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use crate::{ServerFn, ServerFnError};
use leptos_reactive::{
create_rw_signal, signal_prelude::*, spawn_local, store_value, ReadSignal,
RwSignal, Scope, StoredValue,
};
use std::{future::Future, pin::Pin, rc::Rc};
/// An action synchronizes an imperative `async` call to the synchronous reactive system.
///
/// If you’re trying to load data by running an `async` function reactively, you probably
/// want to use a [Resource](leptos_reactive::Resource) instead. If you’re trying to occasionally
/// run an `async` function in response to something like a user clicking a button, you're in the right place.
///
/// ```rust
/// # use leptos::*;
/// # run_scope(create_runtime(), |cx| {
/// async fn send_new_todo_to_api(task: String) -> usize {
/// // do something...
/// // return a task id
/// 42
/// }
/// let save_data = create_action(cx, |task: &String| {
/// // `task` is given as `&String` because its value is available in `input`
/// send_new_todo_to_api(task.clone())
/// });
///
/// // the argument currently running
/// let input = save_data.input();
/// // the most recent returned result
/// let result_of_call = save_data.value();
/// // whether the call is pending
/// let pending = save_data.pending();
/// // how many times the action has run
/// // useful for reactively updating something else in response to a `dispatch` and response
/// let version = save_data.version();
///
/// // before we do anything
/// assert_eq!(input(), None); // no argument yet
/// assert_eq!(pending(), false); // isn't pending a response
/// assert_eq!(result_of_call(), None); // there's no "last value"
/// assert_eq!(version(), 0);
/// # if false {
/// // dispatch the action
/// save_data.dispatch("My todo".to_string());
///
/// // when we're making the call
/// // assert_eq!(input(), Some("My todo".to_string()));
/// // assert_eq!(pending(), true); // is pending
/// // assert_eq!(result_of_call(), None); // has not yet gotten a response
///
/// // after call has resolved
/// assert_eq!(input(), None); // input clears out after resolved
/// assert_eq!(pending(), false); // no longer pending
/// assert_eq!(result_of_call(), Some(42));
/// assert_eq!(version(), 1);
/// # }
/// # });
/// ```
///
/// 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 [Action::input] as well.
///
/// ```rust
/// # use leptos::*;
/// # run_scope(create_runtime(), |cx| {
/// // if there's a single argument, just use that
/// let action1 = create_action(cx, |input: &String| {
/// let input = input.clone();
/// async move { todo!() }
/// });
///
/// // if there are no arguments, use the unit type `()`
/// let action2 = create_action(cx, |input: &()| async { todo!() });
///
/// // if there are multiple arguments, use a tuple
/// let action3 =
/// create_action(cx, |input: &(usize, String)| async { todo!() });
/// # });
/// ```
pub struct Action<I, O>(StoredValue<ActionState<I, O>>)
where
I: 'static,
O: 'static;
impl<I, O> Action<I, O>
where
I: 'static,
O: 'static,
{
/// Calls the `async` function with a reference to the input type as its argument.
pub fn dispatch(&self, input: I) {
self.0.with_value(|a| a.dispatch(input))
}
/// Whether the action has been dispatched and is currently waiting for its future to be resolved.
pub fn pending(&self) -> ReadSignal<bool> {
self.0.with_value(|a| a.pending.read_only())
}
/// Updates whether the action is currently pending.
pub fn set_pending(&self, pending: bool) {
self.0.try_with_value(|a| a.pending.set(pending));
}
/// The URL associated with the action (typically as part of a server function.)
/// This enables integration with the `ActionForm` component in `leptos_router`.
pub fn url(&self) -> Option<String> {
self.0.with_value(|a| a.url.as_ref().cloned())
}
/// Associates the URL of the given server function with this action.
/// This enables integration with the `ActionForm` component in `leptos_router`.
pub fn using_server_fn<T: ServerFn>(self) -> Self {
let prefix = T::prefix();
self.0.update_value(|state| {
state.url = if prefix.is_empty() {
Some(T::url().to_string())
} else {
Some(prefix.to_string() + "/" + T::url())
};
});
self
}
/// How many times the action has successfully resolved.
pub fn version(&self) -> RwSignal<usize> {
self.0.with_value(|a| a.version)
}
/// The current argument that was dispatched to the `async` function.
/// `Some` while we are waiting for it to resolve, `None` if it has resolved.
pub fn input(&self) -> RwSignal<Option<I>> {
self.0.with_value(|a| a.input)
}
/// The most recent return value of the `async` function.
pub fn value(&self) -> RwSignal<Option<O>> {
self.0.with_value(|a| a.value)
}
}
impl<I, O> Clone for Action<I, O>
where
I: 'static,
O: 'static,
{
fn clone(&self) -> Self {
Self(self.0)
}
}
impl<I, O> Copy for Action<I, O>
where
I: 'static,
O: 'static,
{
}
struct ActionState<I, O>
where
I: 'static,
O: 'static,
{
/// How many times the action has successfully resolved.
pub version: RwSignal<usize>,
/// The current argument that was dispatched to the `async` function.
