use_reducer no longer re-renders on identity dispatches#use_reducer now skips re-rendering when the reducer returns the same Rc (checked by pointer equality). Previously, every dispatch triggered a re-render regardless.
If your reducer has a code path that returns self unchanged and you relied on that causing a re-render, replace it with use_force_update:
pub enum Action {
Increment,
ForceRefresh,
}
struct State {
count: u32,
}
impl Reducible for State {
type Action = Action;
fn reduce(self: Rc<Self>, action: Self::Action) -> Rc<Self> {
match action {
Action::Increment => Rc::new(Self {
count: self.count + 1,
}),
// This no longer triggers a re-render in 0.23!
Action::ForceRefresh => self,
}
}
}
#[component]
pub fn App() -> Html {
use_effect(|| {
tracing::info!("This cursed component does some effects on render");
});
let state = use_reducer(|| State { count: 0 });
html! {
<div>
<p>{ state.count }</p>
<button onclick={
let state = state.clone();
move |_| state.dispatch(Action::Increment)
}>
{ "+1" }
</button>
<button onclick={move |_| state.dispatch(Action::ForceRefresh)}>
{ "Refresh" }
</button>
</div>
}
}
pub enum Action {
Increment,
}
struct State {
count: u32,
}
impl Reducible for State {
type Action = Action;
fn reduce(self: Rc<Self>, action: Self::Action) -> Rc<Self> {
match action {
Action::Increment => Rc::new(Self {
count: self.count + 1,
}),
}
}
}
#[component]
pub fn App() -> Html {
use_effect(|| {
tracing::info!("This cursed component does some effects on render");
});
let state = use_reducer(|| State { count: 0 });
let trigger = use_force_update();
html! {
<div>
<p>{ state.count }</p>
<button onclick={move |_| state.dispatch(Action::Increment)}>{ "+1" }</button>
<button onclick={move |_| trigger.force_update()}>{ "Refresh" }</button>
</div>
}
}