Why should you care?

Bad input stopped early keeps ShopNest safe and your database clean.

See it live — copy this example

Create an MVC project (dotnet new mvc), add the code, and run dotnet run.

// Data Annotations — ShopNest.Mvc example
public class HomeController : Controller
{
    public IActionResult Index() => View();
}

Run Example »

Edit the code and click Run — like W3Schools Try it Yourself.

What happened?

• Study the example line by line.
• Each part connects to Data Annotations.
• Edit one line, save, and run dotnet run to see what changes.

Try it yourself

1. Add the rule or model from the example.
2. Submit invalid data and confirm errors show.
3. Submit valid data and confirm save works.
4. Change text or labels in the example and run again — watch the browser update.
5. Break the code on purpose (remove a semicolon), read the error message, then fix it.

Remember

You learned what Data Annotations is and when to use it. Practice by changing the example yourself. Explain it in your own words before moving on.