AJAX Lazy Loading with Sitecore MVC

There was request to implement search with lazy loading for Sitecore MVC project. Unfortunately there is no such option in Sitecore out of the box. But I found great article how it could be done on Sitecore project with web forms. That idea works fine for web forms, but it does not work for MVC.

I modified processor proposed in article to work with MVC layouts.

var url = "http://myurl/myItem?UseAjax=true&PresentationId=BACBFEE1-C0BB-4D8E-BA1A-D9F50CCA5B7F";  
  
$.ajax({  
 type: 'GET',  
 url: url  
}).done(function (data) {  
 //Your code  
});  

We will also need a MVC layout for the ajax queries (in the following code the MY_AJAX_LAYOUT_ID is the id of this layout) and this layout will only contain one placeholder (MY_AJAX_PLACEHOLDER in the code)
Now here is the custom layout resolver (look at the comments into the code):

namespace MyNamespace
{
  using System;
  using System.Linq;
  using System.Web;
  using Sitecore.Diagnostics;
  using Sitecore.Mvc.Pipelines;
  using Sitecore.Mvc.Pipelines.Response.GetPageRendering;
  using Sitecore.Mvc.Pipelines.Response.GetRenderer;
  using Sitecore.Mvc.Presentation;
  using System.Web.Routing;

  public class GetAjaxLayoutRendering : GetPageRenderingProcessor

  {
    public override void Process(GetPageRenderingArgs args)

    {
      bool useAjax;
      //First of all let's check if we are in ajax mode or not if not don't continue  
      var result = bool.TryParse(HttpContext.Current.Request.Params["UseAjax"], out useAjax);
      if (!result || !useAjax)
      {
        return;
      }

      //The second parameter we need to pass is the PresentationId if not present the query if not valid -> don't continue  
      var presentationId = HttpContext.Current.Request.Params["PresentationId"];
      if (string.IsNullOrEmpty(presentationId))
      {
        return;
      }

      //If the current item is null return  
      if (Sitecore.Context.Item == null)
      {
        return;
      }

      //Let's resolve the rendering  
      try
      {
        //Get the list of rendering for the current item  
        var renderings = args.PageDefinition.Renderings;
        //If found  
        if (renderings != null && renderings.Any())
        {
          //Get the first rendering corresponding to the requested one  
          var rendering = renderings.First(r => r.RenderingItem.ID.ToString().Equals(presentationId));
          
          if (rendering != null)
          {
            args.PageDefinition.Renderings.Remove(rendering);
            //Put this rendering into ajax layout  
            rendering.Placeholder = "MY_AJAX_PLACEHOLDER";
            
            rendering.LayoutId = new Guid(JetstreamShops.Business.Constants.Ids.AjaxLayoutItemId);
            var layout = renderings.First(x => x.RenderingType == "Layout");
            if (layout != null)
            {
              args.PageDefinition.Renderings.Remove(layout);
              for ( int i=0; i< args.PageDefinition.Renderings.Count; i++)
              {
                args.PageDefinition.Renderings[i].Placeholder =
                  args.PageDefinition.Renderings[i].Placeholder.Split('/').Last();
                args.PageDefinition.Renderings[i].LayoutId =
                  new Guid(MY_AJAX_LAYOUT_ID);
              }
              layout.LayoutId = new Guid(MY_AJAX_LAYOUT_ID);
              var getRedererArgs = new GetRendererArgs(new Rendering());
              getRedererArgs.LayoutItem =
                Sitecore.Context.Database.GetItem(MY_AJAX_LAYOUT_ID);

              layout.Renderer = PipelineService.Get().RunPipeline<GetRendererArgs, Renderer>(PipelineNames.GetRenderer, getRedererArgs, a => a.Result);
              
              args.PageDefinition.Renderings.Add(layout);
              args.PageDefinition.Renderings.Add(rendering);
            }
          }
        }
      }
      catch (Exception exception)
      {
        Log.Warn("Cannot render this!", exception, this);
      }
    }
  }
}

Configuration will look in next way:

<mvc.getPageRendering>
        <processor patch:after="*[@type='Sitecore.Mvc.Pipelines.Response.GetPageRendering.GetLayoutRendering, Sitecore.Mvc']" type="MyNamespace.GetAjaxLayoutRendering, MyAssembly"/>
</mvc.getPageRendering>

Many thanks to Vangansewinkel Benjamin whose idea was modified.