help mapping chrome.tabs.query callback

[ctaggart]

How would I call [chrome.tabs.query] to get back an array of tabs. I'm struggling to write the interop for this.

https://developer.chrome.com/extensions/tabs#method-query
http://definitelytyped.org/docs/chrome--chrome/interfaces/chrome.tabs.tab.html

I created a module named chrome_tabs.rs and it currently has:

use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub struct QueryInfo {
    pub active: Option<bool>
}

#[wasm_bindgen]
pub struct Tab {
    pub active: bool,
    pub id: u32,
}

#[wasm_bindgen(module = "chrome.tabs")]
extern "C" {
    pub fn query(query_info: QueryInfo, callback: &Fn([&Tab]));
}

Errors with:

error[E0277]: the trait bound `&dyn for<'r> std::ops::Fn([&'r chrome_tabs::Tab]): wasm_bindgen::convert::traits::IntoWasmAbi` is not satisfied
  --> src/chrome_tabs.rs:19:1
   |
19 | #[wasm_bindgen(module = "chrome.tabs")]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `wasm_bindgen::convert::traits::IntoWasmAbi` is not implemented for `&dyn for<'r> std::ops::Fn([&'r chrome_tabs::Tab])`
   |
   = help: the following implementations were found:
             <&'a (dyn for<'r> std::ops::Fn(&'r A) -> R + 'b) as wasm_bindgen::convert::traits::IntoWasmAbi>
             <&'a (dyn std::ops::Fn() -> R + 'b) as wasm_bindgen::convert::traits::IntoWasmAbi>
             <&'a (dyn std::ops::Fn(A) -> R + 'b) as wasm_bindgen::convert::traits::IntoWasmAbi>
             <&'a (dyn std::ops::Fn(A, B) -> R + 'b) as wasm_bindgen::convert::traits::IntoWasmAbi>
           and 6 others

I'm using nightly because I was looking at

wasm-bindgen/tests/wasm/closures.rs

Lines 475 to 491 in 8ba0142

	#[wasm_bindgen]
	pub struct RefFirstArgument {
	contents: u32,
	}
	#[wasm_bindgen_test]
	fn reference_as_first_argument_builds_at_all() {
	#[wasm_bindgen]
	extern "C" {
	fn ref_first_arg1(a: &Fn(&JsValue));
	fn ref_first_arg2(a: &mut FnMut(&JsValue));
	fn ref_first_arg3(a: &Closure<Fn(&JsValue)>);
	fn ref_first_arg4(a: &Closure<FnMut(&JsValue)>);
	fn ref_first_custom1(a: &Fn(&RefFirstArgument));
	fn ref_first_custom2(a: &mut FnMut(&RefFirstArgument));
	fn ref_first_custom3(a: &Closure<Fn(&RefFirstArgument)>);
	fn ref_first_custom4(a: &Closure<FnMut(&RefFirstArgument)>);

trying to find the answer.

wasm-bindgen = { version = "0.2.55", features = ["serde-serialize","nightly"]  }

If I do not make Tab a reference, then I get this error:

error[E0277]: the trait bound `[chrome_tabs::Tab]: wasm_bindgen::convert::traits::FromWasmAbi` is not satisfied
  --> src/chrome_tabs.rs:29:41
   |
29 |     pub fn query(query_info: QueryInfo, callback: &Fn([Tab]));
   |                                         ^^^^^^^^ the trait `wasm_bindgen::convert::traits::FromWasmAbi` is not implemented for `[chrome_tabs::Tab]`
   |
   = note: required because of the requirements on the impl of `wasm_bindgen::convert::traits::IntoWasmAbi` for `&dyn std::ops::Fn([chrome_tabs::Tab])`

[Pauan]

This happens because we don't currently support Vec (or slices) for arbitrary types. So you'll have to use js_sys::Array instead, like this:

pub fn query(query_info: &QueryInfo, callback: &dyn Fn(&js_sys::Array));

Then after this PR is accepted, you'll be able to use to_vec to convert the Array into a Vec (or iter to convert the Array into a Rust Iterator).

[ctaggart]

Thanks! I reread https://rustwasm.github.io/docs/wasm-bindgen/reference/arbitrary-data-with-serde.html and it looks like I can go to and from a JsValue using serde_wasm_bindgen, such as serde_wasm_bindgen::to_value(query_info).unwrap(). I ran into bug #1911 when I tried:

use serde::{Serialize, Deserialize};
use wasm_bindgen::prelude::*;

#[derive(Serialize, Debug)]
pub struct QueryInfo {
    pub active: Option<bool>
}

#[derive(Deserialize, Debug)]
pub struct Tab {
    pub active: bool,
    pub id: u32,
}

#[wasm_bindgen]
extern "C" {
    #[wasm_bindgen(js_namespace = "chrome.tabs")]
    pub fn query(query_info: &JsValue, callback: &dyn Fn(JsValue));
}

[ctaggart]

It took me a while to figure out the lifetimes with the closures, but I'm happy with the result. Great job so far on this library!

Usage

                chrome_tabs::query(&chrome_tabs::QueryInfo{active: None}, &|tabs: Vec<Tab>| 
                    web_sys::console::log_1(&format!("tabs: {:#?}", tabs).into()));

chrome_tabs.rs implementation

use serde::{Serialize, Deserialize};
use wasm_bindgen::prelude::*;

#[derive(Serialize, Debug)]
pub struct QueryInfo {
    pub active: Option<bool>
}

#[derive(Deserialize, Debug)]
pub struct Tab {
    pub active: bool,
    pub id: u32,
}

#[wasm_bindgen]
extern "C" {
    type Tabs;

    #[wasm_bindgen(method)]
    fn query(this: &Tabs, query_info: &JsValue, callback: JsValue);
}

#[wasm_bindgen]
extern "C" {
    #[wasm_bindgen(js_namespace = chrome)]
    static tabs: Tabs;
}

pub fn query(query_info: &QueryInfo, callback: &'static dyn Fn(Vec<Tab>)){
    tabs.query(&serde_wasm_bindgen::to_value(query_info).unwrap(), Closure::once_into_js(move |v: JsValue| 
        callback(serde_wasm_bindgen::from_value(v).unwrap())   
    ));
}

I'm deferring the error handling until later. #1742 looks like a good idea. There is too many unwrap calls above.