[JetNews] Implement SavedStateHandle for selectedPostId persistence

[xingarr]

Description

This PR addresses the TODO comment in HomeViewModel.kt by implementing SavedStateHandle to persist the selectedPostId across process death and configuration changes.

Problem

Previously, the selectedPostId was stored only in memory within HomeViewModelState. When Android's system killed the app process to reclaim memory (process death), this state would be lost, causing users to lose their selected article when returning to the app.

Solution

Implemented SavedStateHandle to persist the selectedPostId, following Android's recommended architecture patterns for state preservation.

Changes Made

HomeViewModel.kt

• ✅ Added SavedStateHandle as a constructor parameter
• ✅ Created StateFlow backed by SavedStateHandle for persistent storage
• ✅ Added observer to react to SavedStateHandle changes
• ✅ Simplified interactedWithArticleDetails() to directly save to SavedStateHandle
• ✅ Modernized ViewModel factory using viewModelFactory DSL
• ✅ Removed TODO comment

Key Implementation Details

// StateFlow backed by SavedStateHandle for persistence
private val selectedPostIdState: StateFlow<String?> = savedStateHandle.getStateFlow(
    key = SELECTED_POST_ID_KEY,
    initialValue = preSelectedPostId,
)

// Direct save to SavedStateHandle
fun interactedWithArticleDetails(postId: String) {
    savedStateHandle[SELECTED_POST_ID_KEY] = postId
}

[gemini-code-assist[bot]]

Summary of Changes

Hello @xingarr, I'm Gemini Code Assist[^1]! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the JetNews application by ensuring the selectedPostId state is reliably preserved across Android process deaths and configuration changes. By integrating SavedStateHandle into the HomeViewModel, the application prevents users from losing their selected article when the Android system reclaims memory or during device rotations, thereby providing a more robust and seamless user experience.

Highlights

• State Persistence: Implemented SavedStateHandle in HomeViewModel to persist selectedPostId across process death and configuration changes, addressing a previous TODO comment.
• Architecture Update: Modernized the HomeViewModel factory using the viewModelFactory DSL for improved dependency injection and lifecycle management.
• Code Refinement: Simplified the interactedWithArticleDetails function to directly update the SavedStateHandle, ensuring consistent state management.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with :thumbsup: and :thumbsdown: on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

[^1]: Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution.