ASP.NET MVC Email

Question

Is their a solution to generate an email template using an ASP.NET MVC View without having to jump through hoops.

Let me elaborate jumping through hoops.

var fakeContext = new HttpContext(HttpContext.Current.Request, fakeResponse);
var oldContext = HttpContext.Current;
HttpContext.Current = fakeContext;
var html = new HtmlHelper(new ViewContext(fakeControllerContext,
  new FakeView(), viewDataDictionary, new TempDataDictionary()),
  new ViewPage());
html.RenderPartial(viewName, viewData, viewDataDictionary);
HttpContext.Current = oldContext;

The above code is using the current HttpContext to fake a new Context and render the page with RenderPartial, we shouldn't have to do this.

Another very detailed solution using ControllerContext and .Render: (IEmailTemplateService, Headers/Postback WorkAround) but pretty much doing the same thing with a lot more code.

I on the other hand, am looking for something that would just render a View without having to POST/GET and generates me a simple string that I can send off through my Email code. Something that doesn't run into errors such as posting headers twice or faking some piece of data.

EX:

//code which does not fire Render, RenderPartial... etc
var email = emailFramework.Create(viewData, view); 

---

See my solution bellow or follow this link:

My Solution using spark: (12/30/2009) ASP.NET MVC Email Template Solution

Nonbeliever

That's how MS engine works and we can't change it; so why bother? Doesn't the solution work? If it works, just use it. There're many things we have to work around; for example I recently needed to pass lambdas to custom attributes; but I can't; so I just pass strings and live with it. This world is not perfect. – Uninterrupted

I know that ASP.NET MVC is growing from its older brother ASP.NET and because of it there are down sides. However, sometimes as a developer it is important to bring up issues, even if they are meaningless to some... Maybe, the framework is meant to work this way, maybe it's not. I don't know this I didn't write it, I am just asking if it can work the way I think it should. I am sorry, I am just curious. edit: I am also very interested in other solutions :) – Nonbeliever

Answer 1

This is what I wanted the ASP.NET MVC ViewEngine to do, but it's in Spark, just follow the latest link right bellow,

Update (12/30/2009) Cleaner Version: ASP.NET MVC Email Template Solution

---

(11/16/2009) Or, Louis DeJardin Console Application Version:

using System;
using Spark;
using Spark.FileSystem;

public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public abstract class EmailView : AbstractSparkView
{
    public User user { get; set; }
}

class Program
{
    static void Main(string[] args)
    {
        // following are one-time steps

        // create engine
        var settings = new SparkSettings()
            .SetPageBaseType(typeof(EmailView));

        var templates = new InMemoryViewFolder();
        var engine = new SparkViewEngine(settings)
                     {
                         ViewFolder = templates
                     };

        // add templates
        templates.Add("sample.spark", @"Dear ${user.Name}, This is an email.Sincerely, Spark View Engine http://constanto.org/unsubscribe/${user.Id}");

        // following are per-render steps

        // render template
        var descriptor = new SparkViewDescriptor()
            .AddTemplate("sample.spark");

        var view = (EmailView)engine.CreateInstance(descriptor);
        view.user = new User { Id = 655321, Name = "Alex" };
        view.RenderView(Console.Out);
        Console.ReadLine();
    }
}

I decided to use this method because it seems to be the one that does everything right, it:

• Does not use any HttpContext/ControllerContext or mess with routing data!
• It can implement Header/Footer to allow templates!
• You can use loops, conditionals, etc...
• It's clean, light weight especially if you plan to move entirely to spark view engine!

Please, make sure to read these posts. All credit to Louis DeJardin see his tutorials :): Using Spark as a general purpose template engine!, Email Templates Revisited

Nonbeliever

this works very well if you're already using spark as your view engine as we are. Thanks! – Reggi

Answer 2

Why do you need to create the email from a view? Why not use a plain old template file? I do this all the time - I make a template and use the NVelocity engine from the castle project (not to be confused with an nvelocity VIEW engine) to render the template.

