**Course Title:** .NET MAUI App Development **Section Title:** Navigation and Page Layouts **Topic:** Passing data between pages **Overview** In this topic, we'll explore the different ways to pass data between pages in a .NET MAUI app. We'll cover the most common techniques, including using the Navigation class, passing parameters through constructors, and using a shared view model. By the end of this topic, you'll be able to pass data between pages effectively and create a seamless user experience in your .NET MAUI app. **Passing Data using the Navigation Class** The `Navigation` class provides a simple way to pass data between pages using the `PushAsync` and `PopAsync` methods. You can pass data as a parameter to the `PushAsync` method, which navigates to the next page and returns the result. ```csharp // PushAsync with parameter await Navigation.PushAsync(new MyPage("Hello, Navigation!")); // PopAsync with result string result = await Navigation.PopAsync<string>(); ``` The receiving page can then access the data through its constructor or through a public property. ```csharp public class MyPage : ContentPage { public MyPage(string message) { Label label = new Label { Text = message }; Content = label; } } ``` **Passing Data using Constructors** Another way to pass data between pages is by using constructors. This method is useful when you need to pass a large amount of data or complex objects. ```csharp public class MyPage : ContentPage { public MyPage(User user) { Label label = new Label { Text = user.Name }; Content = label; } } // Passing data to the constructor await Navigation.PushAsync(new MyPage(new User { Name = "John Doe" })); ``` **Passing Data using a Shared View Model** Using a shared view model is a more advanced technique that allows you to share data between multiple pages. This method is useful when you need to share data between pages in a more complex scenario. ```csharp public class MyViewModel : INotifyPropertyChanged { public string Message { get; set; } public ICommand NavigateCommand { get; set; } public MyViewModel() { NavigateCommand = new Command(async () => { await Navigation.PushAsync(new MyPage()); }); } } public class MyPage : ContentPage { public MyPage(MyViewModel viewModel) { BindingContext = viewModel; } } // Using the shared view model to pass data await Navigation.PushAsync(new MyPage(viewModel)); ``` **Best Practices and Considerations** When passing data between pages, consider the following best practices and considerations: * Use the `Navigation` class for simple cases where you need to pass a small amount of data. * Use constructors for complex cases where you need to pass large amounts of data or complex objects. * Use a shared view model for complex scenarios where you need to share data between multiple pages. * Always validate the data received by the page to ensure it is in the expected format. **Practical Exercise** Try the following exercise to reinforce your understanding of passing data between pages: 1. Create a new .NET MAUI app. 2. Create two pages: `MyPage1` and `MyPage2`. 3. Use the `Navigation` class to pass a string from `MyPage1` to `MyPage2`. 4. Use a constructor to pass a complex object from `MyPage1` to `MyPage2`. 5. Use a shared view model to share data between the two pages. **Additional Resources** * [.NET MAUI Documentation: Navigation](https://learn.microsoft.com/en-us/dotnet/maui/fundamentals/navigation) * [.NET MAUI Documentation: Using MVVM](https://learn.microsoft.com/en-us/dotnet/maui/xaml/mvvm) **Leave a Comment/Ask for Help** If you have any questions or need help with any of the concepts covered in this topic, please leave a comment below.