Hashie Data Mapper 
An extension to the Hashie Ruby Gem for Working with Data Mappers.
This is hopefully just a temporary project, pending the merge into Hashie of this pull request: hashie/hashie#131
Installation
Add this to your Gemfile:
gem 'hashie_data_mapper', '~> 0.1.4'
Usage
require 'hashie'
require 'hashie_data_mapper'
class Person < Trash
include HashieDataMapper::IgnoreUndeclared
property :first_name
property :last_name
end
user_data = {
:first_name => 'Freddy',
:last_name => 'Nostrils',
:email => 'freddy@example.com'
}
p = Person.new(user_data) # 'email' is silently ignored
p.first_name # => 'Freddy'
p.last_name # => 'Nostrils'
p.email # => NoMethodError