Getting Started

Getting started

This guide creates a minimal ASP.NET Core application whose /hello URL maps to a Hello page class.

Requirements

• A .NET 8 or .NET 10 SDK and ASP.NET Core application
• The KitchenPC.Imp package

dotnet new web --name HelloImp
cd HelloImp
dotnet add package KitchenPC.Imp

This installs the latest stable package. Pin an explicit version in applications that require reproducible restores.

Imp 0.2 and later uses the ASP.NET Core shared framework rather than carrying obsolete server packages inside the NuGet package. ASP.NET Core Web projects reference that framework automatically.

Configure the middleware

Replace Program.cs with:

using Imp;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.UseStaticFiles();
app.UseImp(config => config
   .PageAssembly(typeof(Program).Assembly)
   .RootPageNamespace("HelloImp.Pages"));

app.Run();

Imp is terminal middleware: it handles the request and does not invoke middleware registered after it. Put exception handling, authentication, authorization, and static-file handling before UseImp.

Create a page

Add Pages/Hello.cs:

using System.Text.Encodings.Web;
using Imp;

namespace HelloImp.Pages;

public sealed class Hello : BasePage
{
   public string Name { get; set; } = "World";

   public override Task Render(HttpResponse response)
   {
      var name = HtmlEncoder.Default.Encode(Name);
      return response.WriteAsync($"<h1>Hello, {name}!</h1>");
   }
}

Run the application:

dotnet run

• /hello maps to HelloImp.Pages.Hello.
• /hello?Name=Mike binds Name and renders Hello, Mike!.
• / maps to a class named HelloImp.Pages.Default.

Always encode request-derived text before writing HTML. Query binding converts values; it does not perform output encoding or validation.

Add a custom 404 page

public sealed class NotFound : BasePage
{
   public override void PreRender(HttpResponse response) =>
      response.StatusCode = StatusCodes.Status404NotFound;

   public override Task Render(HttpResponse response) =>
      response.WriteAsync("<h1>Page not found</h1>");
}

Register it:

.NotFoundPageType<HelloImp.Pages.NotFound>()

Next steps

• Move HTML into embedded templates and layouts.
• Learn the exact request lifecycle.
• Run the complete Todo sample.