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Implement Into<JsValue>
for Vec
#3630
Conversation
Is there any progress here? This would be a fantastic feature |
Something I was always wondering about in wasm-bindgen is why JsValue conversions can't just reuse the ABI representation instead of adding lots of new intrinsics. For example, it's already possible to implement any such conversions as #[wasm_bindgen]
extern {
#[wasm_bindgen(js_name = Object)] // using Object(x) as just an identity function for `x=>x`
fn convert(values: Vec<u32>) -> JsValue;
} It should be possible to generate similar stubs generically for arbitrary types, without resorting to |
Any updates on this? |
This means that `Vec`s can now be returned from `async` functions. Fixes rustwasm#3155. I had to add a new `VectorIntoJsValue` trait, since similarly to `VectorIntoWasmAbi` the orphan rule won't let us directly implement `From<Vec<T>>` for `JsValue` outside of `wasm-bindgen`.
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I was holding out on merging this until I got around to properly benchmarking whether the current approach or the copy-into-a- |
@Liamolucko thank you so much for implementing this! I'm currently trying it out and can't seem to get it working. I wonder what I'm missing. Here's my cargo:
and my lib
And rust complains with
|
The underlying problem going on there is that you're ending up depending on two different versions of The proper way to switch to a git version of [package]
name = "hui"
version = "0.1.0"
edition = "2021"
[lib]
crate-type = ["cdylib", "rlib"]
[dependencies]
wasm-bindgen = "*"
wasm-bindgen-futures = "*"
[patch.crates-io]
wasm-bindgen = { git = "https://github.com/rustwasm/wasm-bindgen" } As for why you got that error, it's due to a weird interaction with |
Thanks @Liamolucko! Awesome explanation and not so obvious. I wouldn't found that issue without your help. Works great! |
@Liamolucko // this doesn't work
#[wasm_bindgen]
pub async fn test_wait_vec() -> Vec<Data> //the trait `JsObject` is not implemented for `Data`, which is required by `Vec<Data>: wasm_bindgen::describe::WasmDescribe`
{
vec![Data::new()]
}
// This works
#[wasm_bindgen]
pub async fn test_wait() -> Data {
Data::new()
}
#[derive(Serialize, Deserialize, Tsify)]
#[into_wasm_abi]
pub struct Data {
pub time: SystemTime,
pub map: HashMap<Test, InnerData>,
}
impl Into<JsValue> for Data {
fn into(self) -> JsValue {
serde_wasm_bindgen::to_value(&self).unwrap()
}
}
impl VectorIntoJsValue for Data {
fn vector_into_jsvalue(vector: Box<[Data]>) -> JsValue {
wasm_bindgen::__rt::js_value_vector_into_jsvalue(vector)
}
} The error is in the comment. When I implement any combination of the following traits below... impl WasmDescribeVector for Data {
fn describe_vector() {
inform(VECTOR);
Data::describe();
}
}
impl VectorIntoJsValue for Data {
fn vector_into_jsvalue(vector: Box<[Data]>) -> JsValue {
wasm_bindgen::__rt::js_value_vector_into_jsvalue(vector)
}
}
impl VectorIntoWasmAbi for Data {
type Abi = WasmSlice;
fn vector_into_abi(vector: Box<[Self]>) -> WasmSlice {
let jsvaluevec: Box<[JsValue]> = vector
.iter()
.map(|x| serde_wasm_bindgen::to_value(&x).unwrap())
.collect();
JsValue::vector_into_abi(jsvaluevec)
}
} I get a different error: error: import of Thank you for your time! :) |
From a quick glance it looks like this would be related to #3919? |
This means that
Vec
s can now be returned fromasync
functions.Fixes #3155.
I had to add a new
VectorIntoJsValue
trait, since similarly toVectorIntoWasmAbi
the orphan rule won't let us directly implementFrom<Vec<T>>
forJsValue
outside ofwasm-bindgen
.I did some quick benchmarking, and it seems like the copy-into-a-new-
Vec
approach used to returnVec
s from synchronous functions is faster:So it might be a good idea to later change this to use a similar implementation. However I haven't checked if these results are the same in other JS runtimes so take that with a grain of salt.