Struct ArcMultiAction 

pub struct ArcMultiAction<I, O> { /* private fields */ }

An action that synchronizes multiple imperative async calls to the reactive system, tracking the progress of each one.

Where an Action fires a single call, a MultiAction allows you to keep track of multiple in-flight actions.

If you’re trying to load data by running an async function reactively, you probably want to use an AsyncDerived instead. If you’re trying to occasionally run an async function in response to something like a user adding a task to a todo list, you’re in the right place.

The arena-allocated, Copy version of an ArcMultiAction is a MultiAction.

async fn send_new_todo_to_api(task: String) -> usize {
  // do something...
  // return a task id
  42
}
let add_todo = ArcMultiAction::new(|task: &String| {
  // `task` is given as `&String` because its value is available in `input`
  send_new_todo_to_api(task.clone())
});

add_todo.dispatch("Buy milk".to_string());
add_todo.dispatch("???".to_string());
add_todo.dispatch("Profit!!!".to_string());

let submissions = add_todo.submissions();
assert_eq!(submissions.with(Vec::len), 3);

Implementations

impl<I, O> ArcMultiAction<I, O>

pub fn new<Fut>( action_fn: impl Fn(&I) -> Fut + Send + Sync + 'static, ) -> ArcMultiAction<I, O>

where Fut: Future<Output = O> + Send + 'static,

Creates a new multi-action.

The input to the async function should always be a single value, but it can be of any type. The argument is always passed by reference to the function, because it is stored in Submission::input as well.

// if there's a single argument, just use that
let action1 = ArcMultiAction::new(|input: &String| {
    let input = input.clone();
    async move { todo!() }
});

// if there are no arguments, use the unit type `()`
let action2 = ArcMultiAction::new(|input: &()| async { todo!() });

// if there are multiple arguments, use a tuple
let action3 =
    ArcMultiAction::new(|input: &(usize, String)| async { todo!() });

impl<I, O> ArcMultiAction<I, O>

where I: Send + Sync + 'static, O: Send + Sync + 'static,

pub fn dispatch(&self, input: I)

Calls the async function with a reference to the input type as its argument.

This can be called any number of times: each submission will be dispatched, running concurrently, and its status can be checked via the submissions() signal.

async fn send_new_todo_to_api(task: String) -> usize {
  // do something...
  // return a task id
  42
}
let add_todo = ArcMultiAction::new(|task: &String| {
  // `task` is given as `&String` because its value is available in `input`
  send_new_todo_to_api(task.clone())
});

let submissions = add_todo.submissions();
let pending_submissions = {
    let submissions = submissions.clone();
    move || {
        submissions.with(|subs| subs.iter().filter(|sub| sub.pending().get()).count())
    }
};

add_todo.dispatch("Buy milk".to_string());
assert_eq!(submissions.with(Vec::len), 1);
assert_eq!(pending_submissions(), 1);

add_todo.dispatch("???".to_string());
add_todo.dispatch("Profit!!!".to_string());

assert_eq!(submissions.with(Vec::len), 3);
assert_eq!(pending_submissions(), 3);

// when submissions resolve, they are not removed from the set
// however, their `pending` signal is now `false`, and this can be used to filter them
assert_eq!(submissions.with(Vec::len), 3);
assert_eq!(pending_submissions(), 0);

pub fn dispatch_sync(&self, value: O)

Synchronously adds a submission with the given value.

This takes the output value, rather than the input, because it is adding a result, not an input.

This can be useful for use cases like handling errors, where the error can already be known on the client side.

async fn send_new_todo_to_api(task: String) -> usize {
  // do something...
  // return a task id
  42
}
let add_todo = ArcMultiAction::new(|task: &String| {
  // `task` is given as `&String` because its value is available in `input`
  send_new_todo_to_api(task.clone())
});

let submissions = add_todo.submissions();
let pending_submissions = {
    let submissions = submissions.clone();
    move || {
        submissions.with(|subs| subs.iter().filter(|sub| sub.pending().get()).count())
    }
};

add_todo.dispatch("Buy milk".to_string());
assert_eq!(submissions.with(Vec::len), 1);
assert_eq!(pending_submissions(), 1);

add_todo.dispatch_sync(42);

assert_eq!(submissions.with(Vec::len), 2);
assert_eq!(pending_submissions(), 1);

impl<I, O> ArcMultiAction<I, O>

pub fn submissions(&self) -> ArcReadSignal<Vec<ArcSubmission<I, O>>>

The set of all submissions to this multi-action.

async fn send_new_todo_to_api(task: String) -> usize {
  // do something...
  // return a task id
  42
}
let add_todo = ArcMultiAction::new(|task: &String| {
  // `task` is given as `&String` because its value is available in `input`
  send_new_todo_to_api(task.clone())
});

let submissions = add_todo.submissions();

add_todo.dispatch("Buy milk".to_string());
add_todo.dispatch("???".to_string());
add_todo.dispatch("Profit!!!".to_string());

assert_eq!(submissions.with(Vec::len), 3);

pub fn version(&self) -> ArcRwSignal<usize>

How many times an action has successfully resolved.

async fn send_new_todo_to_api(task: String) -> usize {
  // do something...
  // return a task id
  42
}
let add_todo = ArcMultiAction::new(|task: &String| {
  // `task` is given as `&String` because its value is available in `input`
  send_new_todo_to_api(task.clone())
});

let version = add_todo.version();

add_todo.dispatch("Buy milk".to_string());
add_todo.dispatch("???".to_string());
add_todo.dispatch("Profit!!!".to_string());

assert_eq!(version.get(), 0);

// when they've all resolved
assert_eq!(version.get(), 3);

Trait Implementations

impl<I, O> Clone for ArcMultiAction<I, O>

where I: 'static, O: 'static,

fn clone(&self) -> ArcMultiAction<I, O>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<I, O> Debug for ArcMultiAction<I, O>

where I: 'static, O: 'static,

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

Formats the value using the given formatter.