debug/
• http://www.datanoise.com/articles/2006/7/12/tutorial-on-ruby-debug

It's incredibly helpful!

Answer 6

I use this :)

require 'yaml'

module AppHelpers

module Debug

 module VarDump

  class << self

   def dump(dump_object, file_path)

    File.open file_path, "a+" do |log_file|
     current_date = Time.new.to_s + "\n" + YAML::dump(dump_object) + "\n"
     log_file.puts current_date
     log_file.close
    end
   end

  end

 end

end

end