#wasm #reactive #fetch #caching


Data fetching and caching for sycamore

2 releases

0.1.1 Dec 19, 2022
0.1.0 Dec 18, 2022

#466 in WebAssembly


579 lines


Provides react-query/tanstack-query style hooks for sycamore. I aim to eventually have mostly feature parity, but the project is currently in an MVP (minimum viable product) state. This means the basic functionality works (caching, background fetching, invalidations, mutations, refetching), but most of the configurability and automatic refetching on window events is missing. If you need a specific feature or configuration option, feel free to open an issue or even a PR and I'll know to prioritise it.


To use the library you need to provide it with a QueryClient as a context. This is ideally done in your top level component or index view so your cache is global. If you want to have separate caches for different parts of your app it could make sense to set multiple QueryClients.

use sycamore_query::{QueryClient, ClientOptions};

pub fn App<G: Html>(cx: Scope) -> View<G> {
    provide_context(cx, QueryClient::new(ClientOptions::default()));
    view! { cx, }

Now you can use use_query and use_mutation from any of your components.

use sycamore_query::{QuerySignalExt, QueryData, query::{use_query, Query}};

pub fn Hello<G: Html>(cx: Scope) -> View<G> {
    let name = create_rc_signal("World".to_string());
    let Query { data, status, refetch } = use_query(
        ("hello", name.get()),
        move || api::hello(name.get())

    match data.get_data() {
        QueryData::Loading => view! { cx, p { "Loading..." } },
        QueryData::Ok(message) => view! { cx, p { (message) } },
        QueryData::Err(err) => view! { cx, p { "An error has occured: " } p { (err) } }

This will fetch the data in the background and handle all sorts of things for you: retrying on error (up to 3 times by default), caching, updating when a mutation invalidates the query or another query with the same key fetches the data, etc.

More information

I don't have the time to write an entire book on this library right now, so just check out the react-query docs and the type level docs for Rust-specific details, keeping in mind only a subset of react-query is currently implemented.


~171K SLoC