Importing a js function with an object parameter - Rust / wasm_bindgen

I'm trying to use a JS function from within rust with wasm_bindgen, the function has an object parameter similar to functions like fetch:

#[wasm_bindgen]
extern "C" {
    #[wasm_bindgen]
    fn fetch(resource: &str, config: &JsValue);
}

(just using fetch as an example, I know that there are better ways to use fetch from rust...)

I'm not sure how to model the config object in rust.

I tried using JsValue but it seems that JsValue can only be created from primitive types and not from objects.

I've seen online some suggestions that serde can help here but I couldn't find any concrete examples, and my attempt to get it to work myself were not fruitful either.

Thanks in advance for looking into this!

Solution

It looks like you can either use js_sys::Reflect to access or set arbitrary values, or you can use serde to parse/unparse values

For the first method, this resource explains how to read or write a property on an untyped object: https://rustwasm.github.io/docs/wasm-bindgen/reference/accessing-properties-of-untyped-js-values.html and an example of using this interface can be found in web-sys itself, which defines the RequestInit object which is used when building the config object for fetch(): https://docs.rs/web-sys/0.3.50/src/web_sys/features/gen_RequestInit.rs.html#4

The other way is to use serde. An example of this can be found at https://rustwasm.github.io/docs/wasm-bindgen/examples/fetch.html and a more detailed explanation can be found at https://rustwasm.github.io/docs/wasm-bindgen/reference/arbitrary-data-with-serde.html

After defining the objects to serialize and deserialize, the JsValue::from_serde() and .into_serde() can be used to convert to and from a JsValue