Accessing file in rust

[dev-mash]

I'm new to rust and tauri. I currently write some data to a file using the file api (in javascript). Now I need to read the file data in my main.rs. What is the best approach to access the filesystem from my rust code?
Is there a way to call my javascript/the javascript file-api from the main.js or is there a rust-api where I can similiary access the filesystem folders?

Example:
In javascript I write to $APPDATA/users directory using the constants BaseDirectory.AppData:
https://tauri.app/v1/api/js/fs/#createdir

How could I read this folder from main.js? And is there some way to call my javascript code from main,js?

Thanks in advance &
Best regards,
Manuel

[FabianLars]

How could I read this folder from main.js?

https://doc.rust-lang.org/std/fs/struct.File.html#examples (second one is for reading) + tauri's PathResolver so a minimal example using the setup hook (which runs on app start so potentially useless idk)

tauri::Builder::default()
  .setup(|app| {
    let dir = app.path_resolver().app_data_dir().expect("couldn't resolve app data dir").join("users/");
    // you may want to check if the dir and/or files exist first
    // also the unwraps should be replaced with proper error handling
    // if you want to get the file as binary, just remove the from_utf8_lossy call.
    let contents = String::from_utf8_lossy(&std::fs::read("address.txt").unwrap()).parse().unwrap();
    
    Ok(())
  })

If you need this somewhere where you don't have access to an AppHandle or Window, you could tauri::path::data_dir() and add your bundle identifier as a folder to that (this is what appdatadir is)

And is there some way to call my javascript code from main,js?

The "most intended" way is to use tauri events https://tauri.app/v1/guides/features/events/

[dev-mash]

Thanks for the example and the link!