Implement minimal asset saving

.gitignore

@@ -25,6 +25,7 @@ imported_assets
 .web-asset-cache
 examples/large_scenes/bistro/assets/*
 examples/large_scenes/caldera_hotel/assets/*
+examples/asset/saved_assets
 
 # Bevy Examples
 example_showcase_config.ron

Cargo.toml

@@ -2015,6 +2015,18 @@ description = "Demonstrates various methods to load assets"
 category = "Assets"
 wasm = false
 
+[[example]]
+name = "asset_saving"
+path = "examples/asset/asset_saving.rs"
+doc-scrape-examples = true
+required-features = ["bevy_picking", "sprite_picking"]
+
+[package.metadata.example.asset_saving]
+name = "Asset Saving"
+description = "Demonstrates how to save an asset (with subassets)"
+category = "Assets"
+wasm = true
+
 [[example]]
 name = "asset_settings"
 path = "examples/asset/asset_settings.rs"

crates/bevy_asset/src/processor/process.rs

@@ -16,6 +16,7 @@ use alloc::{
     string::{String, ToString},
     vec::Vec,
 };
+use bevy_ecs::error::BevyError;
 use bevy_reflect::TypePath;
 use bevy_tasks::{BoxedFuture, ConditionalSendFuture};
 use core::marker::PhantomData;
@@ -160,7 +161,7 @@ pub enum ProcessError {
     WrongMetaType,
     #[error("Encountered an error while saving the asset: {0}")]
     #[from(ignore)]
-    AssetSaveError(Box<dyn core::error::Error + Send + Sync + 'static>),
+    AssetSaveError(BevyError),
     #[error("Encountered an error while transforming the asset: {0}")]
     #[from(ignore)]
     AssetTransformError(Box<dyn core::error::Error + Send + Sync + 'static>),

crates/bevy_asset/src/processor/tests.rs

@@ -32,7 +32,7 @@ use crate::{
         AssetProcessor, GetProcessorError, LoadTransformAndSave, LogEntry, Process, ProcessContext,
         ProcessError, ProcessorState, ProcessorTransactionLog, ProcessorTransactionLogFactory,
     },
-    saver::AssetSaver,
+    saver::{tests::CoolTextSaver, AssetSaver},
     tests::{
         read_asset_as_string, read_meta_as_string, run_app_until, CoolText, CoolTextLoader,
         CoolTextRon, SubText,
@@ -426,43 +426,6 @@ fn run_app_until_finished_processing(app: &mut App, guard: RwLockWriteGuard<'_,
     });
 }
 
-#[derive(TypePath)]
-struct CoolTextSaver;
-
-impl AssetSaver for CoolTextSaver {
-    type Asset = CoolText;
-    type Settings = ();
-    type OutputLoader = CoolTextLoader;
-    type Error = std::io::Error;
-
-    async fn save(
-        &self,
-        writer: &mut crate::io::Writer,
-        asset: crate::saver::SavedAsset<'_, Self::Asset>,
-        _: &Self::Settings,
-    ) -> Result<(), Self::Error> {
-        let ron = CoolTextRon {
-            text: asset.text.clone(),
-            sub_texts: asset
-                .iter_labels()
-                .map(|label| asset.get_labeled::<SubText, _>(label).unwrap().text.clone())
-                .collect(),
-            dependencies: asset
-                .dependencies
-                .iter()
-                .map(|handle| handle.path().unwrap().path())
-                .map(|path| path.to_str().unwrap().to_string())
-                .collect(),
-            // NOTE: We can't handle embedded dependencies in any way, since we need to write to
-            // another file to do so.
-            embedded_dependencies: vec![],
-        };
-        let ron = ron::ser::to_string_pretty(&ron, PrettyConfig::new().new_line("\n")).unwrap();
-        writer.write_all(ron.as_bytes()).await?;
-        Ok(())
-    }
-}
-
 // Note: while we allow any Fn, since closures are unnameable types, creating a processor with a
 // closure cannot be used (since we need to include the name of the transformer in the meta
 // file).
@@ -637,7 +600,7 @@ fn asset_processor_transforms_asset_with_meta() {
     source_dir.insert_meta_text(path, r#"(
     meta_format_version: "1.0",
     asset: Process(
-        processor: "bevy_asset::processor::process::LoadTransformAndSave<bevy_asset::tests::CoolTextLoader, bevy_asset::processor::tests::RootAssetTransformer<bevy_asset::processor::tests::AddText, bevy_asset::tests::CoolText>, bevy_asset::processor::tests::CoolTextSaver>",
+        processor: "bevy_asset::processor::process::LoadTransformAndSave<bevy_asset::tests::CoolTextLoader, bevy_asset::processor::tests::RootAssetTransformer<bevy_asset::processor::tests::AddText, bevy_asset::tests::CoolText>, bevy_asset::saver::tests::CoolTextSaver>",
         settings: (
             loader_settings: (),
             transformer_settings: (),
@@ -846,7 +809,7 @@ impl AssetSaver for FakeBsnSaver {
     async fn save(
         &self,
         writer: &mut crate::io::Writer,
-        asset: crate::saver::SavedAsset<'_, Self::Asset>,
+        asset: crate::saver::SavedAsset<'_, '_, Self::Asset>,
         _settings: &Self::Settings,
     ) -> Result<(), Self::Error> {
         use std::io::{Error, ErrorKind};
@@ -1336,7 +1299,7 @@ fn nested_loads_of_processed_asset_reprocesses_on_reload() {
         async fn save(
             &self,
             writer: &mut crate::io::Writer,
-            asset: crate::saver::SavedAsset<'_, Self::Asset>,
+            asset: crate::saver::SavedAsset<'_, '_, Self::Asset>,
             _settings: &Self::Settings,
         ) -> Result<<Self::OutputLoader as AssetLoader>::Settings, Self::Error> {
             let serialized = serialize_as_leaf(asset.get().value.clone());
@@ -1557,6 +1520,8 @@ fn only_reprocesses_wrong_hash_on_startup() {
             }
             asset.text.push(' ');
             asset.text.push_str(&asset.embedded);
+            // Clear the embedded text so that saving doesn't break.
+            asset.embedded.clear();
         }
     }
 
@@ -1759,7 +1724,7 @@ fn writes_default_meta_for_processor() {
         r#"(
     meta_format_version: "1.0",
     asset: Process(
-        processor: "bevy_asset::processor::process::LoadTransformAndSave<bevy_asset::tests::CoolTextLoader, bevy_asset::processor::tests::RootAssetTransformer<bevy_asset::processor::tests::AddText, bevy_asset::tests::CoolText>, bevy_asset::processor::tests::CoolTextSaver>",
+        processor: "bevy_asset::processor::process::LoadTransformAndSave<bevy_asset::tests::CoolTextLoader, bevy_asset::processor::tests::RootAssetTransformer<bevy_asset::processor::tests::AddText, bevy_asset::tests::CoolText>, bevy_asset::saver::tests::CoolTextSaver>",
         settings: (
             loader_settings: (),
             transformer_settings: (),