gistfile1.rb

# This is a test case for a DataMapper bug handling a relation from a table to itself.
# ruby 1.8.7 (2009-06-08 patchlevel 173) [universal-darwin10.0]
# sqlite 3.6.22
# Mac OS X 10.6.3
require 'rubygems'
require 'dm-core' #0.9.12

DataMapper::Logger.new($stdout, :debug)
DataMapper.setup(:default, 'sqlite3::memory:')

class Relation
  include DataMapper::Resource
  property :id, Serial
  belongs_to :contacter, 'User'
  belongs_to :contact, 'User'
end

class User
  include DataMapper::Resource
  property :id, Serial
  property :url, String, :required => true, :unique => true
  has n, :relations, :child_key => [:contacter_id]
  has n, :contacts, :through => :relations, :model => 'User'

  def contactWithURL (url)
    return self.contacts.first(:url => url)
  end
end

DataMapper.auto_migrate!

user = User.create({:url => 'http://example.com'})
user.contactWithURL('http://rubylang.org')

# Result:
#
#~ ambiguous column name: users.id (code: 1, sql state: , query: SELECT "users"."id", "users"."local_name",
# "users"."url" FROM "users" INNER JOIN "relations" ON "users"."id" = "relations"."contact_id" INNER JOIN
# "users" ON "relations"."contacter_id" = "users"."id" WHERE ("users"."url" = 'http://rubylang.org' AND
# "relations"."contacter_id" = 1) GROUP BY "users"."id", "users"."local_name", "users"."url" ORDER BY
# "users"."id" LIMIT 1, uri: sqlite3://:memory:)
#
# DataObjects::SyntaxError: ambiguous column name: users.id
# 
# method execute_reader	in data_objects_adapter.rb at line 140
# method read	in data_objects_adapter.rb at line 140
# method with_connection	in data_objects_adapter.rb at line 269
# method read	in data_objects_adapter.rb at line 136
# method read	in repository.rb at line 145
# method lazy_load	in collection.rb at line 1111
# method lazy_load	in one_to_many.rb at line 270
# method to_a	in lazy_array.rb at line 275
# method first	in collection.rb at line 275
# method contactWithURL	in _datamapper_bug.rb at line 32
# at top level