Using SQLite instead of disk storage for egui app state

[UnknownSuperficialNight]

I have a SQLite DB and I would rather store the persistence data in there and then read from there on startup than storing it on disk.

I found Save from eframe but from my knowledge this is for disk storage only.

Is there any way to read and save the memory state to a DB upon startup/exit?

[YgorSouza]

It does not seem to be possible. Apparently eframe only lets you customize the path, but it always loads from a RON file stored on disk, like here:

egui/crates/eframe/src/native/glow_integration.rs

Lines 193 to 209 in 0db56dc

	fn init_run_state(
	&mut self,
	event_loop: &ActiveEventLoop,
	) -> Result<&mut GlowWinitRunning<'app>> {
	profiling::function_scope!();
	let storage = if let Some(file) = &self.native_options.persistence_path {
	epi_integration::create_storage_with_file(file)
	} else {
	epi_integration::create_storage(
	self.native_options
	.viewport
	.app_id
	.as_ref()
	.unwrap_or(&self.app_name),
	)
	};

egui/crates/eframe/src/native/epi_integration.rs

Lines 130 to 147 in 0db56dc

	/// For loading/saving app state and/or egui memory to disk.
	pub fn create_storage(_app_name: &str) -> Option<Box<dyn epi::Storage>> {
	#[cfg(feature = "persistence")]
	if let Some(storage) = super::file_storage::FileStorage::from_app_id(_app_name) {
	return Some(Box::new(storage));
	}
	None
	}
	#[allow(clippy::unnecessary_wraps)]
	pub fn create_storage_with_file(_file: impl Into<PathBuf>) -> Option<Box<dyn epi::Storage>> {
	#[cfg(feature = "persistence")]
	return Some(Box::new(
	super::file_storage::FileStorage::from_ron_filepath(_file),
	));
	#[cfg(not(feature = "persistence"))]
	None
	}

But it could be an idea. Instead of (or in addition to) taking a persistence_path, it could take a Box<dyn Fn> which overrides this create_storage function, so you could make it return your own SqliteStorage instead of a FileStorage. It doesn't seem to require big changes to eframe to make that happen, so you could open an issue if you want, to see if anyone is interested and discuss the implementations details.