Date/Time Reformer for Rails 4.1 and Virtus.

date_time_reformer.rb

class DateTimeReformer
  include ActiveModel::Validations

  def initialize(object: nil, field_name: nil, date: nil, time: nil)
    @object, @field_name, @date, @time = object, field_name, date, time
    @time.nil? ? check_valid_date(@date) : check_valid_date_time(@date, @time)
  end

  def reform_date
    return unless errors.empty?
    date = convert_values_to_integer(@time ? @date.merge(@time) : @date)
    reformed_value = Date.new(date[:year], date[:month], date[:day])
    reformed_value = DateTime.new(
      date[:year], date[:month], date[:day], date[:hour], date[:minute]
    ) unless @time.nil?
    @object.send("#{@field_name}=", reformed_value)
  end

  private

  def convert_values_to_integer(hash)
    hash.each { |_k, v| hash[hash.key v] = Integer(v, 10) if v }
  end

  def check_valid_date(d)
    Date.strptime("#{d[:year]}-#{d[:month]}-#{d[:day]}", '%Y-%m-%d')
  rescue ArgumentError => e
    process_exception(e)
  end

  def check_valid_date_time(d, t)
    DateTime.strptime(
      "#{d[:year]}-#{d[:month]}-#{d[:day]}T#{t[:hour]}:#{t[:minute]}:00",
      '%Y-%m-%dT%H:%M:%S')
  rescue ArgumentError => e
    process_exception(e)
  end

  def process_exception(e)
    if e.message =~ /invalid value for Integer()/ || e.message =~ /invalid date/
      errors.add @field_name.to_sym, 'is an invalid date.'
      nil
    else
      fail e
    end
  end
end

note.md

Using Virtus as a form object, I found myself needing to take the date and time params that Rails was passing and re-form them into a Date or DateTime object.

If invalid date is passed back, I wanted to have errors I could pass directly to the form object.