Rails date handling

README.md

requirements

• Rails 3.2.1
• column stored as date
• date entered as text
• blank/null date allowed
• validated on input
• formatted for display
• using decorator/presenter (i.e. draper)

weirdness

• checking for blank in the date validator
• accessing _before_type_cast in the date validator
• _before_type_cast in the decorator

chronic.rb

#wrap this instead of monkey patching it

module Chronic
  class << self
    alias :old_parse :parse

    def parse(value)
      return value if value.nil? || value.is_a?(Time) || value.is_a?(Date)
      old_parse(value.gsub(/\.\d*$/, "")) #chronic can't handle trailing milliseconds
    end
  end
end

date_validator.rb

class DateValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    user_input = record.send("#{attribute}_before_type_cast")
    record.errors[attribute] << 'must be a valid date' unless user_input.blank? || Chronic.parse(user_input)
  end
end

edit.html.erb

<%= render "shared/validation_messages", :target => @person %>

<%= form_for @person do |f| %>
  <p>
    <%= f.text_field :birthdate %>
  </p>
  <p>
    <%= f.submit %>
  </p>
<% end %>

person.rb

class Person < ActiveRecord::Base
  validates :birthdate, :date => true
end

person_decorator.rb

class PersonDecorator < ApplicationDecorator
  decorates :person

  def birthdate
    format_date(model.birthdate)
  end

  def birthdate_before_type_cast
    format_date(model.birthdate_before_type_cast)
  end

  private

  def format_date(d)
    Chronic.parse(d).strftime("%m/%d/%Y") rescue d
  end
end