asset_saving.md

---

title: Asset Saving
authors: ["@andriyDev"]
pull_requests: []

---

Since Bevy 0.12, we've had the AssetSaver trait. Unfortunately, this trait was not really usable for asset saving: it was only intended for use with asset processing! This was a common stumbling block for users, and pointed to a gap in our API.

Now, users can save their assets using save_using_saver. To use this involves two steps.

1. Building the SavedAsset

To build the SavedAsset, either use SavedAsset::from_asset:

let main_asset = InlinedBook {
    lines: vec!["Save me!".to_string(), "Please!".to_string()],
};
let saved_asset = SavedAsset::from_asset(&main_asset);

Or for more complicated cases, SavedAssetBuilder:

let asset_path: AssetPath<'static> = "my/file/path.whatever";
let mut builder = SavedAssetBuilder::new(asset_server.clone(), asset_path.clone());

let subasset_1 = Line("howdy".into());
let subasset_2 = Line("goodbye".into());
let handle_1 = builder.add_labeled_asset_with_new_handle(
    "TheFirstLabel", SavedAsset::from_asset(&subasset_1));
let handle_2 = builder.add_labeled_asset_with_new_handle(
    "AnotherOne", SavedAsset::from_asset(&subasset_2));

let main_asset = Book {
    lines: vec![handle_1, handle_2],
};
let saved_asset = builder.build(&main_asset);

Note that since these assets are borrowed, building the SavedAsset should happen in the same async task as the next step.

2. Calling save_using_saver

Now, with a SavedAsset, we can just call save_using_saver and fill in any arguments:

save_using_saver(
    asset_server.clone(),
    &MyAssetSaver::default(),
    &asset_path,
    saved_asset,
    &MySettings::default(),
).await.unwrap();

Part of this includes implementing the AssetSaver trait on MyAssetSaver. In addition, this is an async function, so it is likely you will want to spawn this using IoTaskPool::get().spawn(...).