A direct pending() method (like Action) on LocalResource for use outside Suspense/Transition

[nopeNoshishi]

Context

First, thank you for this fantastic framework — I've been happily building with Leptos and really appreciate the work that has gone into it.

Suspense and Transition are great for declaratively handling loading states in the view tree. However, there are cases where you want to react to a LocalResource's loading state outside of those components — for example, disabling a button while a resource is fetching, showing an inline spinner in a specific part of the UI, or driving some side-effecting logic based on whether a fetch is in flight.

Current workaround and its limitations

The only way to detect loading state today is to check whether .get() returns None:

let is_loading = move || resource.get().is_none();

This works for the initial load, but breaks for re-fetches: once a resource has resolved once, .get() returns the previous Some(T) value even while a new fetch is in flight, so is_none() stays false and there is no way to reactively detect that a re-fetch is happening.

What would be helpful

Action already solves this with a pending() method that returns a Memo<bool>:

let action = Action::new(|input: &String| async { /* ... */ });
let is_pending: Memo<bool> = action.pending();

A similar API on LocalResource would make it straightforward to handle loading state anywhere in the component tree, without having to wrap things in <Suspense> or <Transition>:

let resource = LocalResource::new(|| async { fetch_data().await });
let is_loading: Memo<bool> = resource.pending(); // true during initial load and re-fetches

view! {
    <button disabled=move || is_loading.get()>"Submit"</button>
}

Is there an existing way to get this signal that I'm missing?

[gbj]

Personally I'd probably use the set_pending prop on Transition, which takes a callback that will run whenever it's loading. This allows you to provide a visual cue that it's loading the new data, since it doesn't fall back to the fallback.

There isn't a loading signal or similar on LocalResource or on Resource. The primary resource is that when we had them, they made it very easy to shoot yourself in the foot by causing hydration errors when they were used outside Suspense/Transition.

[nopeNoshishi]

Thank you for the clarification! That makes a lot of sense. I hadn't fully realized the potential for hydration errors when using those signals outside of Suspense/Transition.

I'll stick with the set_pending prop on Transition as you suggested. I'm satisfied with this explanation, so I’ll close this discussion. Thanks for your time!