1. The first step to this project could be a number of things! Let's get started by adding a reference to the NVelocity library (NVelocity.dll) in the dependencies folder.

2. Next we need to set up a quick database to use in the steps ahead. Do this by right-clicking on the App_Data folder in your project and select Add a new item. Choose a SQL Server database. I named my database Templates.

3. Now in your Server Explorer window you should see under the Data Connections section a Templates.mdf entry. Expand that entry. Right-click on the tables folder and add a new table.

4. Then we will add LINQ to SQL to our project. Do this by right-clicking on the Models folder and select Add new item. Select the LINQ to SQL Classes entry and name it Template.dbml.

5. When the design surface opens, drag your Template table from the server explorer onto the design surface. Save that file and close it. Then build your project (this builds the TemplateDataContext class for you, which we will need in the following steps).

6. Right-click on the Templates.mdf entry in the server explorer and select Properties. In the Properties window, select and copy the entire connection string entry. It should look something like this:

Data Source=.\SQLEXPRESS;AttachDbFilename={driveLetter}:\{pathToFile}\Templates.mdf;Integrated Security=True;User Instance=True

7. Now create a new class in the Models directory called TemplateRepository.cs. In this class, we will create a method called GetTemplateByViewName, which will be responsible for getting a template from the database by the template's name.

Models/TemplateRepository.cs:

public class TemplateRepository
{
public string GetTemplateByViewName(string ViewName)
{
string connectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename= {FilePathToDataBase}\Templates.mdf;Integrated Security= True;User Instance=True";
string result = "";
using(TemplateDataContext dc = new TemplateDataContext(connectionString))
{
Template template = (from t in dc.Templates where t.ViewName == ViewName select t).FirstOrDefault();
result = template != null ? template.TemplateContent : "The requested template was not found for view " + ViewName;
}
return result;
}
}

8. Now we can create a class that will work with NVelocity to parse our template. Right-click on the Models folder and add a new class called TemplateService.cs. This class will have a method called ParseTemplateByViewName. This method will be responsible for interacting with the NVelocity view engine to parse a passed in template.

Models/TemplateService.cs:

public class TemplateService
{
public string ParseTemplateByViewName(string template, Dictionary<string,object> viewParams)
{
VelocityContext vc = new VelocityContext();
foreach (var v in viewParams)
{
vc.Put(v.Key, v.Value);
}
//create the engine
VelocityEngine ve = new VelocityEngine();
ve.Init();
//the output stream
StringBuilder sb = new StringBuilder();
StringWriter sw = new StringWriter(sb);
//merge the template
ve.Evaluate(vc, sw, string.Empty, template);
return sb.ToString();
}
}

9. Now we need to add some code to our HomeController. Let's start by creating a new action called AnotherProduct(). Inside this action, we will still utilize the creation of a Product and a Category. And we will use our ViewModel as our transport object, which will carry the Product and Category instance for us. Then we need to create a dictionary that will take the variables we used in the parsing of our template. Lastly, we will call our TemplateService to parse out the template that the TemplateRepository locates for us.

Controllers/HomeController.cs:

public ActionResult AnotherProduct()
{
Product p = Builder<Product>
.CreateNew()
.Build();
Category c = Builder<Category>
.CreateNew()
.Build();
ProductView pv = new ProductView();
pv.CurrentCategory = c;
pv.CurrentProduct = p;
//define the variable context
Dictionary<string, object> variableParams = new Dictionary<string,object>();
variableParams.Add("ProductView", pv);
ViewData["content"] = new TemplateService()
.ParseTemplateByViewName(new TemplateRepository().GetTemplateByViewName("AnotherProduct"), variableParams);
return View();
}

10. Then you can create the AnotherView view. This will be an empty view that simply renders the content from within ViewData.

Views/Home/AnotherProduct.aspx:

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>
<%= ViewData["content"] %>

11. Lastly, before anything will actually come together, we need to add an entry into our database. The TemplateContent entry will look like this:

<html><head><title>$ProductView.CurrentProduct.ProductName</title></head><body><h2>$ProductView.CurrentProduct.ProductName</h2>Hello world from an NVelocity template!</body></html>

The ViewName will be AnotherProduct to match our AnotherProduct action.

12. Now you can start debugging by hitting F5 and see the results of our database-driven view.