Technical
Calendar Tag

This helper uses javascript calendar from http://www.mattkruse.com/javascript/calendarpopup/

This helper is merely encapsulation that lets you have 4 lines of code that would incorporate text_field,link_to and actual popup calendar.

download CalendarPopUp.js to your public/javascripts directory

Layout ( Put following in the head declaration )

<%= javascript_include_tag "CalendarPopup.js" %>
    <SCRIPT LANGUAGE="JavaScript">
       var cal = new CalendarPopup();
    </SCRIPT>

Helper file

Either copy the following on the controller level app/helpers/controler_name_herlper.rb or in a global app/helpers/application_helper.rb

def calendar_js_tag(opt_for_txt={},opt_for_url={})
  calHelper = %()
  calHelper << %(<table><tr>)
  calHelper << %(<td>#{text_field opt_for_txt[:obj_name],opt_for_txt[:attr_name],
                                    :value => convert_date(opt_for_txt[:data]),:style => "width:100px"}</td>\n)

url_java_script_part = "cal.select(document.forms['#{opt_for_url[:form_name]}'].#{opt_for_txt[:obj_name]}_#{opt_for_txt[:attr_name]}," + "'#{opt_for_url[:anchor]}','#{opt_for_url[:format]}')" 

  calHelper << %(<td>#{link_to_function "select",
                                          url_java_script_part,
                                          {:name => opt_for_url[:anchor],:id => opt_for_url[:anchor]}}</td>)
    calHelper << %(</tr></table>)
end

def convert_date(date)
  return date.strftime("%m/%d/%Y") if !date.nil?
  return nil if date.nil?
end

In case You want image for the link

 def calendar_js_tag(opt_for_txt={},opt_for_url={})
    calHelper = %()
    calHelper << %(<table><tr>)
    calHelper << %(<td>#{text_field opt_for_txt[:obj_name],opt_for_txt[:attr_name],
                                    :value => convert_date(opt_for_txt[:data]),
                                    :style => "width:100px"}</td>\n)
    url_java_script_part = "cal.select(document.forms['#{opt_for_url[:form_name]}'].#{opt_for_txt[:obj_name]}_#{opt_for_txt[:attr_name]}," +
                           "'#{opt_for_url[:anchor]}','#{opt_for_url[:format]}')" 
    calHelper << %(<td>#{link_to_function image_tag("calendar",:border => "0"),
                                          url_java_script_part,
                                          {:name => opt_for_url[:anchor],:id => opt_for_url[:anchor]}}</td>)
    calHelper << %(</tr></table>)
  end

View

Note: name for this form will correspond to the calendar_helper Also: anchor should differ for each field, this will signify to javascript where to show the calendar.

<%= form_tag( {:action => "update_documentation_contract"},{:name => "isda_form"}) %>

 <%= calendar_js_tag(
              {:obj_name => 'isda_ma',:attr_name => 'linkLetterDate',:data => @isda_ma.linkLetterDate},
              {:form_name => 'isda_form',:anchor => "anchor2",:format => 'MM/dd/yyyy'}
          )%>
<%= end_form_tag %>

Contorller

 def documentation_contract
    @legal_entity = LegalEntity.find(session[:legal_entity_id])
    @isda_ma = find_or_new
    @selected_sub_tab = "documentation_contract" 
  end

As always everything is refactorable, and as usual I appreciate your input.