Example:

var nvEngine = new NVelocityEngine();
nvEngine.Context.Add("FullName", fullName);
nvEngine.Context.Add("MallName", voucher.Mall.Name);
nvEngine.Context.Add("ConfirmationCode", voucher.ConfirmationCode);
nvEngine.Context.Add("BasePath", basePath);
nvEngine.Context.Add("TermsLink", termsLink);
nvEngine.Context.Add("LogoFilename", voucher.Mall.LogoFilename);

var htmlTemplate = System.IO.File.ReadAllText(
    Request.MapPath("~/App_Data/Templates/Voucher.html"));

var email = nvEngine.Render(htmlTemplate);

The NVelocityEngine class is a wrapper I wrote around the NVelocity port provided by the Castle project as shown below:

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using NVelocity;
using NVelocity.App;

namespace MyProgram
{
    /// <summary>
    /// A wrapper for the NVelocity template processor
    /// </summary>
    public class NVelocityEngine : VelocityEngine
    {
        Hashtable context = new Hashtable();

        /// <summary>
        /// A list of values to be merged with the template
        /// </summary>
        public Hashtable Context
        {
            get { return context; }
        }

        /// <summary>
        /// Default constructor
        /// </summary>
        public NVelocityEngine()
        {
            base.Init();
        }

        /// <summary>
        /// Renders a template by merging it with the context items
        /// </summary>
        public string Render(string template)
        {
            VelocityContext nvContext;

            nvContext = new VelocityContext(context);
            using (StringWriter writer = new StringWriter())
            {
                this.Evaluate(nvContext, writer, "template", template);
                return writer.ToString();
            }
        }
    }
}

In this way, you don't have to meddle with the view engine at all, and you can theoretically chain this with the ASP.NET view engine if you wanted, like I have done in the following controller method:

public ActionResult ViewVoucher(string e)
{
    e = e.Replace(' ', '+');
    var decryptedEmail = CryptoHelper.Decrypt(e);
    var voucher = Voucher.FindByEmail(decryptedEmail);
    if (voucher == null) return View("Error", new Exception("Voucher not found."));

    var basePath = new Uri(Request.Url, Url.Content("~/")).ToString();
    var termsLink = new Uri(Request.Url, Url.Action("TermsGC", "Legal")).ToString();
    basePath = basePath.Substring(0, basePath.Length - 1);

    var fullName = voucher.FirstName;
    if (!string.IsNullOrEmpty(voucher.LastName))
        fullName += " " + voucher.LastName;

    var nvEngine = new NVelocityEngine();
    nvEngine.Context.Add("FullName", fullName);
    nvEngine.Context.Add("MallName", voucher.Mall.Name);
    nvEngine.Context.Add("ConfirmationCode", voucher.ConfirmationCode);
    nvEngine.Context.Add("BasePath", basePath);
    nvEngine.Context.Add("TermsLink", termsLink);
    nvEngine.Context.Add("LogoFilename", voucher.Mall.LogoFilename);

    var htmlTemplate = System.IO.File.ReadAllText(
        Request.MapPath("~/App_Data/Templates/Voucher.html"));

    return Content(nvEngine.Render(htmlTemplate));
}

Companion

Thank you this is intresting, will look more into this now. Sample: castleproject.org/others/nvelocity/usingit.html#step3 Loops: castleproject.org/others/nvelocity/improvements.html#fancyloops – Nonbeliever

Hi Chris, so after a simple implementation of this how would you do subTemplates, or masterTemplates? I tried #path("master.vm") but it wouldn't work... – Nonbeliever

The initial design doesn't support nested templates, but I suppose you could modify the Render method of the NVelocity class to recursively render the templates in whatever way suited your need. Alternatively, you could download the Castle source code and modify the core velocity engine code, but that seems a bit much and it ought to be easier to extend it through the wrapper class. – Companion

Awesome! I would just suggest hiding Context and providing an AddContext method instead. Information hiding, Law of Demeter and all that. – Mayfield

Answer 3

Try using spark view engine (http://www.sparkviewengine.com/). It is easy to use, nicer than standard engine and doesn't require to fake context.

You can also use function from this answer Render a view as a string , but it requires faking context. This is the way standard view engine works and you can do nothing about that.

This is my extension class that is used to generate views to string. First is for standard view engine, second for Spark:

public static class ControllerHelper
{
    /// <summary>Renders a view to string.</summary>
    public static string RenderViewToString(this Controller controller,
                                            string viewName, object viewData)
    {
        //Getting current response
        var response = HttpContext.Current.Response;
        //Flushing
        response.Flush();

        //Finding rendered view
        var view = ViewEngines.Engines.FindPartialView(controller.ControllerContext, viewName).View;
        //Creating view context
        var viewContext = new ViewContext(controller.ControllerContext, view,
                                          controller.ViewData, controller.TempData);

        //Since RenderView goes straight to HttpContext.Current, we have to filter and cut out our view
        var oldFilter = response.Filter;
        Stream filter = new MemoryStream(); ;
        try
        {
            response.Filter = filter;
            viewContext.View.Render(viewContext, null);
            response.Flush();
            filter.Position = 0;
            var reader = new StreamReader(filter, response.ContentEncoding);
            return reader.ReadToEnd();
        }
        finally
        {
            filter.Dispose();
            response.Filter = oldFilter;
        } 
    }

