dm-fail.rb

require "rubygems"
require "dm-core"
require "dm-timestamps"
require "pp"

class Entry
  include DataMapper::Resource
  
  has n, :related, :through => Resource, :model => Entry
  
  property :id,             Serial
  property :title,          String, :length => 255
  property :class_name,     Discriminator
  property :created_at,     DateTime
  property :updated_at,     DateTime
  property :published_at,   DateTime
  
end

class Person < Entry
	
	property :name,           String, :length => 255
	property :email,          String, :length => 255
	
end

class Work < Entry 
  
  property :body,           Text
  
end


DataMapper::Logger.new(STDOUT,:debug)
DataMapper.setup(:default, "sqlite3::memory:")
DataMapper.auto_migrate!

a = Work.create( :title => "ABC" , :body => "Bla bla..." )
b = Work.create( :title => "DEF" , :body => "Bla bla..." )
a.related << b
a.save

p a.related

log

 ~ (0.000038) SELECT sqlite_version(*)
 ~ (0.000059) DROP TABLE IF EXISTS "entries"
 ~ (0.000009) DROP TABLE IF EXISTS "entries"
 ~ (0.000009) DROP TABLE IF EXISTS "entries"
 ~ (0.000010) DROP TABLE IF EXISTS "entry_entries"
 ~ (0.000011) PRAGMA table_info("entries")
 ~ (0.000299) CREATE TABLE "entries" ("id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, "title" VARCHAR(255), "class_name" VARCHAR NOT NULL, "created_at" TIMESTAMP, "updated_at" TIMESTAMP, "published_at" TIMESTAMP, "name" VARCHAR(255), "email" VARCHAR(255), "body" TEXT)
 ~ (0.000011) PRAGMA table_info("entries")
 ~ (0.000009) PRAGMA table_info("entries")
 ~ (0.000006) PRAGMA table_info("entry_entries")
 ~ (0.000131) CREATE TABLE "entry_entries" ("entry_id" INTEGER NOT NULL, "related_id" INTEGER NOT NULL, PRIMARY KEY("entry_id", "related_id"))
 ~ (0.000043) INSERT INTO "entries" ("title", "class_name", "created_at", "updated_at", "body") VALUES ('ABC', 'Work', '2010-01-27T13:17:00+01:00', '2010-01-27T13:17:00+01:00', 'Bla bla...')
 ~ (0.000161) INSERT INTO "entries" ("title", "class_name", "created_at", "updated_at", "body") VALUES ('DEF', 'Work', '2010-01-27T13:17:00+01:00', '2010-01-27T13:17:00+01:00', 'Bla bla...')
 ~ (0.000053) SELECT "entry_id", "related_id" FROM "entry_entries" WHERE ("entry_id" = 1 AND "related_id" = 2) ORDER BY "entry_id", "related_id" LIMIT 1
 ~ (0.000062) INSERT INTO "entry_entries" ("entry_id", "related_id") VALUES (1, 2)
 ~ (0.000068) SELECT "entries"."id", "entries"."class_name", "entries"."title", "entries"."created_at", "entries"."updated_at", "entries"."published_at" FROM "entries" INNER JOIN "entry_entries" ON "entries"."id" = "entry_entries"."related_id" INNER JOIN "entries" ON "entry_entries"."entry_id" = "entries"."id" WHERE ("entry_entries"."entry_id" = 1 AND "entries"."class_name" IN ('Entry', 'Person', 'Work')) GROUP BY "entries"."id", "entries"."class_name", "entries"."title", "entries"."created_at", "entries"."updated_at", "entries"."published_at" ORDER BY "entries"."id"
 ~ ambiguous column name: entries.id (code: 1, sql state: , query: SELECT "entries"."id", "entries"."class_name", "entries"."title", "entries"."created_at", "entries"."updated_at", "entries"."published_at" FROM "entries" INNER JOIN "entry_entries" ON "entries"."id" = "entry_entries"."related_id" INNER JOIN "entries" ON "entry_entries"."entry_id" = "entries"."id" WHERE ("entry_entries"."entry_id" = 1 AND "entries"."class_name" IN ('Entry', 'Person', 'Work')) GROUP BY "entries"."id", "entries"."class_name", "entries"."title", "entries"."created_at", "entries"."updated_at", "entries"."published_at" ORDER BY "entries"."id", uri: sqlite3://:memory:)
DataObjects::SyntaxError: ambiguous column name: entries.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 each	in lazy_array.rb at line 409
method each	in collection.rb at line 506
method map	in collection.rb at line 970
method inspect	in collection.rb at line 970
method p	in dm-fail.rb at line 43
at top level	in dm-fail.rb at line 43

Program exited with code #1 after 3.97 seconds.

tested queries

# FAIL

#SELECT "entries"."id", "entries"."class_name", "entries"."title", "entries"."created_at", "entries"."updated_at", "entries"."published_at" 
#FROM "entries" 
#INNER JOIN "entry_entries" 
#ON "entries"."id" = "entry_entries"."related_id" 
#INNER JOIN "entries" 
#ON "entry_entries"."entry_id" = "entries"."id" 
#WHERE ("entries"."class_name" IN ('Entry', 'Person', 'Work') 
#AND "entry_entries"."entry_id" = 1) 
#GROUP BY "entries"."id", "entries"."class_name", "entries"."title", "entries"."created_at", "entries"."updated_at", "entries"."published_at" ORDER BY "entries"."id"


# WIN

#SELECT "entries"."id", "entries"."class_name", "entries"."title", "entries"."created_at", "entries"."updated_at", "entries"."published_at" 
#FROM "entries" 
#INNER JOIN "entry_entries" 
#ON "entries"."id" = "entry_entries"."related_id" 
#WHERE ("entries"."class_name" IN ('Entry', 'Person', 'Work') 
#AND "entry_entries"."entry_id" = 1) 
#GROUP BY "entries"."id", "entries"."class_name", "entries"."title", "entries"."created_at", "entries"."updated_at", "entries"."published_at" ORDER BY "entries"."id"