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Dioxus 0.5.5ReferenceResource

Resource

use_resource lets you run an async closure, and provides you with its result.

For example, we can make an API request (using reqwest) inside use_resource:

src/use_resource.rs
let mut future = use_resource(|| async move {
    reqwest::get("https://dog.ceo/api/breeds/image/random")
        .await
        .unwrap()
        .json::<ApiResponse>()
        .await
});

The code inside use_resource will be submitted to the Dioxus scheduler once the component has rendered.

We can use .read() to get the result of the future. On the first run, since there's no data ready when the component loads, its value will be None. However, once the future is finished, the component will be re-rendered and the value will now be Some(...), containing the return value of the closure.

We can then render that result:

src/use_resource.rs
match &*future.read_unchecked() {
    Some(Ok(response)) => rsx! {
        button { onclick: move |_| future.restart(), "Click to fetch another doggo" }
        div {
            img {
                max_width: "500px",
                max_height: "500px",
                src: "{response.image_url}",
            }
        }
    },
    Some(Err(_)) => rsx! {
        div { "Loading dogs failed" }
    },
    None => rsx! {
        div { "Loading dogs..." }
    },
}
Loading dogs...

Restarting the Future

The Resource handle provides a restart method. It can be used to execute the future again, producing a new value.

Dependencies

Often, you will need to run the future again every time some value (e.g. a state) changes. Rather than calling restart manually, you can read a signal inside of the future. It will automatically re-run the future when any of the states you read inside the future change. Example:

src/use_resource.rs
let future = use_resource(move || async move {
    reqwest::get(format!("https://dog.ceo/api/breed/{breed}/images/random"))
        .await
        .unwrap()
        .json::<ApiResponse>()
        .await
});

// You can also add non-reactive state to the resource hook with the use_reactive method
let non_reactive_state = "poodle";
use_resource(use_reactive!(|(non_reactive_state,)| async move {
    reqwest::get(format!(
        "https://dog.ceo/api/breed/{non_reactive_state}/images/random"
    ))
    .await
    .unwrap()
    .json::<ApiResponse>()
    .await
}));
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