Sending Templated E-mail using the Spark View Engine

We have a couple of systems that send personalized e-mail notifications to our users, and for a while I’ve been looking for a nice way to use a proper MVC-style view engine to populate the templates for personalizing these e-mails. The problem is, most of the ASP.NET view engines are so tightly bound to System.Web and things like HttpContext.Current and the VirtualPathProvider that running them in a standalone console application is really quite unpleasant.

Well, with a bit of hacking around and some help from @RobertTheGrey, I’ve finally got the awesome Spark view engine running within a console app. No fake VirtualPathProviders, no mocking or spoofing HttpContext.Current – it just works.

The secret is this little snippet of code here:

var templateFolder = @"D:\Templates\";
var viewFolderParameters = new Dictionary<string, string> {
    {"basePath", templateFolder}
};
var settings = new SparkSettings();
settings.SetPageBaseType(typeof(TemplateBase));
settings.AddViewFolder(ViewFolderType.FileSystem, viewFolderParameters);
engine = new SparkViewEngine(settings);

which spins up a fresh SparkSettings configuration object, tells it to use your own TemplateBase class and the templates folder you’ve specified. The method that actually does the population looks like this:

public string Populate(string templateFileName, object data) { 
  var writer = new StringWriter(); 
  var descriptor = new SparkViewDescriptor(); 
  descriptor.AddTemplate(templateFileName); 
  var view = (TemplateBase)engine.CreateInstance(descriptor); 
  try { 
    view.ViewData = new ViewDataDictionary(data); 
    view.RenderView(writer); 
  } finally { 
    engine.ReleaseInstance(view); 
  } 
  return (writer.ToString()); 
}

so you end up with little snippets like this:

foreach(var user in userRepository.RetrieveUsersWhoShouldGetWelcomeEmails()) {
    var htmlBody = templater.Populate("welcome_html.spark”, user):
    var textBody = templater.Populate(“welcome_text.spark”, user):
    mailServer.SendMail(“me@mysite.com”, user.Email, “Welcome!”, textBody, htmlBody);
}

There’s a full working example in the Spark repository on GitHub if you’re interested.

Spark photo © SCholewiak via Flickr – used under Creative Commons attribution license.