NVelocityView.cs :  » Web-Frameworks » MvcContrib » MvcContrib » ViewEngines » C# / CSharp Open Source

using System;
using System.Collections;
using System.IO;
using System.Web.Mvc;
using NVelocity;

namespace MvcContrib.ViewEngines{
  public class NVelocityView : IViewDataContainer, IView
  {
    private ViewContext _viewContext;
    private readonly Template _masterTemplate;
    private readonly Template _viewTemplate;

    public NVelocityView(Template viewTemplate, Template masterTemplate)
    {
      _viewTemplate = viewTemplate;
      _masterTemplate = masterTemplate;
    }

    public Template ViewTemplate
    {
      get { return _viewTemplate; }
    }

    public Template MasterTemplate
    {
      get { return _masterTemplate; }
    }

    public ViewDataDictionary ViewData
    {
      get { return _viewContext.ViewData; }
      set { throw new NotSupportedException(); }
    }

    public TempDataDictionary TempData
    {
      get { return _viewContext.TempData; }
      set { throw new NotSupportedException(); }
    }

    public void Render(ViewContext viewContext, TextWriter writer)
    {
      _viewContext = viewContext;
      VelocityContext context = CreateContext();


      bool hasLayout = _masterTemplate != null;
      if(hasLayout)
      {
        //Native NVelocity support for master/child template using #parse. No need to buffer the child template to a Stringwriter
        //which bypasses the response output... and will therefore cause any void child helper extension method
        //calls to fail to render in the correct location. #parse($childContent) must appear in the master template
        //See google group discussion thread: 
        //http://groups.google.com/group/mvccontrib-discuss/browse_thread/thread/0fc84d69db708322?hl=en 

        context.Put("childContent", _viewTemplate.Name);
        _masterTemplate.Merge(context, writer);
      }
      else
      {
        _viewTemplate.Merge(context, writer);
      }
    }

    private VelocityContext CreateContext()
    {
      var entries = new Hashtable(StringComparer.InvariantCultureIgnoreCase);
      if(_viewContext.ViewData != null)
      {
        foreach(var pair in _viewContext.ViewData)
        {
          entries[pair.Key] = pair.Value;
        }
      }
      entries["viewdata"] = _viewContext.ViewData;
      if(_viewContext.TempData != null)
      {
        foreach(var pair in _viewContext.TempData)
        {
          entries[pair.Key] = pair.Value;
        }
      }
      entries["tempdata"] = _viewContext.TempData;

      entries["routedata"] = _viewContext.RouteData;
      entries["controller"] = _viewContext.Controller;
      entries["httpcontext"] = _viewContext.HttpContext;

      CreateAndAddHelpers(entries);

      return new VelocityContext(entries);
    }

    private void CreateAndAddHelpers(Hashtable entries)
    {
      entries["html"] = entries["htmlhelper"] = new HtmlExtensionDuck(_viewContext, this);
      entries["url"] = entries["urlhelper"] = new UrlHelper(_viewContext.RequestContext);
    }
  }
}