associations_fetching_error.rb

require 'rubygems'
require 'datamapper'

DataMapper.setup(:default, "sqlite3::memory:")
DataObjects::Sqlite3.logger = DataObjects::Logger.new(STDOUT, 0)

class Master
  include DataMapper::Resource
  
  property :id, Serial
  property :name, String

  has n, :slaves, :model => 'Slave'
end

class Slave
  include DataMapper::Resource
  
  property :id, Serial
  property :discriminator, Discriminator
  belongs_to :master
  
  class Nested < self
    property :name, String
  end
end

DataMapper.auto_migrate!

sql = <<-SQL
  INSERT INTO "masters" ("name") VALUES ('car')
  INSERT INTO "slaves" ("discriminator", "name", "master_id") VALUES ('Slave::Nested', 'wheel 1', 1)
  INSERT INTO "slaves" ("discriminator", "name", "master_id") VALUES ('Slave::Nested', 'wheel 2', 1)
  INSERT INTO "slaves" ("discriminator", "name", "master_id") VALUES ('Slave::Nested', 'wheel 3', 1)
  INSERT INTO "slaves" ("discriminator", "name", "master_id") VALUES ('Slave::Nested', 'wheel 4', 1)
SQL

sql.each do |l|
  Master.repository.adapter.execute(l)
end

#-------------------------------------------------------------------

# ERROR
# /usr/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/query.rb:803:
# in `assert_valid_fields_without_operator': +options[:field]+ entry :name does not map to a property in Slave (ArgumentError)

Master.first.slaves.each do |s|
  p s.name
end

# THIS WORK FINE:

Master.first.slaves.to_a.each do |s|
  p s.name
end

lazy_load_issue.rb

require 'rubygems'
require 'datamapper'

DataMapper.setup(:default, "sqlite3::memory:")
DataObjects::Sqlite3.logger = DataObjects::Logger.new(STDOUT, 0)

class Master
  include DataMapper::Resource
  
  property :id, Serial
  property :name, String

  has n, :slaves, :model => 'Slave'
end

class Slave
  include DataMapper::Resource
  
  property :id, Serial
  property :discriminator, Discriminator
  belongs_to :master
  
  class Nested < self
    property :name, String
  end
end

DataMapper.auto_migrate!

sql = <<-SQL
  INSERT INTO "masters" ("name") VALUES ('car')
  INSERT INTO "slaves" ("discriminator", "name", "master_id") VALUES ('Slave::Nested', 'wheel 1', 1)
  INSERT INTO "slaves" ("discriminator", "name", "master_id") VALUES ('Slave::Nested', 'wheel 2', 1)
  INSERT INTO "slaves" ("discriminator", "name", "master_id") VALUES ('Slave::Nested', 'wheel 3', 1)
  INSERT INTO "slaves" ("discriminator", "name", "master_id") VALUES ('Slave::Nested', 'wheel 4', 1)
SQL

sql.each do |l|
  Master.repository.adapter.execute(l)
end

#-------------------------------------------------------------------

# Master.first.slaves.each do |s| <------ THIS DOESN'T WORK :/
Master.first.slaves.to_a.each do |s|
  p s.name
end

# causes:

#SELECT "id", "name" FROM "masters" ORDER BY "id" LIMIT 1
#SELECT "id", "discriminator", "master_id" FROM "slaves" WHERE ("master_id" = 1 AND "discriminator" IN ('Slave', 'Slave::Nested')) ORDER BY "id"
#SELECT "id", "discriminator", "name" FROM "slaves" WHERE "id" = 1 ORDER BY "id"
#SELECT "id", "discriminator", "name" FROM "slaves" WHERE "id" = 2 ORDER BY "id"
#SELECT "id", "discriminator", "name" FROM "slaves" WHERE "id" = 3 ORDER BY "id"
#SELECT "id", "discriminator", "name" FROM "slaves" WHERE "id" = 4 ORDER BY "id"