dm2.rb

#!/usr/bin/env ruby

$: << '~/project/merb/dm/specs/dm-core/lib'
require 'dm-core'
 
DataMapper::Logger.new(STDOUT, :debug)
DataMapper.setup(:default, 'sqlite3::memory:')
 
class Article
  include DataMapper::Resource
  property :id, Serial
  property :title, String
end
  
DataMapper.auto_migrate!

# setup

@article_repository = repository(:default)
@model              = Article
@articles_query     = DataMapper::Query.new(@article_repository, @model, :title => 'Sample Article')
@article            = @model.create(:title => 'Sample Article')
@other              = @model.create(:title => 'Other Article')
@articles           = @model.all(@articles_query)

# test
puts "#{@articles.size} articles"
@return = @articles.slice!(2, 2)
puts "@return = nil" if @return.nil?
@articles.dup.destroy!

Output

Wed, 29 Oct 2008 04:25:11 GMT ~ debug ~ DROP TABLE IF EXISTS "articles"
Wed, 29 Oct 2008 04:25:11 GMT ~ debug ~ PRAGMA table_info('articles')
Wed, 29 Oct 2008 04:25:11 GMT ~ debug ~ SELECT sqlite_version(*)
Wed, 29 Oct 2008 04:25:11 GMT ~ debug ~ CREATE TABLE "articles" ("id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, "title" VARCHAR(50))
Wed, 29 Oct 2008 04:25:11 GMT ~ debug ~ INSERT INTO "articles" ("title") VALUES ('Sample Article')
Wed, 29 Oct 2008 04:25:11 GMT ~ debug ~ INSERT INTO "articles" ("title") VALUES ('Other Article')
Wed, 29 Oct 2008 04:25:11 GMT ~ debug ~ SELECT "id", "title" FROM "articles" WHERE ("title" = 'Sample Article') ORDER BY "id"
1 articles
@return = nil
Wed, 29 Oct 2008 04:25:11 GMT ~ debug ~ DELETE FROM "articles" WHERE ("title" = 'Sample Article') AND ("id" IN (1))
/Users/copa/project/merb/dm/specs/dm-core/lib/dm-core/collection.rb:579:in `destroy!': undefined method `key' for nil:NilClass (NoMethodError)
        from /usr/local/lib/ruby/gems/1.8/gems/extlib-0.9.8/lib/extlib/lazy_array.rb:15:in `each'
        from /usr/local/lib/ruby/gems/1.8/gems/extlib-0.9.8/lib/extlib/lazy_array.rb:15:in `each'
        from /Users/copa/project/merb/dm/specs/dm-core/lib/dm-core/collection.rb:576:in `destroy!'
        from dm2.rb:31