Rails で Form クラス的なやつ

application_form.rb

class ApplicationForm
  include ActiveModel::Model

  def submit(params = {})
    params.each do |key, value|
      self.public_send("#{key}=", value)
    end

    self
  end

  def save
    raise NotImplementedError
  end
end

nyan_wan_form.rb

class NyanWanForm < ApplicationForm
  ## Attributes
  attr_reader :nyan

  # Define some attributes

  ## Validations

  # Define some validations

  def initialize(nyan)
    @nyan = nyan
  end

  def save
    return false unless valid?

    nyan.transaction do
      # do something
    end

    true
  end
end

nyans_controller.rb

class NyansController < ApplicationController
  def wans_new
    @form = NyanWanForm.new(@nyan)
  end

  def wans_create
    @form = NyanWanForm.new(@nyan).submit(nyan_wan_params)
    if @form.save
      # do something
    else
      render :wans_new
    end
  end

  private

  def nyan_wan_params
    params.require(:nyan_wan_form).permit(
      # Some attributes
    )
  end
end