Uses Pikaday and Moment JS jQuery plugins to make a user-friendly DateTime picker to work with Rails

_form.html.erb

<%= stylesheet_link_tag "pikaday", :media => "all" %>

<%= form_for(@news) do |f| %>
<!-- Generate HTML -->
  <%= form_datetime_selector_helper(:obj => f, 
                                    :field_name => :publish_date, 
                                    :label_name => 'Publish Date', 
                                    :date => @news.publish_date).html_safe %>
<% end %>

<%= javascript_include_tag "moment.js" %>
<%= javascript_include_tag "pikaday.js" %>
<%= javascript_include_tag "pikaday.jquery.js" %>
<script>
    var startpicker = new Pikaday({ 
      field: $('#news_publish_date_date')[0],
      format: 'MMM D, YYYY'
    });

  $("#news_publish_date_date, #news_publish_date_hour, #news_publish_date_minute, #news_publish_date_ampm").change(function(){
    var d = $("#news_publish_date_date").val();
    var h = $("#news_publish_date_hour").val();
    var m = $("#news_publish_date_minute").val();
    var ampm = $("#news_publish_date_ampm").val();

    $("#news_publish_date").val(d + ' ' + h + ':' + m + ampm);   // populate the hidden field to submit back to server
  });

</script>

application_helper.rb

  def form_datetime_selector_helper(args = {})
    f = args[:obj]
    field_name = args[:field_name].to_sym
    full_fieldname = "#{f.object_name}_#{field_name}"
    date = args[:date]
    formatted_date = date.strftime("%b %-d, %Y") unless date.nil? # => MMM D, YYYY

    @hour_options = {"hour" => ""}
    (1..12).each do |hour|
      @hour_options = @hour_options.merge({ hour.to_s => hour })
    end

    @minute_options = {"minute" => ""}
    ['00', '15', '30', '45'].each do |minute|
      @minute_options = @minute_options.merge({ minute.to_s => minute })
    end
    
    @ampm_options = {"select" => ""}
    ['am', 'pm'].each do |ampm|
      @ampm_options = @ampm_options.merge({ ampm.to_s => ampm })
    end

    hour = date.try(:hour)
    if hour
      hour -=12 if hour > 12
    end

    minute = date.try(:minute)
    if minute
      minute = "00" if minute.to_i == 0
    end

    date_field = <<-FIELDS
    <div class='datetime'>
      <div>
        #{f.label field_name, args[:label_name], :class => 'datetime-label'}
        #{f.hidden_field field_name, :class => 'datetime-hidden'}
      </div>
      <div style="float:left">
        #{text_field_tag "#{full_fieldname}_date", formatted_date, :size => 10 }
      </div>
      <div style="float:left">
        #{select_tag "#{full_fieldname}_hour", options_for_select(@hour_options.to_a, hour) }
      </div>
      <div style="float:left">
        #{select_tag "#{full_fieldname}_minute", options_for_select(@minute_options, minute) }
      </div>
      <div style="float:left">
        #{select_tag "#{full_fieldname}_ampm", options_for_select(@ampm_options, date.try(:strftime, "%P")) }
      </div>
      <div style="clear:both"></div>
    </div>
    FIELDS


  end