Enum DataResource 

pub enum DataResource<T> {
    Empty,
    Loading,
    Loaded(T),
    Failed(String),
}

Represents the lifecycle of async-loaded data.

This type captures the four states data can be in:

• Empty: No data requested yet
• Loading: Data is being fetched
• Loaded(T): Data successfully loaded
• Failed(String): Loading failed with error message

Variants

Empty

No data requested yet

Loading

Data is being fetched

Loaded(T)

Data successfully loaded

Failed(String)

Loading failed with error message

Implementations

impl<T> DataResource<T>

pub fn is_empty(&self) -> bool

Returns true if this is Empty.

pub fn is_loading(&self) -> bool

Returns true if this is Loading.

pub fn is_loaded(&self) -> bool

Returns true if this is Loaded(_).

pub fn is_failed(&self) -> bool

Returns true if this is Failed(_).

pub fn data(&self) -> Option<&T>

Returns a reference to the loaded data, or None if not loaded.

pub fn data_mut(&mut self) -> Option<&mut T>

Returns a mutable reference to the loaded data, or None if not loaded.

pub fn error(&self) -> Option<&str>

Returns the error message if failed, or None otherwise.

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

Maps the loaded value using the provided function.

If Loaded(t), returns Loaded(f(t)). Otherwise returns the same state.

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

Maps a reference to the loaded value.

pub fn and_then<U>( self, f: impl FnOnce(T) -> DataResource<U>, ) -> DataResource<U>

Applies a function that returns a DataResource to the loaded value.

Useful for chaining dependent async operations.

pub fn unwrap_or(self, default: T) -> T

Returns the loaded value or a default.

pub fn unwrap_or_else(self, f: impl FnOnce() -> T) -> T

Returns the loaded value or computes a default.

pub fn as_ref(&self) -> DataResource<&T>

Converts from &DataResource<T> to DataResource<&T>.

pub fn is_settled(&self) -> bool

Returns true if there’s either data or an error (not empty or loading).

pub fn is_pending(&self) -> bool

Returns true if there’s no data yet (empty or loading).

pub fn start_loading(&mut self) -> bool

where T: Clone,

Transitions to Loading state. Returns true if state actually changed.

Useful in reducers to start a fetch:

if resource.start_loading() {
    // dispatch effect to fetch
}

impl<T> DataResource<T>

where T: Clone,

pub fn cloned(&self) -> Option<T>

Returns a clone of the loaded data, or None if not loaded.

Trait Implementations

impl<T> Clone for DataResource<T>

where T: Clone,

fn clone(&self) -> DataResource<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T> Debug for DataResource<T>

where T: Debug,

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

Formats the value using the given formatter.

impl<T> Default for DataResource<T>

fn default() -> DataResource<T>

Returns the “default value” for a type.

impl<T> Hash for DataResource<T>

where T: Hash,

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<T> PartialEq for DataResource<T>

where T: PartialEq,

fn eq(&self, other: &DataResource<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> Eq for DataResource<T>

where T: Eq,

impl<T> StructuralPartialEq for DataResource<T>