C# How to dynamically load email template file dynamically

Question

i have a send mail routine which send mail and mail body taken from html file. when i call that routine then i send html file path with name. routine load html from that file and prepare body text.

now i want to develop a routine where mail html body will be injected dynamically to send mail routine. anyone please discuss how can i do it very nicely using interface. thanks

Answer 1

Use Json

[
  {
    "Name": "Template1",
    "Subject": "Monthly news letter",
    "Body": "<style>.fg-white {color: crimson;}</style><p>Hello ##NAME##</p><p class=\"fg-white\">##BODY##</p>"
  },
  {
    "Name": "Template2",
    "Subject": "Notice of intention",
    "Body": "<p>Hello ##NAME##</p><p class=\"fg-white\">##BODY##</p>"
  }
]

Class

public class EmailTemplate
{
    public string Name { get; set; }
    public string Subject { get; set; }
    public string Body { get; set; }
}

Mockup

public class MockupEmail
{
    public static string FileName => Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Templates.json");

    public static List<EmailTemplate> Read()
    {
        return  JsonConvert.DeserializeObject<List<EmailTemplate>>(File.ReadAllText(FileName));
    }
    public static void Write()
    {
        List<EmailTemplate> list = new List<EmailTemplate>
        {
            new EmailTemplate()
            {
                Name = "Template1", 
                Subject = "Monthly news letter", 
                Body = "<style>.fg-white {color: crimson;}</style><p>Hello ##NAME##</p><p class=\"fg-white\">##BODY##</p>"
            },
            new EmailTemplate()
            {
                Name = "Template2",
                Subject = "Notice of intention",
                Body = "<p>Hello ##NAME##</p><p class=\"fg-white\">##BODY##</p>"
            }
        };

        File.WriteAllText(FileName, JsonConvert.SerializeObject(list, Formatting.Indented));
    }
}

Quick example

MockupEmail.Write();

var templates = MockupEmail.Read();

var Template2 = templates.FirstOrDefault(x => x.Name == "Template1");

List<string> names = new List<string>() { "Mary","Bob","Jim" };

foreach (var name in names)
{
    var body = Template2
        .Body
        .Replace("##NAME##", name)
        .Replace("##BODY##", $"Great news {name}");

    Console.WriteLine(body);
    Console.WriteLine();
}

• Create the HTML in an editor or Visual Studio, flatten to a one liner and escape any characters as needed.
• Polish up the replace aspect if needed.

Viewed from Visual Studio output window

<style>.fg-white {color: crimson;}</style><p>Hello Mary</p><p class="fg-white">Great news Mary</p>

<style>.fg-white {color: crimson;}</style><p>Hello Bob</p><p class="fg-white">Great news Bob</p>

<style>.fg-white {color: crimson;}</style><p>Hello Jim</p><p class="fg-white">Great news Jim</p>

Answer 2

I like the answer by Karen. In the past (way past), I have used xslt transformations with xml data to build email templates.