Sitecore.NVelocity

Apparently I was working with Sitecore and its mail template. Sitecore suggest using nVelocity for template rendering. I notices that they have their own version of nVelocity called Sitecore.NVelocity. The base code is essentially the same and the code for rendering the template is slightly different as follows ( as in original Velocity)

In the constructor

Velocity.Init();

For rendering call 

Velocity.Evaluate(context, generated, "nVelocityLog", reader);

nVelocity to render templates

nVelocity is a .Net-based template engine. It permits anyone to use the simple yet powerful template language to reference objects defined in .Net code. I use this template engine for rendering the mail templates in my application. This is a wonderful framework, with a defined syntax to render field values inside the template. For those who do not know, project is a port of the Jakarta Velocity to Microsoft .Net (written in C#). This is a discontinued project, but the Castle project fork  enhanced it to support their monorail implementation. There are different versions available, I used one from Castle project website which has a lot of bug fixes and features incorporated than the original.

Below is the sample code to illustrate nVelocity to render mail template.

using System;
using System.Collections.Generic;
using System.IO;
using Commons.Collections;
using NVelocity;
using NVelocity.App;
using System.Collections;

namespace NVelocitySample
{
  class Program
  {
    static VelocityEngine velocity;
    static void Main(string[] args)
    {
      InitializeVelocity();
 
      string output = GenerateOutput();
      Console.WriteLine(output);
    }

    private static void InitializeVelocity()
    {
      ExtendedProperties properties = new ExtendedProperties();

      velocity = new VelocityEngine(properties);
    }


    private static string GenerateOutput()
    {
        Message mail = new Message();


        mail.From = "sender@company.com";
        mail.To = "recipient@company.com";
        mail.Subject = "This a mail render example";
        mail.Body = "This is the body where replace a dictionary to show the versatility of nVelocity";
       

        Dictionary<string, string> coll = new Dictionary<string, string>();
        coll["key"] = "Hi,";



        string stringData = "From: $mail.From  \n";
        stringData += "To:   $mail.To \n\n";
        stringData += "Subject: $mail.Subject  \n\n";
        stringData += "$coll.get_Item('key') $mail.Body";


        Hashtable hashTable = new Hashtable();
        hashTable.Add("mail", mail);
        hashTable.Add("coll", coll);

        VelocityContext context = new VelocityContext(hashTable);

        StringWriter generated = new StringWriter();
        StringReader reader = new StringReader(stringData);
        velocity.Evaluate(context, generated, "nVelocityLog", reader);
        return generated.GetStringBuilder().ToString();


    }


   class Message
    {
        private string from;
        private string to;
        private string subject;
        private string body;

        public string From
        {
            get { return from; }
            set { from = value; }
        }

        public string To
        {
            get { return to; }
            set { to = value; }
        }

        public string Subject
        {
            get { return subject; }
            set { subject = value; }
        }

        public string Body
        {
            get { return body; }
            set { body = value; }
        }
    }

    class Coll
    {
        Dictionary<string, string> fields = new Dictionary<string, string>();

        public Dictionary<string, string> Fields
        {
            get { return fields; }
            set { fields = value; }
        }
    }
  }
}

Calling C# function in XSL

In my current project, someone was looking for calling a C# function in XSL transformation. The following example calls a C# function declared in an external assembly for XSL transformation. DollerEuroConverter class is defined in the assembly CurrencyConverter.dll. The GetEuroValue function is just a sample implementation to show how the data from xsl can be modified using C# function. I tested it using a XML Notepad, I got the following output.

CurrencyConverter class

using System;
namespace CurrencyConverter
{
    //our custom class
    public class DollerEuroConverter
    {
        //function that gets called from XSLT
        public string GetEuroValue(string xslDollar)
        {
            return (float.Parse(xslDollar) / 0.749962502).ToString("##.##");
        }

    }
}

CD.xml (Sample from w3schools)

<?xml version="1.0" encoding="ISO-8859-1"?>
<catalog>
  <cd>
    <title>Empire Burlesque</title>
    <artist>Bob Dylan</artist>
    <country>USA</country>
    <company>Columbia</company>
    <price>10.90</price>
    <year>1985</year>
  </cd>
  <cd>
    <title>Hide your heart</title>
    <artist>Bonnie Tyler</artist>
    <country>UK</country>
    <company>CBS Records</company>
    <price>9.90</price>
    <year>1988</year>
  </cd>
  <cd>
    <title>Greatest Hits</title>
    <artist>Dolly Parton</artist>
    <country>USA</country>
    <company>RCA</company>
    <price>9.90</price>
    <year>1982</year>
  </cd>
  <cd>
    <title>Still got the blues</title>
    <artist>Gary Moore</artist>
    <country>UK</country>
    <company>Virgin records</company>
    <price>10.20</price>
    <year>1990</year>
  </cd>
</catalog>

CD.xsl

<?xml version="1.0" encoding="utf-16"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                                xmlns:msxsl="urn:schemas-microsoft-com:xslt"
                xmlns:MyClass="CurrencyConverter.DollerEuroConverter">


  <msxsl:script language="C#" implements-prefix="MyClass">
    <msxsl:assembly href=".\bin\Debug\CurrencyConverter.dll" />
    <msxsl:using namespace="CurrencyConverter"/>

    <![CDATA[

        public string GetPrice(string data)

        {
          CurrencyConverter.DollerEuroConverter conveter = new CurrencyConverter.DollerEuroConverter();
          string days = conveter.GetEuroValue(data);
          return days;

        }

    ]]>

  </msxsl:script>
  
  <xsl:template match="/">
    <html>
      <body>
        <h2>My CD Collection</h2>
        <table border="1">
          <tr bgcolor="#9acd32">
            <th>Title</th>
            <th>Artist</th>
            <th>Price in Euro</th>
          </tr>
          <xsl:for-each select="catalog/cd">
            <tr>
              <td>
                <xsl:value-of select="title"/>
              </td>
              <td>
                <xsl:value-of select="artist"/>
              </td>
              <td>
                <xsl:value-of select="MyClass:GetPrice(price)"/>€
              </td>
            </tr>
          </xsl:for-each>
        </table>
      </body>
    </html>
  </xsl:template>
</xsl:stylesheet>