Best Practices for Data Persistence: Handling File I/O and Databases (Flutter vs. Rust)

[erflaber]

I would love to hear the community's thoughts (and hopefully a recommendation from the maintainers) on the best practices for saving files and handling databases.

The Core Question

When dealing with local storage (saving files, using SQL-like databases, etc.), should the logic be handled primarily from the Flutter (Dart) side or the Rust side?

Specific Scenarios

I can see arguments for both sides, but I'm unsure of the "canonical" approach for this architecture:

1. Database Handling (SQL):

   • Is it better to have Flutter handle db iteractions with packages(like sqflite or drift or is it better to use Rust with crates like rusqlite or diesel?

2. File I/O:

   • Is it safer to handle file writing/reading via Rust's std::fs, or should we stick to Flutter's dart:io?

3. Preferences:

   • Should I be storing app settings from Flutter via share_preferences or Rust via serde?

Path Management

This brings me to the second part of the question: Finding the right paths.

Mobile operating systems (especially iOS and Android) have strict sandboxing rules and specific directories for persistent data vs. cache.

• If we handle saving in Rust, how do we reliably find the correct application documents directory? Rust doesn't inherently know about Android's getExternalFilesDir or iOS's NSDocumentDirectory.
• Do we need to pass the path from Flutter to Rust as a string argument, or is there a preferred method for Rust to resolve these paths natively?

Proposal

I think it would be incredibly helpful if the documentation included a small "Architecture Recommendation" or "Best Practices" section regarding data persistence. A short guide on "Where to store your data" would save a lot of trial and error for new users.

Thanks in advance for the guidance and for the great work on the project. Long time fan here.

[temeddix]

Hi, thank you for your participation :)

As the documentation states, Rinf expects the whole business logic to be written in Rust, while Flutter serves only as the UI layer.

• https://rinf.cunarist.org/introduction/

Therefore it can be advised to put database connections as member vars of Rust "actors" or "tokio tasks".

To get platform directories, you can use dedicated crates such as sysdirs.

• https://crates.io/crates/sysdirs

These are my thoughts on your questions regarding using Rinf, but any opinions from the community is appreciated!