base_form.rb

require 'ostruct'

class BaseForm
  include ActiveModel::Model
  attr_reader :attributes,
              :attributes_hash,
              :current_user,
              :params,
              :params_hash,
              :model

  delegate :id,
           :model_name,
           :new_record?,
           :persisted?,
           to: :model

  def initialize(current_user, params, attributes = {})
    @current_user    = current_user
    @params_hash     = params
    @params          = OpenStruct.new(params)
    @attributes_hash = attributes.to_h.symbolize_keys
    @attributes      = OpenStruct.new(attributes)
    @model           = setup_model

    prepopulate
  end

  def call
    raise NotImplementedError
  end

  def url
    self
  end

  def valid?
    super && model.valid?
  end

  private

  def setup_model
    raise NotImplementedError
  end

  def prepopulate
  end
end