Struct OnceResource

pub struct OnceResource<T, Ser = JsonSerdeCodec> { /* private fields */ }

A resource that only loads once.

Resources allow asynchronously loading data and serializing it from the server to the client, so that it loads on the server, and is then deserialized on the client. This improves performance by beginning data loading on the server when the request is made, rather than beginning it on the client after WASM has been loaded.

You can access the value of the resource either synchronously using .get() or asynchronously using .await.

Implementations

impl<T, Ser> OnceResource<T, Ser>

where T: Send + Sync + 'static, Ser: Encoder<T> + Decoder<T>, <Ser as Encoder<T>>::Error: Debug, <Ser as Decoder<T>>::Error: Debug, <<Ser as Decoder<T>>::Encoded as FromEncodedStr>::DecodingError: Debug, <Ser as Encoder<T>>::Encoded: IntoEncodedString, <Ser as Decoder<T>>::Encoded: FromEncodedStr,

pub fn new_with_options( fut: impl Future<Output = T> + Send + 'static, blocking: bool, ) -> Self

Creates a new resource with the encoding Ser. If blocking is true, this is a blocking resource.

Blocking resources prevent any of the HTTP response from being sent until they have loaded. This is useful if you need their data to set HTML document metadata or information that needs to appear in HTTP headers.

pub fn map<U>(&self, f: impl FnOnce(&T) -> U) -> Option<U>

Synchronously, reactively reads the current value of the resource and applies the function f to its value if it is Some(_).

impl<T, E, Ser> OnceResource<Result<T, E>, Ser>

where Ser: Encoder<Result<T, E>> + Decoder<Result<T, E>>, <Ser as Encoder<Result<T, E>>>::Error: Debug, <Ser as Decoder<Result<T, E>>>::Error: Debug, <<Ser as Decoder<Result<T, E>>>::Encoded as FromEncodedStr>::DecodingError: Debug, <Ser as Encoder<Result<T, E>>>::Encoded: IntoEncodedString, <Ser as Decoder<Result<T, E>>>::Encoded: FromEncodedStr, T: Send + Sync + 'static, E: Send + Sync + Clone + 'static,

pub fn and_then<U>(&self, f: impl FnOnce(&T) -> U) -> Option<Result<U, E>>

Applies the given function when a resource that returns Result<T, E> has resolved and loaded an Ok(_), rather than requiring nested .map() calls over the Option<Result<_, _>> returned by the resource.

This is useful when used with features like server functions, in conjunction with <ErrorBoundary/> and <Suspense/>, when these other components are left to handle the None and Err(_) states.

impl<T, Ser> OnceResource<T, Ser>

where T: Send + Sync + 'static, Ser: 'static,

pub fn ready(&self) -> AsyncDerivedReadyFuture

Returns a Future that is ready when this resource has next finished loading.

impl<T> OnceResource<T, JsonSerdeCodec>

where T: Send + Sync + 'static, JsonSerdeCodec: Encoder<T> + Decoder<T>, <JsonSerdeCodec as Encoder<T>>::Error: Debug, <JsonSerdeCodec as Decoder<T>>::Error: Debug, <<JsonSerdeCodec as Decoder<T>>::Encoded as FromEncodedStr>::DecodingError: Debug, <JsonSerdeCodec as Encoder<T>>::Encoded: IntoEncodedString, <JsonSerdeCodec as Decoder<T>>::Encoded: FromEncodedStr,

pub fn new(fut: impl Future<Output = T> + Send + 'static) -> Self

Creates a resource using JsonSerdeCodec for encoding/decoding the value.

pub fn new_blocking(fut: impl Future<Output = T> + Send + 'static) -> Self

Creates a blocking resource using JsonSerdeCodec for encoding/decoding the value.

Blocking resources prevent any of the HTTP response from being sent until they have loaded. This is useful if you need their data to set HTML document metadata or information that needs to appear in HTTP headers.

impl<T> OnceResource<T, FromToStringCodec>

where T: Send + Sync + 'static, FromToStringCodec: Encoder<T> + Decoder<T>, <FromToStringCodec as Encoder<T>>::Error: Debug, <FromToStringCodec as Decoder<T>>::Error: Debug, <<FromToStringCodec as Decoder<T>>::Encoded as FromEncodedStr>::DecodingError: Debug, <FromToStringCodec as Encoder<T>>::Encoded: IntoEncodedString, <FromToStringCodec as Decoder<T>>::Encoded: FromEncodedStr,

pub fn new_str(fut: impl Future<Output = T> + Send + 'static) -> Self

Creates a resource using FromToStringCodec for encoding/decoding the value.

pub fn new_str_blocking(fut: impl Future<Output = T> + Send + 'static) -> Self

Creates a blocking resource using FromToStringCodec for encoding/decoding the value.

Blocking resources prevent any of the HTTP response from being sent until they have loaded. This is useful if you need their data to set HTML document metadata or information that needs to appear in HTTP headers.

Trait Implementations

impl<T, Ser> Clone for OnceResource<T, Ser>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug, Ser: Debug> Debug for OnceResource<T, Ser>

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

Formats the value using the given formatter.

impl<T, Ser> DefinedAt for OnceResource<T, Ser>

fn defined_at(&self) -> Option<&'static Location<'static>>

Returns the location at which the signal was defined. This is usually simply None in release mode.

impl<T, Ser> IntoFuture for OnceResource<T, Ser>

where T: Clone + Send + Sync + 'static, Ser: 'static,

type Output = T

The output that the future will produce on completion.

type IntoFuture = OnceResourceFuture<T>

Which kind of future are we turning this into?

fn into_future(self) -> Self::IntoFuture

Creates a future from a value.

impl<T, Ser> IsDisposed for OnceResource<T, Ser>

fn is_disposed(&self) -> bool

If true, the signal cannot be accessed without a panic.

impl<T, Ser> ReadUntracked for OnceResource<T, Ser>

where T: Send + Sync + 'static, Ser: 'static,

type Value = ReadGuard<Option<T>, Plain<Option<T>>>

The guard type that will be returned, which can be dereferenced to the value.

fn try_read_untracked(&self) -> Option<Self::Value>

Returns the guard, or None if the signal has already been disposed.

fn read_untracked(&self) -> Self::Value

Returns the guard.

fn custom_try_read(&self) -> Option<Option<Self::Value>>

This is a backdoor to allow overriding the Read::try_read implementation despite it being auto implemented.

impl<T, Ser> ToAnySource for OnceResource<T, Ser>

where T: Send + Sync + 'static, Ser: 'static,

fn to_any_source(&self) -> AnySource

Converts this type to its type-erased equivalent.

impl<T, Ser> Track for OnceResource<T, Ser>

where T: Send + Sync + 'static, Ser: 'static,

fn track(&self)

Subscribes to this signal in the current reactive scope without doing anything with its value.

impl<T, Ser> Copy for OnceResource<T, Ser>