How to Dynamically Call ViewModel with Different Parameters in Jetpack Compose?

Learn how to effectively call a ViewModel dynamically based on user-selected parameters in Jetpack Compose, ensuring your UI updates correctly with new data from Firestore.
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How to Dynamically Call ViewModel with Different Parameters in Jetpack Compose?

When developing Android applications using Jetpack Compose, you might face challenges when dynamically managing data sources, particularly while integrating with Firestore. One common issue developers encounter is retrieving updated data when certain parameters are changed, for instance, when users interact with a dropdown menu. In this guide, we will explore how to effectively call a ViewModel dynamically based on user-selected parameters in Jetpack Compose.

Understanding the Problem

In your application, you have a dropdown menu where users can select different options. This selection is supposed to use a specific parameter (pompaId) to request data from Firestore through a ViewModel. However, once the ViewModel is created, it's not reflecting the changes in the pompaId when the dropdown selection changes. As a result, the data retrieval from Firestore does not occur as expected, leading to empty or stale data being shown in your UI.

The Solution

To resolve this issue, we can leverage the key parameter available in the viewModel function. By providing a unique key for each instance of the ViewModel (in this case, pompaId), we ensure that a new ViewModel instance is created for each unique value. This way, it reflects the current state based on the user's selection.

Step-by-Step Implementation

Let’s break down the implementation into clear steps:

Modify the ViewModel Call: Change your KalibrasiList function to utilize the key parameter.

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

Dropdown Interaction: Ensure your dropdown correctly updates pompaId upon selection.

When the user selects a dropdown item, update the selectedText and pompaId as before.

The modified pompaId will automatically trigger the composition of KalibrasiList with a new ViewModel created for the new key.

ViewModelFactory and Repository: Keep your ViewModel and Repository classes unchanged, as they are functioning correctly to fetch the data from Firestore.

Why This Works

Using the key parameter ensures that each time pompaId changes, a new instance of KalibrasiViewModel is created. This instance listens to Firestore using the new parameter, which means your UI can reactively display the correct data.

Conclusion

Managing dynamic parameters in Jetpack Compose while calling ViewModels may seem tricky at first, but by leveraging the key parameter in the viewModel function, you can ensure fresh data retrieval every time the user interacts with your UI. This approach not only resolves the issue of stale data but also ensures a responsive and user-friendly application.

Don’t hesitate to experiment with your implementation, and see how dynamic parameter handling can enhance your app's functionality!