Form class sketch

different_approach_to_user_controller.rb

class UserController < ApplicationController
  
  def create
    @user = SomeUserForm.new(params[:user]) do |f|
      f.user = User.new
      f.email = Email.new
    end
    return unless post?

    if @user.save
      render "YAY"
    end
  end
  
  def lowly_user_update
    @user = SomeUserForm.new(params[:user]) do |f|
      f.user = current_user
      f.email = f.user.current_email
    end
    return unless put?

    if @user.save
      render "YAY"
    end
  end
  
  def admin_user_update
    @user = SomeUserForm.new(params[:user]) do |f|
      f.user = User.find(params[:id])
      f.email = f.user.current_email
    end
    return unless put?

    if @user.save
      render "YAY"
    end
  end

end

some_user_form.rb

class SomeUserForm < AbstractForm

  # creates attribute accessor user
  # delegates parent_object_id to user
  with_option :owner => :user do |o|
    o.field :parent_object_id
    ...
  end
  
  # attribute accessor user already exists so nothing happens
  # delegates first_name, first_name= to user
  with_option :owner => :user, :write => true do |o|
    o.field :first_name
    ...
  end
  
  # creates attribute accessor email
  # delegates :address, :address= to email
  with_option :owner => :email do |o|
    o.field :address, :write => true
  end
  
  # creates attr_reader / attr_writer for password, pass. confirmation and terms of service check box
  with_options :owner => :self, :write => true do |o|
    o.field :password
    o.field :password_confirmation
    o.field :terms_of_service
  end

  # performs validations on attribute accessors  
  validates :terms_of_service, :acceptance => true
  validate  :password_fields

  # appends this validation to the existing model validators on User#first_name
  validate  :first_name_must_begin_with_Z

  validate_owner :user # same thing as validate association in active record
  
  def initialize(params, *args, &block)
    # invokes block, assigns attribute hashes, raises strong parameter exception if ACL is wrong
    super(params, *args, &block)
    
    # set protected attributes on user and email
    parent_object_id = 42 # same thing as user.parent_object_id = 42
    user.calculate_password_thingies! password
    email.user_id = user.id
  end

  # also:
  #
  # attributes, attributes= works as expected
  #
  # valid? is valid iff the form attributes are valid, validator inheritance works
  # on attributes shared by the form and model (first_name in this example has
  # inherited validators from user model + validators from form class)
  #
  # save iterates over owners (user and email in this case) and saves them in a
  # transaction in an "all or nothing" way

end

user_controller.rb

class UserController < ApplicationController

  def new
    @user = SomeUserForm.new do |f|
      f.user = User.new
      f.email = Email.new
    end
  end
  
  def create
    @user = SomeUserForm.new(params) do |f|
      f.user = User.new
      f.email = Email.new
    end
    
    # @user.valid? will be false
    if @user.save
      render "YAY"
    end
  end
  
  def current_user_edit
    @user = SomeUserForm.new do |f|
      f.user = current_user
      f.email = f.user.current_email
    end
  end

  # + create
  
  def admin_user_edit
    @user = SomeUserForm.new do |f|
      f.user = User.find(params[:id])
      f.email = f.user.current_email
    end
  end

  # + create

end