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Changing template programmatically

This example describes how to programmatically change the template that is used to render a page.

Given that there is a page model registered like:

[ContentType]
    public class TypedPage : PageData
    {
      public virtual string Heading { get; set; }
      public virtual XhtmlString Content { get; set; }
    }

You can have several templates defined for the same typed page. The following example registers two templates for the same typed page.

  • One is StandardTemplate without tags which will be the default template to use when rendering page instances of type TypedPage.
  • The other template is another generic template for all pages that is more suitable for rendering for mobile devices.
[TemplateDescriptor]
    public partial class StandardTemplate : PageController<TypedPage>
    { }
    
    [TemplateDescriptor(Name = "MobileTemplate")]
    public partial class MobileTemplate : PageController<PageData>
    { }

To change the template that is used for a request, you can attach an event handler to an event that is raised when a template is chosen for a specific request. The following code sample attaches to the event and changes the template for request for TypedPage instances when the request comes from a mobile device.

[InitializableModule]
    public class MobileRedirectSample : IInitializableModule
    {
      private IHttpContextAccessor _httpContextAccessor;
      public void Initialize(InitializationEngine context)
      {
        _httpContextAccessor = context.Locate.Advanced.GetRequiredService<IHttpContextAccessor>();
        context.Locate.Advanced.GetRequiredService<ITemplateResolverEvents>().TemplateResolved
          += new EventHandler<TemplateResolverEventArgs>(MobileRedirectSample_TemplateResolved);
      }
    
      public void Uninitialize(InitializationEngine context)
      {
        context.Locate.Advanced.GetRequiredService<ITemplateResolverEvents>().TemplateResolved
          -= new EventHandler<TemplateResolverEventArgs>MobileRedirectSample_TemplateResolved);
      }
    
      void MobileRedirectSample_TemplateResolved(object sender, TemplateResolverEventArgs eventArgs)
      {
        if (eventArgs.ItemToRender != null && eventArgs.ItemToRender is TypedPage)
        {
          //The sample code uses package 'Wangkanai.Detection' for device detection
          var detection = _httpContextAccessor.HttpContext.RequestServices.GetRequiredService<IDetection>();
          if (detection.Device.Type == DeviceType.Mobile)
          {
            var mobileRender = eventArgs.SupportedTemplates
              .SingleOrDefault(r => r.Name.Contains("Mobile") &&
                r.TemplateTypeCategory == eventArgs.SelectedTemplate.TemplateTypeCategory);
    
            if (mobileRender != null)
            {
              eventArgs.SelectedTemplate = mobileRender;
            }
          }    
        }
      }
    
      public void Preload(string[] parameters)
      {
      }
    }

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