#738 ✓resolved
Brian Terlson

dm-is-list position updates behave strangely when position is beyond list bounds

Reported by Brian Terlson | January 2nd, 2009 @ 01:10 PM | in 0.10.0

You can set the position attribute of a list item to be less than the specified starting position, but not more than the maximum position. Either direct positional updates should not be checked at all, or, ideally, both min and max bounds should be checked.

What's more, moving a list item other than the last item to the end of the list by specifying a position greater than the last element will break the list. It sets the moved item's position to be one greater than the largest position and also shifts the other list elements down, so you end up with a gap.

Example to demonstrate:

%w(rubygems dm-core dm-is-list).each{|r| require r }

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

class Todo
  include DataMapper::Resource

  property :id, Serial

  is :list


@todo_1 = Todo.create
@todo_2 = Todo.create
@todo_3 = Todo.create

@todo_1.position = -1

# => "[#<Todo id=1 position=-1>, #<Todo id=2 position=2>, #<Todo id=3 position=3>]"

@todo_1.position = 100

"[#<Todo id=1 position=4>, #<Todo id=2 position=1>, #<Todo id=3 position=2>]"

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