dm_filters_raising.rb

require 'dm-core'
require 'dm-migrations'

class PetSpecies
  include DataMapper::Resource

  has n, :pets
  has n, :people, :through => :pets
  property :id, Serial

  def self.filter
    all.map{|k| ["species_ #{k.id}"]}
  end

end

class Pet
  include DataMapper::Resource

  belongs_to :pet_species
  belongs_to :person

  property :id, Serial


  def self.filter
    all.map{|k| ["pet_ #{k.id}"]}
  end

end

class Person
  include DataMapper::Resource

  has n, :pets
  has n, :pet_species, :through => :pets
  property :id, Serial

  def self.filter
    all.map{|k| ["person_ #{k.id}"]}
  end

end



DataMapper.setup(:default, 'sqlite:///tmp/testdb')
DataMapper.auto_migrate!!
DataMapper.finalize

s = PetSpecies.create
p = Person.create
3.times{
  Pet.create(:person => p, :pet_species => s)
}

p.pet_species # does not raise
p.pet_species.filter # raises
s.people # does not raise
s.people.filter # raises