lazy loaded porperties cause .save failure even if you don't touch that property.

[MarcWeber]

sample code derived from http://datamapper.org/docs/create_and_destroy.html,
When you run it the second time you'll get the error:

/pr/tasks/ruby/datamapper/dm/dm-core/lib/dm-core/property.rb:712:in `assert_valid_value': Invalid value nil for property :body (DataMapper::Property::Text) on model Post (DataMapper::Property::InvalidValueError)

CODE:

# encoding: UTF-8
require 'dm-core'

$DATA_MAPPER_MYSQL_CONNECTION = 'mysql://root:mysqlpage@localhost/datamapper'

# If you want the logs displayed you have to do this before the call to setup
DataMapper::Logger.new($stdout, :debug)

DataMapper.setup(:default, $DATA_MAPPER_MYSQL_CONNECTION )

# by default all fields are required
DataMapper::Property.required(true)
DataMapper::Property::String.length(120)
DataMapper::Property::Boolean.allow_nil(false)
DataMapper::Model.raise_on_save_failure = true

class Post
  include DataMapper::Resource

  property :id, Serial
  property :title, String
  property :body, Text

end

DataMapper.finalize

require  'dm-migrations'
DataMapper.auto_upgrade!

if Post.first
  puts "phase2 editing post"
  post = Post.first
  post.title = "dummy"
  # this causes an exception because body porperty is nil because its loaded lazily !?
  post.save
else
  puts "creating post, rerun script!"
  post = Post.create({
    :title =>  "My first DataMapper post",
    :body => "A lot of text ...",
  })
end

# repository(:default).adapter.execute('COMMIT')

This causes the feeling that the mysql backend (and maybe all?) are still kind of unstable.

Tell me if I should file this bug against a different github repo.. maybe its not related to mysql at all.