Leptos Files

This release includes WASM code-splitting/lazy-loading support, in tandem with the latest cargo-leptos release.

You can use the lazy_routes example to understand what this means!

Essentially, though, there are two patterns: 1. Use the #[lazy] macro to make any given function lazy 2. Use the #[lazy_route] to designate a route with a lazy-loaded view, which is loaded concurrently with the route's data

#[lazy] converts a (sync or async) function into a lazy-loaded async function

:::rust
#[lazy]
fn deserialize_comments(data: &str) -> Vec<Comment> {
    serde_json::from_str(data).unwrap()
}

#[lazy_route] lets you split routes into a "data" half and a "view" half, which will be concurrently loaded by the router. This works with nested routing: so if you have ViewD and ViewE, then the router will concurrently load D's data, D's (lazy) view, E's data, and E's (lazy) view, before navigating to the page.

:::rust
struct ViewD {
    data: Resource<Result<Vec<i32>, ServerFnError>>,
}

#[lazy_route]
impl LazyRoute for ViewD {
    fn data() -> Self {
        Self {
            data: Resource::new(|| (), |_| d_data()),
        }
    }

    fn view(this: Self) -> AnyView {
        let items = move || {
            Suspend::new(async move {
                this.data
                    .await
                    .unwrap_or_default()
                    .into_iter()
                    .map(|item| view! { <li>{item}</li> })
                    .collect::<Vec<_>>()
            })
        };
        view! {
            <p id="page">"View D"</p>
            <hr/>
            <Suspense fallback=|| view! { <p id="loading">"Loading..."</p> }>
                <ul>{items}</ul>
            </Suspense>
            <Outlet/>
        }
        .into_any()
    }
}

#[server]
async fn d_data() -> Result<Vec<i32>, ServerFnError> {
    tokio::time::sleep(std::time::Duration::from_millis(250)).await;
    Ok(vec![1, 1, 2, 3, 5, 8, 13])
}

Our whole July stream was dedicated to the topic, if you want more in depth discussion.

What's Changed

• Preparing to publish oco_ref 0.2.1 by @martinfrances107 in https://github.com/leptos-rs/leptos/pull/4168
• feat: wasm-splitting library support for future cargo-leptos integration by @gbj in https://github.com/leptos-rs/leptos/pull/3988

Full Changelog: https://github.com/leptos-rs/leptos/compare/v0.8.4...v0.8.5