    /// <summary>Renders a view to string.</summary>
    public static string RenderSparkToString(this Controller controller,
                                            string viewName, object viewData)
    {
        var view = ViewEngines.Engines.FindPartialView(controller.ControllerContext, viewName).View;
        //Creating view context
        var viewContext = new ViewContext(controller.ControllerContext, view,
                                          controller.ViewData, controller.TempData);

        var sb = new StringBuilder();
        var writer = new StringWriter(sb);

        viewContext.View.Render(viewContext, writer);
        writer.Flush();
        return sb.ToString();
    }
}

Timekeeper

Hi LukLed, I am familiar with the Spark View Engine and have considered this solution previously, you might be right in that this would ultimately be the best way to go. Eventually I might be forced down this path. However, I feel that adding a second view engine into my project is just adding code onto what "should" be a simple solution and in reality not really fixing the original problem but working around it. The other two, methods you referenced are what I am trying to avoid. +1 but there just hast to be a better solution :( – Nonbeliever

There's a solution to this - use a workaround around web forms engine - a single view engine - Spark ;-) – Uninterrupted

The view engines job is to take in the view data and the view/template whatever. Generate a string(html/xml/etc) representation of it and send it off back to the browser via POST. However, those are two separate pieces. The rendering should have nothing to do with how the data gets transported... – Nonbeliever

In case of Spark view engine you can render directly to your stream. In case of standard engine, there is no other solution. Look at Reflector and you'll find that standard implementation was designed to output content directly to HttpContext.Current.Response. Although Render method of IView has 2 parameters (ViewContext viewContext, TextWriter writer), second one is just ignored and instead HttpContext.Current.Response is used. – Timekeeper

Answer 4

If you want simple text replacements, .NET has something for that:

        ListDictionary replacements = new ListDictionary();

        // Replace hard coded values with objects values
        replacements.Add("{USERNAME}", "NewUser");            
        replacements.Add("{SITE_URL}", "http://yourwebsite.com");
        replacements.Add("{SITE_NAME}", "My site's name");

        string FromEmail= "[email protected]";
        string ToEmail = "[email protected]";

        //Create MailDefinition
        MailDefinition md = new MailDefinition();

        //specify the location of template
        md.BodyFileName = "~/Templates/Email/Welcome.txt";
        md.IsBodyHtml = true;
        md.From = FromEmail;
        md.Subject = "Welcome to youwebsite.com ";

        System.Web.UI.Control ctrl = new System.Web.UI.Control { ID = "IDontKnowWhyThisIsRequiredButItWorks" };

        MailMessage message = md.CreateMailMessage(ToEmail , replacements, ctrl);

        //Send the message
        SmtpClient client = new SmtpClient();

        client.Send(message);

And the Welcome.txt file

    Welcome - {SITE_NAME}<br />
    <br />
    Thank you for registering at {SITE_NAME}<br />
    <br />
    Your account is activated and ready to go! <br />
    To login, visit <a href="{SITE_URL}">{SITE_NAME}</a> and use the following credentials:
    <br />
    username: <b>{USERNAME}</b><br />
    password: use the password you registered with
    <br />
    <br />

    - {SITE_NAME} Team

Again, this is only good for simple string replacements. If you plan emailing more data, you would need to format it properly then replace it.

Laundrywoman

Have you tried using this in an ASP.NET MVC application? This code throws an exception – Hypoderm

ASP.NET MVC is all I use it in. What exception is thrown? – Laundrywoman

I use the same method without issue as well. The really important bit is adding "new System.Web.UI.Control()" in the "owner" option of CreateMailMessage since you won't have anything else to put in there in MVC. – Advertence

Answer 5

You can consider using MvcMailer NuGet - it does just what you are looking for and does it cleanly. See the NuGet package here and the project documentation

Hope it helps!

Thetos

Answer 6

I created an overload to LukLed's RenderSparkToString method that allows you to use a spark layout along with your view:

public static string RenderSparkToString(this Controller controller,
                                        string viewName, string masterName, object viewData)
{
    var view = ViewEngines.Engines.FindView(controller.ControllerContext, viewName, masterName).View;
    //Creating view context
    var viewContext = new ViewContext(controller.ControllerContext, view,
                                      controller.ViewData, controller.TempData);

    var sb = new StringBuilder();
    var writer = new StringWriter(sb);

    viewContext.View.Render(viewContext, writer);
    writer.Flush();
    return sb.ToString();
}

I agree with Andrew though. I wish there was an easier way to do this with the web forms view engine.

Johannajohannah

Answer 7

Although this is a little old thread, I would encourage if you to take a look at the MvcMailer NuGet package - it simplifies the whole thing greatly and makes the mailer behave li

Thetos