**Course Title:** Mastering C#: From Fundamentals to Advanced Programming **Section Title:** Building Web Applications with ASP.NET Core **Topic:** Build a simple ASP.NET Core web application with routing and form handling.(Lab topic) **Overview** In this lab, you'll learn how to build a simple ASP.NET Core web application that handles routing and form submission. You'll create a basic application, define routes, create views, and handle form data. **Prerequisites** Before starting this lab, ensure you have the following: 1. .NET Core 6.0 or later installed on your machine 2. Visual Studio 2022 or later installed on your machine (Community Edition or higher) 3. Familiarity with C# and ASP.NET Core fundamentals **Step 1: Create a new ASP.NET Core project** Open Visual Studio and create a new project by selecting "File" -> "New" -> "Project...". In the "New Project" dialog box, select ".NET Core" under the "Visual C#" node, and then choose "ASP.NET Core Web Application" as the project type. Name your project "SimpleASPNETCoreApp" and ensure the ".NET Core" and "ASP.NET Core 6.0" options are selected. Click "OK" to create the project. **Step 2: Define routes** In ASP.NET Core, routes are defined in the `Startup.cs` file (for .NET Core 3.1 and earlier) or in the `Program.cs` file (for .NET Core 6.0 and later). For this lab, you'll use the `Program.cs` file. Open the `Program.cs` file and add the following code to define two routes: ```csharp var builder = WebApplication.CreateBuilder(args); // Add services to the container. builder.Services.AddControllersWithViews(); var app = builder.Build(); // Define routes app.MapGet("/", () => "Welcome to the Simple ASP.NET Core App!"); app.MapPost("/submit", () => "Form submitted successfully!"); app.Run(); ``` The first route handles GET requests to the root URL ("/") and returns a simple welcome message. The second route handles POST requests to the "/submit" URL and returns a message indicating that the form was submitted successfully. **Step 3: Create a view** Create a new folder called "Views" in the root of your project. Inside the "Views" folder, create a new folder called "Home". Inside the "Home" folder, create a new file called "Index.cshtml". In the `Index.cshtml` file, add the following code to create a simple form: ```html @{ ViewData["Title"] = "Simple ASP.NET Core App"; } <h1>Simple ASP.NET Core App</h1> <form method="post" action="/submit"> <label for="name">Enter your name:</label> <input type="text" id="name" name="name" required> <br><br> <input type="submit" value="Submit"> </form> ``` This form has a single input field for the user's name and a submit button. When the form is submitted, the browser will send a POST request to the "/submit" URL. **Step 4: Run the application** Run the application by clicking the "IIS Express" button in the Visual Studio toolbar or pressing F5. Open a web browser and navigate to the root URL of your application (e.g., `http://localhost:5000/`). You should see the welcome message displayed on the page. Enter some text in the form field and click the submit button. The browser will send a POST request to the "/submit" URL, and you should see the form submitted successfully message displayed on the page. **Conclusion** In this lab, you created a simple ASP.NET Core web application that handles routing and form submission. You defined routes, created views, and handled form data using the `MapGet` and `MapPost` methods. To learn more about ASP.NET Core, visit the official documentation: [https://docs.microsoft.com/en-us/aspnet/core/](https://docs.microsoft.com/en-us/aspnet/core/) If you have any questions or need help with this lab, feel free to ask in the comments section below. **Next Topic:** Introduction to unit testing with NUnit or xUnit (from the "Testing and Debugging in C#" section)