Struct AssetLoadingState 

pub struct AssetLoadingState<K: AssetKey> { /* private fields */ }

Loading state with asset key information for error reporting.

This is returned by Db::asset_state() and provides information about whether an asset is loading or ready.

For most use cases, prefer Db::asset() which automatically suspends on loading. Use asset_state() when you need to explicitly check the loading state without triggering suspension.

Example

use query_flow::{asset_key, query, Db, DurabilityLevel, QueryError, QueryRuntime};

#[asset_key(asset = String)]
struct FilePath(String);

#[query]
fn process_file(db: &impl Db, path: FilePath) -> Result<usize, QueryError> {
    // Most common: just use db.asset() which suspends automatically
    let content = db.asset(path)?;
    Ok(content.len())
}

#[query]
fn check_loading(db: &impl Db, path: FilePath) -> Result<bool, QueryError> {
    // Use asset_state() when you need to check loading status explicitly
    let state = db.asset_state(path)?;
    Ok(state.is_loading())
}

let runtime = QueryRuntime::new();
runtime.resolve_asset(
    FilePath("a".into()),
    "hello".into(),
    DurabilityLevel::Volatile,
);
assert_eq!(*runtime.query(ProcessFile::new(FilePath("a".into()))).unwrap(), 5);
assert!(!*runtime.query(CheckLoading::new(FilePath("a".into()))).unwrap());

Implementations

impl<K: AssetKey> AssetLoadingState<K>

pub fn loading(key: K) -> Self

Create a loading state (asset not yet available).

pub fn ready(key: K, value: Arc<K::Asset>) -> Self

Create a ready state with the asset value.

pub fn is_loading(&self) -> bool

Check if the resource is still loading.

pub fn is_ready(&self) -> bool

Check if the resource is ready.

pub fn get(&self) -> Option<&Arc<K::Asset>>

Get the value if ready, None if loading.

pub fn into_inner(self) -> Option<Arc<K::Asset>>

Get the value if ready, None if loading (consuming version).

pub fn suspend(self) -> Result<Arc<K::Asset>, QueryError>

Convert to Result - Loading becomes Err(QueryError::Suspend).

This method is used internally by Db::asset(). You can also use it when working with Db::asset_state().

Example

use query_flow::{asset_key, query, Db, DurabilityLevel, QueryError, QueryRuntime};

#[asset_key(asset = String)]
struct FilePath(String);

#[query]
fn byte_len(db: &impl Db, path: FilePath) -> Result<usize, QueryError> {
    // Preferred: use db.asset() directly
    let data = db.asset(path.clone())?;

    // Alternative: use asset_state() + suspend()
    let state = db.asset_state(path)?;
    let data2 = state.suspend()?;

    assert_eq!(data, data2);
    Ok(data.len())
}

let runtime = QueryRuntime::new();
runtime.resolve_asset(
    FilePath("a".into()),
    "hello".into(),
    DurabilityLevel::Volatile,
);
assert_eq!(*runtime.query(ByteLen::new(FilePath("a".into()))).unwrap(), 5);

pub fn key(&self) -> &K

Get a reference to the key.

Trait Implementations

impl<K: AssetKey> Debug for AssetLoadingState<K>

where K::Asset: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.