—

## Quick start

Tauri is shipped with **state management** function/feature by default.

Basic usage is quite simple: a variable of State type can be accessed on the _tauri commands_ which you have defined; in other words, "with tauri commands, they'll magically inject state for you," so that once a variable is **managed** you can inject them directly as additional input when defining the command.

### Example Implementation

In this example, our front-end passes a path variable to the bakcend via `retrieve_scroll` command [which is [custom command](https://tauri.studio/v1/guides/features/command) we defined];

0. Require respective modules:

```rust
use std::sync::Mutex;
use tauri::State;
```

1. Declare a stract holding the variable you would like to share across your `commands`:

```rust
struct Note(Mutex<String>);
```

2. Initialize it in the `main()` function by chaining `manager()` to `tauri`:

```rust
 tauri::Builder::default()
  .manage(Note(Default::default()))
  .invoke_handler(tauri::generate_handler![
    retrieve_scroll,
  ])
  .run(tauri::generate_context!())
  .expect("error while running tauri application");
```

3. Access your variable by adding an additional input:

```rust
fn retrieve_scroll(path: &str, note: State<Note>) -> String{
  let mut nt = note.0.lock().unwrap();
  let mut base = PathBuf::from(path);
  *nt = base.display().to_string();
```

4. Now if you add `note: State<Note>` to your inputs in other commands, you will get the value that is stored in memory refernced by the `note` instance in the backend, so, you don't need to pass the `path` value from the front-end anymore. That is, of course, if you have to change the value of the `path`.

## Questions / Todos

- what is the extend of "manager". I couldn't really find any docs on https://tauri.studio
- why are we indexing 0 when unlocking the struct?

> Because Note is a "tuple struct" (https://doc.rust-lang.org/rust-by-example/custom_types/structs.html) and the Mutex is the first item of the tuple; indexes generally start at 0 therefore we use note.0 to tell rust that we want the Mutex from the struct
> 
> By FabianLars

## Disclaimer

This is note for personal reference, also encouragement for others [more experienced, skilled, educated] to delve into more detailed on managing states in a Rust application.

The **aspiration** is to have a booklet which _teaches best practices in state management_ specifically for applications:

- desgined with a front-end back-end architecture paradigm
- feature / scalable to function entirely offline / online / [auto] sync (read it "hybrid")
- ...

## Refrences

- Discord answer by (DCEDDIA). https://discord.com/channels/616186924390023171/622768087183130673/975567244358742016
- Nakamura, Mar-M. "Trying to the Tauri GUI on Rust : 4. State management on the Rust side." https://medium.com/@marm.nakamura/trying-to-the-tauri-gui-on-rust-4-state-management-on-the-rust-side-8899bda08936.