Ruby on Rails
DebugWithYAML

Rails include YAML.rb somewhere, so we have access to the to_yaml method on any object.

To see what’s in an object, define a helper:

def dump(object)
  "<pre>" << object.to_yaml << "</pre>" 
end

Then in your rhtml, you can do a:

<%= dump @person %>
<%= dump @person.methods.sort %>

Which may yield something like:

--- &id001 !ruby/object:Person 
attributes: 
  name: Superman
  city: Smallville
  zip: "12345" 
  street1: PO Box 123
  street2: 123 Somewhere
  id: 1
  state: KS
errors: !ruby/object:ActiveRecord::Errors 
  base: *id001
  errors: {}
phones: 
  - !ruby/object:Phone 
    attributes: 
      id: "1" 
      phone: "6203423065" 
      person_id: "1" 
  - !ruby/object:Phone 
    attributes: 
      id: "2" 
      phone: "6204811303" 
      person_id: "1"