Resolving SQL Data Persistence Issues in Xamarin.Forms Applications

Learn how to fix common SQL-related issues in Xamarin.Forms apps and ensure your data is displayed correctly using ViewModel bindings.
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This video is based on the question https://stackoverflow.com/q/69244251/ asked by the user 'Behzad Changizi' ( https://stackoverflow.com/u/16177336/ ) and on the answer https://stackoverflow.com/a/69245602/ provided by the user 'Jason' ( https://stackoverflow.com/u/1338/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Fixing SQL Data Persistence Issues in Xamarin.Forms Applications

Developing applications with Xamarin.Forms can sometimes lead to tricky data binding issues, especially when working with SQL databases. One common problem developers face is when they try to add items to a list, but the list remains empty. In this post, we will explore one user’s frustration with their Xamarin.Forms application and offer a comprehensive solution!

The Issue at Hand

A user reached out with a challenge: They created an interface where they wanted to add a new EnergyX object (representing X-ray data) to a list, but every time they did, the list displayed was empty. Despite their application reaching the end of the ViewModel, nothing seemed to reflect in the UI.

The code they provided included bindings for an Entry control for data input, a Button to trigger the addition of new data, and a ListView that should display these entries. However, the use of SQL for saving data seemed to have disrupted the expected behavior.

Understanding the Core Problem

The main culprit behind this issue lies in the way the ObservableCollection for the energyX list was being handled. Specifically, the following line was responsible for creating a new instance of energyX:

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

When this line is executed, it replaces the previous instance of energyX with a new one, which means any bindings previously made to the original instance are broken. That's why the ListView doesn’t display the newly added data.

Solution Breakdown

To resolve this issue, there are mainly two approaches to consider:

Option 1: Implement INotifyPropertyChanged

What is it? The INotifyPropertyChanged interface helps you raise notifications whenever a property changes, allowing your UI to respond to those changes automatically.

How to implement:

Here is how you can update your EnergyViewModel to support this:

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

Whenever you update the collection, simply raise the property changed event to inform the UI about the change.

Option 2: Modify Existing Collection

What to do: Instead of creating a new instance of energyX, simply add the new entry directly to the existing collection.

Code Example:

Modify your AddX() method like this:

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

Conclusion

By following either of the above options, you should be able to resolve the issue of your empty list in the ListView. Debugging is an essential part of development, and recognizing the interaction between your ViewModel and UI is crucial for ensuring data is displayed as expected.

Happy coding, and remember to always check how your collections are managed in Xamarin.Forms!

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