Datamapper DataMapper

Forgive me for having to double-space this ticket.... everything got wrapped all crazy (who cares about newlines, right?)

At first, I believed this issue was restricted to just the DataMapper::Types::Object class, however it seems to occur in others. It seems that if you define a default value for a property, the default value is only every instantiated once... Direct modifications to the object stored by the property will occur across every object... This is more prevalent in things like hashes and arrays, for which direct object operations are expected... However, it is observable in Strings as well... I'm sure it could be demonstrated for many more...

require 'rubygems'
require 'dm-core'

class Testy
include DataMapper::Resource

property :id, Serial

property :stringy, String, :default => "asdf"

property :hashy, Object, :default => {}

end

DataMapper.setup(:default, "sqlite3::memory:")

DataMapper.auto_migrate!(:default)

test1 = Testy.create

test2 = Testy.create

test1.stringy[0] = "X"

test1.hashy["himom"] = 9999

puts "test1 (#{test1.id}) hashy object id: #{test1.hashy.object_id}, himom: #{test1.hashy["himom"].inspect}"

puts "test2 (#{test2.id}) hashy object id: #{test2.hashy.object_id}, himom: #{test2.hashy["himom"].inspect}"

puts "test1 (#{test1.id}) stringy object id: #{test1.stringy.object_id}, value #{test1.stringy.inspect}"

puts "test2 (#{test2.id}) stringy object id: #{test2.stringy.object_id}, value #{test2.stringy.inspect}"

Output:

test1 (1) hashy object id: 9480490, himom: 9999

test2 (2) hashy object id: 9480490, himom: 9999

test1 (1) stringy object id: 9482920, value "Xsdf"

test2 (2) stringy object id: 9482920, value "Xsdf"

So, yeah.... This made for some confusion on my part, however it totally makes sense, now. Wrapping the default value in lambda {} will cause my value to get evaluated each time the default is set, and this gets me the kind of behavior I expect to see:

require 'rubygems'

require 'dm-core'

class Testy

include DataMapper::Resource

property :id, Serial

property :stringy, String, :default => lambda { "asdf" }

property :hashy, Object, :default => lambda { {} }

end

DataMapper.setup(:default, "sqlite3::memory:")

DataMapper.auto_migrate!(:default)

test1 = Testy.create

test2 = Testy.create

test1.stringy[0] = "X"

test1.hashy["himom"] = 9999

puts "test1 (#{test1.id}) hashy object id: #{test1.hashy.object_id}, himom: #{test1.hashy["himom"].inspect}"

puts "test2 (#{test2.id}) hashy object id: #{test2.hashy.object_id}, himom: #{test2.hashy["himom"].inspect}"

puts "test1 (#{test1.id}) stringy object id: #{test1.stringy.object_id}, value #{test1.stringy.inspect}"

puts "test2 (#{test2.id}) stringy object id: #{test2.stringy.object_id}, value #{test2.stringy.inspect}"

Output:

test1 (1) hashy object id: 9468380, himom: 9999

test2 (2) hashy object id: 9466410, himom: nil

test1 (1) stringy object id: 9468510, value "Xsdf"

test2 (2) stringy object id: 9466620, value "asdf"