Using the Handlebars templates with SendGridForEpi

I'm pretty sure you've checked out the Handlebars.js syntax and know that it's a powerful way to insert data into a template. This is very welcome since for example looping stuff in a typical SendGrid template case such as an order confirmation was a bit of a hassle before, often having to construct a big chunk of HTML as the likely option.

• An Overview of How to Use SendGrid's Dynamic Templates for Your Transactional Emails at sendgrid.com

So... When using it from C# it's best to forget about the old substitution variable way and instead think view model. In this very simple example I need two string properties where one will get an HTML value set.

private class CommentTemplateData
{
    [JsonProperty("whoIs")]
    public string WhoIs { get; set; }

    [JsonProperty("commentText")]
    public string CommentText { get; set; }
}

I put some JsonProperty-decorations in there to not offend anyone working with JS with improper name casing.

To avoid getting the markup in commentText escaped I need to "triple-stash" that property in the SendGrid template.

Then to wrap it up when sending through SendGridForEpi I use the TemplateData property found on the regular SendGrid Personalization object.

var mail = new SendGridMessage
{
    From = new EmailAddress("noreply@krompaco.nu"),
    TemplateId = "the-id-found-in-the-sendgrid-template-editor",
    Personalizations = new List<Personalization>()
};

mail.Personalizations.Add(
    new Personalization()
    {
        Tos = new List<EmailAddress>
        {
          new EmailAddress("notifications@krompaco.nu")
        },
            TemplateData = new CommentTemplateData
        {
            WhoIs = "Some Name",
            CommentText =
              "<p>First line of comment.</p><p>Second line of comment.</p>",
        }
});

this.mailService.AddToQueue(new MailQueueItem
{
    Date = DateTime.UtcNow,
    Mail = mail
});

This support was added in the official C# library with 9.10 released 2018-09-12. The SendGridForEpi package dependent on this version as a minimum is 1.2.2 which will be up on Epi's NuGet feed shortly.

Check the package source code on Github or the initial blog post if you missed the SendGridForEpi introduction.