How to Ensure Data Persistence Between Pages in Xamarin.Forms Shell

Описание: Discover a straightforward solution to keep user input data persistent when navigating back in `Xamarin.Forms` Shell applications.
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This video is based on the question https://stackoverflow.com/q/69810164/ asked by the user 'Sk93' ( https://stackoverflow.com/u/148424/ ) and on the answer https://stackoverflow.com/a/69836107/ provided by the user 'Sk93' ( https://stackoverflow.com/u/148424/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Navigating Back Doesn’t Remember Entered Data: A Common Issue in Xamarin.Forms Shell

In the realm of mobile application development, creating a seamless and user-friendly experience is critical. One common challenge developers face is ensuring that user input data persists correctly as users navigate between pages. This issue arises particularly when using Xamarin.Forms Shell, where navigating back to a previously filled form does not reflect the user’s changes.

For instance, consider a login flow that consists of two pages: one for the email address and another for the password. When a user enters their email on the first page, proceeds to enter their password on the second page, and then goes back to the email page, they expect to see the updated email. Unfortunately, if the first page was loaded with a query parameter, it may revert to its original state, causing frustration.

Understanding the Problem

In your implementation, when navigating to the first page, the email address is passed as a query parameter. This can be problematic if you want your users to modify their input. Here’s a simplified depiction of the behavior:

Without Query Parameter:

User opens page → Email text box is blank → User enters email → Goes to next page → Returns → Email text box shows the entered email.

With Query Parameter:

User opens page with email Hello (as a parameter) → Email text box shows the passed email → User changes it → Goes to next page → Returns → Email text box reverts to the original passed email.

Solution to the Problem

To maintain user input, a simple workaround involves storing the current email address while navigating through pages. Let’s break down the solution.

Step 1: Storing the Edited Email Address

You will need to add logic to the first page's code-behind to temporarily store the email address when the page is disappearing:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Code

OnAppearing Method: This method is invoked when the page appears. Here, we check if there’s a previously edited email address. If there is, we set the ViewModel.EmailAddress to the edited email.

OnDisappearing Method: This method is called when the page is disappearing. We store the current email address from the ViewModel into EditedEmailAddress so that it can be retrieved when the page appears again.

Important Caveat

This approach works well for the email address field; however, note that if the email address is changed in the second page or any further edits are made, this method may not retain those changes. But if your main goal is to remember the changes made on the first page while navigating back from the second, this solution will work perfectly for your needs.

Conclusion

By implementing this straightforward approach, you can enhance the user experience in your Xamarin.Forms Shell applications by ensuring that user input data persists across navigation. Every change the user makes can be maintained rather than reverted to the initial state, reducing user frustration and improving overall usability.

For developers working with Xamarin.Forms Shell, this solution provides a practical approach to managing data persistence during navigation. Implementing these changes will undoubtedly lead to a more polished login process for your users.