Rendering Emails with Razor Views

Relevant source files

The following files were used as context for generating this wiki page:

• examples/RenderRazor/Controllers/EmailController.cs
• examples/RenderRazor/Program.cs
• examples/RenderRazor/README.md
• examples/README.md
• README.md

The Resend .NET SDK allows you to generate dynamic HTML email content using the Razor view engine. This approach replaces manual string concatenation with structured templates, improving code readability and maintainability.

By using Razor, you separate presentation logic from application logic. You define email layouts in .cshtml files and populate them with strongly-typed models before sending via the IResend client.

Sources: examples/README.md, examples/RenderRazor/README.md:1-5

System Architecture

The rendering system integrates standard ASP.NET Core MVC components with the Resend SDK. The application uses the IRazorViewEngine to locate and compile templates, which are then rendered into strings for the EmailMessage.HtmlBody property.

Core Components

Component	Description
IRazorViewEngine	Locates and retrieves the .cshtml view files.
IResend	The primary client interface for transmitting the rendered email.
ActionContext	Provides the necessary execution context for the Razor engine.
ViewContext	Encapsulates the model data and output writer for the rendering process.

Sources: examples/RenderRazor/Controllers/EmailController.cs:17-40, examples/RenderRazor/Program.cs:20-27

Data Flow

The following diagram illustrates the flow from a request to render an email through to the final transmission via the Resend API.

This process ensures that the Razor engine has all necessary services, such as TempData providers and metadata providers, to execute the view logic.

Sources: examples/RenderRazor/Controllers/EmailController.cs:88-140

Implementation Details

View Engine Configuration

To enable Razor rendering, you must register the required services in the application container. This includes adding controllers and Razor pages to the service collection.

var builder = WebApplication.CreateBuilder( args );
builder.Services.AddControllers();
builder.Services.AddRazorPages();

builder.Services.AddHttpClient<ResendClient>();
builder.Services.AddTransient<IResend, ResendClient>();

Sources: examples/RenderRazor/Program.cs:18-27

Rendering Logic

The RenderEmail<T> method handles the manual invocation of the Razor engine. It performs the following steps:

1. View Lookup: Uses _razor.GetView with a specific path (e.g., ~/Views/Email/) to find the template.
2. Context Creation: Generates a DefaultHttpContext and ActionContext.
3. Dictionary Setup: Initializes ViewDataDictionary<T> with the provided model and TempDataDictionary.
4. Execution: Calls view.RenderAsync to write the HTML output into a StringWriter.

Sources: examples/RenderRazor/Controllers/EmailController.cs:88-140

Sequence of Operations

The sequence diagram below shows the interactions between the EmailController, the Razor engine, and the Resend SDK.

Usage Example

To send an email, you instantiate a model, render it to an HTML string, and assign that string to the HtmlBody of an EmailMessage.

var html = await RenderEmail( "Hello", new HelloModel()
{
    DisplayName = "John Doe",
    Items = { "NodeJs", "Go" },
    SenderName = "Resend Team",
} );

var message = new EmailMessage();
message.From = "you@domain.com";
message.To.Add( "user@gmail.com" );
message.Subject = "Hello from Render Razor";
message.HtmlBody = html;

await _resend.EmailSendAsync( message );

Sources: examples/RenderRazor/Controllers/EmailController.cs:52-82, README.md:126-147

Summary

Rendering emails with Razor views provides a robust way to handle complex HTML templates in .NET applications. By leveraging IRazorViewEngine within an API controller, you can generate content-rich emails that remain easy to test and maintain while utilizing the full delivery capabilities of the Resend SDK.

Sources: examples/RenderRazor/README.md:1-5, examples/README.md