Provide global HttpClient to use_future

[patrick-dedication]

Hi,

first off, thanks for making Rust web so great.
I'm trying to provide a global HttpClient so I can use it in my http hooks.
I fear my implementation is aweful, because I clone the HttpClient on every render.
How can I improve?

#[allow(non_snake_case)]
pub fn App(cx: Scope) -> Element {
    use_context_provider(cx, || FetchHttpClient::new("http://127.0.0.1:8000"));

    let slides = use_slides(cx);

    cx.render(match slides.value() {
        Some(slides) => rsx! { Slideshow { slides: slides } },
        None => rsx! { div { "Loading slides..." } },
    })
}

pub fn use_slides(cx: &ScopeState) -> &UseFuture<Slides> {
    let http_client: FetchHttpClient = use_context::<FetchHttpClient>(cx).unwrap().clone();
    use_future(cx, (), |_| async move { get_slides(&http_client).await })
}

Thanks in advance!

[ealmloff]

You can use a Lazy static variable to initialize FetchHttpClient:

static CLIENT: once_cell::sync::Lazy = once_cell::sync::Lazy(|| FetchHttpClient::new("http://127.0.0.1:8000"));

#[allow(non_snake_case)]
pub fn App(cx: Scope) -> Element {
    let slides = use_slides(cx);

    cx.render(match slides.value() {
        Some(slides) => rsx! { Slideshow { slides: slides } },
        None => rsx! { div { "Loading slides..." } },
    })
}

pub fn use_slides(cx: &ScopeState) -> &UseFuture<Slides> {
    use_future(cx, (), |_| async move { get_slides(&CLIENT).await })
}

[ealmloff]

The original code you provided is Dioxus' solution to semi-global state, but you can improve the code in several ways: You can wrap the state in a Rc or Arc to make the state cheaply clonable and either use the dependencies to avoid explicitly cloning the state every time or move the consume context into the future code.

#[allow(non_snake_case)]
pub fn App(cx: Scope) -> Element {
    use_context_provider(cx, || Rc::new(FetchHttpClient::new("http://127.0.0.1:8000")));
    let slides = use_slides(cx);

    cx.render(match slides.value() {
        Some(slides) => rsx! { Slideshow { slides: slides } },
        None => rsx! { div { "Loading slides..." } },
    })
}

pub fn use_slides(cx: &ScopeState) -> &UseFuture<Slides> {
    use_future(cx, (), |_| {
        let http_client: Rc<FetchHttpClient> = cx.consume_context().unwrap();
        async move { get_slides(&).await }
    })
}

[patrick-dedication]

Thanks a lot!

[patrick-dedication]

Hi, I finally got around to try the suggestion.
It turns out, I can't use cx.consume_context() inside the FnOnce passed to use_future.
The lifetime of cx must be 'static to do so, is there a way to solve this?
The full code is here in case you need more context: https://github.com/patrick-dedication/rust-web-slideshow

[ealmloff]

The closure is not required to be 'static, but the future is:

Here is a working version like the above example

use std::rc::Rc;

pub fn use_slides(cx: &ScopeState) -> &UseFuture<()> {
    use_future(cx, (), |_| {
        // cloned before it is moved into the 'static async block
        let http_client: Rc<i32> = cx.consume_context().unwrap();
        async move { println!("{}", &http_client) }
    })
}

Here is a similar version that will output the error you received

pub fn use_slides_broken(cx: &ScopeState) -> &UseFuture<()> {
    use_future(cx, (), |_| async move {
        // because this is inside the 'static async block, cx is 'static
        let http_client: Rc<i32> = cx.consume_context().unwrap();
        println!("{}", &http_client)
    })
}

[patrick-dedication]

Thanks again, and thanks for taking the time to explain :)