Only store in IM if all attributes are present

gistfile1.rb

gem 'rails', :git => 'git://github.com/rails/rails.git', :ref => 'c1f397f82c7b3f352500832a399b5dbdc500b9c8'# change as required
require 'active_record'
require 'logger'

# Show ActiveRecord log output
ActiveRecord::Base.logger = Logger.new(STDOUT)

# Print out what version we're running
puts "Active Record #{ActiveRecord::VERSION::STRING}"

# Connect to an in-memory sqlite3 database (more on this in a moment)
ActiveRecord::Base.establish_connection(
  :adapter  => 'sqlite3',
  :database => ':memory:'
)

# Create the minimal database schema necessary to reproduce the bug
ActiveRecord::Schema.define do
  create_table :users, :force => true do |t|
    t.string :name
  end
end

# Create the minimal set of models to reproduce the bug
class User < ActiveRecord::Base
end

# Small patch to Identity Map
module ActiveRecord::IdentityMap
  class << self
    def add(record)
      repository[record.class.symbolized_sti_name][record.id] = record if record.class.column_names == record.attributes.keys
    end
  end
end

# Create some test data
#
# If you're demonstrating an exception, then this is probably not necessary,
# but if your bug is to do with the wrong data being returned from the database,
# then you'll probably need some test data to show that.
User.create(:name => "Ryan")

# Demonstrate the bug fix
ActiveRecord::IdentityMap.use do
  User.select(:id).find(1)
  User.find(1).name
  User.select(:id).find(1)
end