Query parameters

Read URL search params from FlowRequest in pages, loaders, and submits.

Single parameter

pub fn page(req: FlowRequest) -> View {
    let q = req.query_param("q").unwrap_or("");
    view! {
        <>
            <h1>"Search"</h1>
            <p>"Query: " {q.to_string()}</p>
        </>
    }
}

In loaders

#[load]
async fn search_results(req: &FlowRequest) -> Result<Vec<Item>, LoaderError> {
    let q = req.query_param("q").unwrap_or("");
    if q.is_empty() {
        return Ok(vec![]);
    }
    db::search(q).await.map_err(|_| LoaderError::new(500, "search failed"))
}

Forms that preserve query state

<form method="get" action="/docs/search">
    <input type="search" name="q" placeholder="Search docs…" />
</form>

Reload loaders without full page refresh (SPA)

Changing only client state does not re-run #[load]. For booking flows (pick a date, refresh time slots), navigate to the same path with new query params so the server renders again:

on:change={js! {
    const input = event.target;
    if (!(input instanceof HTMLInputElement) || !input.value) return;
    await __resuma.navigate(__resuma.buildUrl("/reservar", {
        fecha: input.value,
        servicio: new URLSearchParams(location.search).get("servicio"),
    }));
}}

Use event.target, not event.currentTarget. In async handlers, currentTarget is often null.

Rust helpers

loader_refresh_input(
    "/reservar",
    "fecha",
    &date,
    &["servicio"],   // query keys to preserve
    "date",
    vec![("required".into(), AttrValue::Bool(true))],
)

query_nav_link("/servicios", &[("cat", "corte")], "active", "", vec![...]);

build_query_href("/book", &[("fecha", "2026-06-02")]);

See template flow-booking (resuma new my-app --template flow-booking) and PWA and public/ for a full sample.

Flash after redirect

Combine PRG redirects with a query flag:

#[submit]
async fn create(form: ItemForm, _req: &FlowRequest) -> Result<Redirect, SubmitError> {
    db::insert(&form).await.map_err(|_| SubmitError::new("Failed"))?;
    Ok(redirect("/items?created=1"))
}

pub fn page(req: FlowRequest) -> View {
    let created = req.query_param("created") == Some("1");
    view! {
        <>
            {if created {
                view! { <p class="toast">"Item created!"</p> }
            } else {
                View::empty()
            }}
        </>
    }
}

Parsing notes

• Values are percent-decoded by the Flow request layer.
• Duplicate keys: last value wins (same as typical query parsers).
• Use path params (req.param('id')) for /users/:id segments.