C# 7 and .NET: Designing Modern Cross-platform Applications

Passing parameters using a route value

Back in the HomeController class, add an action method named ProductDetail, as shown in the following code:

public IActionResult ProductDetail(int? id) {    if (!id.HasValue)    {       return NotFound("You must pass a product ID in the route, for       example, /Home/ProductDetail/21");    }    var model = db.Products.SingleOrDefault(p => p.ProductID == id);    if (model == null)    {       return NotFound($"A product with the ID of {id} was not found.");    }    return View(model); // pass model to view } 

Note the following:

• This method uses a feature of ASP.NET Core called model binding to automatically match the id passed in the route to the parameter named id in the method
• Inside the method, we check to see whether id is null, ...