Validate hash via ActiveModel::Validations

validation.rb

require 'bundler/setup'
require 'active_model'

class ParamValidation
  include ActiveModel::Validations

  validates :page, :format => /\d+/

  attr_accessor :page

  def initialize(params)
    self.page = params[:page]
  end
end

params = {:page => 'abc'}

v = ParamValidation.new(params)
puts v.valid?.inspect
puts v.errors.full_messages.inspect

params = {:page => 123}

v = ParamValidation.new(params)
puts v.valid?.inspect
puts v.errors.full_messages.inspect