/// `Some` while we are waiting for it to resolve, `None` if it has resolved.
pub input: RwSignal<Option<I>>,
/// The most recent return value of the `async` function.
pub value: RwSignal<Option<O>>,
pending: RwSignal<bool>,
url: Option<String>,
#[allow(clippy::complexity)]
action_fn: Rc<dyn Fn(&I) -> Pin<Box<dyn Future<Output = O>>>>,
}
impl<I, O> ActionState<I, O>
where
I: 'static,
O: 'static,
{
/// Calls the `async` function with a reference to the input type as its argument.
pub fn dispatch(&self, input: I) {
let fut = (self.action_fn)(&input);
self.input.set(Some(input));
let input = self.input;
let version = self.version;
let pending = self.pending;
let value = self.value;
pending.set(true);
spawn_local(async move {
let new_value = fut.await;
value.set(Some(new_value));
input.set(None);
pending.set(false);
version.update(|n| *n += 1);
})
}
}
/// Creates an [Action] to synchronize an imperative `async` call to the synchronous reactive system.
///
/// If you’re trying to load data by running an `async` function reactively, you probably
/// want to use a [create_resource](leptos_reactive::create_resource) instead. If you’re trying
/// to occasionally run an `async` function in response to something like a user clicking a button,
/// you're in the right place.
///
/// ```rust
/// # use leptos::*;
/// # run_scope(create_runtime(), |cx| {
/// async fn send_new_todo_to_api(task: String) -> usize {
/// // do something...
/// // return a task id
/// 42
/// }
/// let save_data = create_action(cx, |task: &String| {
/// // `task` is given as `&String` because its value is available in `input`
/// send_new_todo_to_api(task.clone())
/// });
///
/// // the argument currently running
/// let input = save_data.input();
/// // the most recent returned result
/// let result_of_call = save_data.value();
/// // whether the call is pending
/// let pending = save_data.pending();
/// // how many times the action has run
/// // useful for reactively updating something else in response to a `dispatch` and response
/// let version = save_data.version();
///
/// // before we do anything
/// assert_eq!(input(), None); // no argument yet
/// assert_eq!(pending(), false); // isn't pending a response
/// assert_eq!(result_of_call(), None); // there's no "last value"
/// assert_eq!(version(), 0);
/// # if false {
/// // dispatch the action
/// save_data.dispatch("My todo".to_string());
///
/// // when we're making the call
/// // assert_eq!(input(), Some("My todo".to_string()));
/// // assert_eq!(pending(), true); // is pending
/// // assert_eq!(result_of_call(), None); // has not yet gotten a response
///
/// // after call has resolved
/// assert_eq!(input(), None); // input clears out after resolved
/// assert_eq!(pending(), false); // no longer pending
/// assert_eq!(result_of_call(), Some(42));
/// assert_eq!(version(), 1);
/// # }
/// # });
/// ```
///
/// 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 [Action::input] as well.
///
/// ```rust
/// # use leptos::*;
/// # run_scope(create_runtime(), |cx| {
/// // if there's a single argument, just use that
/// let action1 = create_action(cx, |input: &String| {
/// let input = input.clone();
/// async move { todo!() }
/// });
///
/// // if there are no arguments, use the unit type `()`
/// let action2 = create_action(cx, |input: &()| async { todo!() });
///
/// // if there are multiple arguments, use a tuple
/// let action3 =
/// create_action(cx, |input: &(usize, String)| async { todo!() });
/// # });
/// ```
pub fn create_action<I, O, F, Fu>(cx: Scope, action_fn: F) -> Action<I, O>
where
I: 'static,
O: 'static,
F: Fn(&I) -> Fu + 'static,
Fu: Future<Output = O> + 'static,
{
let version = create_rw_signal(cx, 0);
let input = create_rw_signal(cx, None);
let value = create_rw_signal(cx, None);
let pending = create_rw_signal(cx, false);
let action_fn = Rc::new(move |input: &I| {
let fut = action_fn(input);
Box::pin(fut) as Pin<Box<dyn Future<Output = O>>>
});
Action(store_value(
cx,
ActionState {
version,
url: None,
input,
value,
pending,
action_fn,
},
))
}
/// Creates an [Action] that can be used to call a server function.
///
/// ```rust
/// # use leptos::*;
///
/// #[server(MyServerFn)]
/// async fn my_server_fn() -> Result<(), ServerFnError> {
/// todo!()
/// }
///
/// # run_scope(create_runtime(), |cx| {
/// let my_server_action = create_server_action::<MyServerFn>(cx);
/// # });
/// ```
pub fn create_server_action<S>(
cx: Scope,
) -> Action<S, Result<S::Output, ServerFnError>>
where
S: Clone + ServerFn,
{
#[cfg(feature = "ssr")]
let c = move |args: &S| S::call_fn(args.clone(), cx);
#[cfg(not(feature = "ssr"))]
let c = move |args: &S| S::call_fn_client(args.clone(), cx);
create_action(cx, c).using_server_fn::<S>()
}