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    Best Practices for Structuring RTK Query API Slices in Large Applications

    When building large-scale applications, organizing RTK Query API slices properly ensures your codebase remains modular, maintainable, and easy to scale. A good structure helps with team collaboration, reusability, and performance.

    Recommended Best Practices
    • **1. Use a Feature-Based Approach:** Group endpoints by domain or feature (e.g., usersApi, postsApi) instead of having one massive API slice.
    • **2. Create a Shared Root API:** Define a common createApi instance (with shared baseQuery, headers, and tag types) and extend it with injectEndpoints for modularity.
    • **3. Use Consistent Tagging:** Define clear tagTypes to manage cache invalidation across different slices.
    • **4. Co-locate APIs with Features:** Place API files alongside their corresponding feature components and Redux slices for better discoverability.
    • **5. Keep API Logic Pure:** Avoid adding UI or business logic inside API definitions—use onQueryStarted only for small side effects like optimistic updates.
    • **6. Re-export Hooks:** Only export the generated hooks (e.g., useGetPostsQuery) from each API slice to keep imports clean and maintain encapsulation.
    • **7. Use TypeScript for Strong Typing:** Ensure your endpoints have typed request parameters and responses for better safety and autocompletion.
    Example: Modular RTK Query Structure

    This modular approach lets you split endpoints across files, improve code organization, and scale the app as it grows — while keeping all API logic under a consistent root.

    Key Benefits
    • **- Scalability:** Easily add or modify feature APIs without touching unrelated code.
    • **- Maintainability:** Clear structure improves readability and debugging.
    • **- Modularity:** Independent feature slices allow better code reuse and lazy loading.
    • **- Team Collaboration:** Different teams can safely manage different slices.

    Following these practices helps large applications stay efficient, organized, and easier to maintain as the codebase evolves.