order_test.rb

#!/usr/bin/env ruby -Ku
 
require 'rubygems'
require 'dm-core'
 
DataMapper::Logger.new($stdout, :debug)
DataMapper.setup(:default, 'mysql://localhost/testdb')
 
class User
  include DataMapper::Resource
 
  property :id, Serial
  property :age, Integer
  property :name, String
end

DataMapper.auto_migrate!

User.create(:name => 'Bob', :age => 34)
User.create(:name => 'Mary', :age => 27)
User.create(:name => 'Jack', :age => 53)
User.create(:name => 'Jill', :age => 22)

s = User.all(:order => [:age.asc])
puts s.map{|r| r.name}     # => Jill Mary Bob Jack  -- ok
puts s.last.name           # => Jack                -- ok
puts s.map{|r| r.name}     # => Jill Mary Bob Jack  -- ok

s = User.all(:order => [:age.asc])
puts s.last.name           # => Jack                -- ok
puts s.map{|r| r.name}     # => Bob Mary Jill Jack  -- huh?