allow returning values from use_eval

examples/eval.rs

@@ -1,4 +1,5 @@
 use dioxus::prelude::*;
+use dioxus_desktop::EvalResult;
 
 fn main() {
     dioxus_desktop::launch(app);
@@ -7,6 +8,15 @@ fn main() {
 fn app(cx: Scope) -> Element {
     let script = use_state(&cx, String::new);
     let eval = dioxus_desktop::use_eval(&cx);
+    let future: &UseRef<Option<EvalResult>> = use_ref(&cx, || None);
+    if future.read().is_some() {
+        let future_clone = future.clone();
+        cx.spawn(async move {
+            if let Some(fut) = future_clone.with_mut(|o| o.take()) {
+                println!("{:?}", fut.await)
+            }
+        });
+    }
 
     cx.render(rsx! {
         div {
@@ -16,7 +26,10 @@ fn app(cx: Scope) -> Element {
                 oninput: move |e| script.set(e.value.clone()),
             }
             button {
-                onclick: move |_| eval(script),
+                onclick: move |_| {
+                    let fut = eval(script);
+                    future.set(Some(fut));
+                },
                 "Execute"
             }
         }

packages/desktop/src/controller.rs

@@ -3,6 +3,7 @@ use crate::desktop_context::{DesktopContext, UserWindowEvent};
 use dioxus_core::*;
 #[cfg(target_os = "ios")]
 use objc::runtime::Object;
+use serde_json::Value;
 use std::{
     collections::HashMap,
     sync::Arc,
@@ -17,6 +18,7 @@ use wry::{
 pub(super) struct DesktopController {
     pub(super) webviews: HashMap<WindowId, WebView>,
     pub(super) sender: futures_channel::mpsc::UnboundedSender<SchedulerMsg>,
+    pub(super) eval_sender: tokio::sync::mpsc::UnboundedSender<Value>,
     pub(super) pending_edits: Arc<Mutex<Vec<String>>>,
     pub(super) quit_app_on_close: bool,
     pub(super) is_ready: Arc<AtomicBool>,
@@ -38,6 +40,7 @@ impl DesktopController {
         let pending_edits = edit_queue.clone();
         let return_sender = sender.clone();
         let desktop_context_proxy = proxy.clone();
+        let (eval_sender, eval_reciever) = tokio::sync::mpsc::unbounded_channel::<Value>();
 
         std::thread::spawn(move || {
             // We create the runtime as multithreaded, so you can still "spawn" onto multiple threads
@@ -50,7 +53,7 @@ impl DesktopController {
                 let mut dom =
                     VirtualDom::new_with_props_and_scheduler(root, props, (sender, receiver));
 
-                let window_context = DesktopContext::new(desktop_context_proxy);
+                let window_context = DesktopContext::new(desktop_context_proxy, eval_reciever);
 
                 dom.base_scope().provide_context(window_context);
 
@@ -88,6 +91,7 @@ impl DesktopController {
         Self {
             pending_edits,
             sender: return_sender,
+            eval_sender,
             webviews: HashMap::new(),
             is_ready: Arc::new(AtomicBool::new(false)),
             quit_app_on_close: true,

packages/desktop/src/desktop_context.rs

@@ -1,5 +1,11 @@
 use crate::controller::DesktopController;
 use dioxus_core::ScopeState;
+use serde::de::Error;
+use serde_json::Value;
+use std::future::Future;
+use std::future::IntoFuture;
+use std::pin::Pin;
+use std::rc::Rc;
 use wry::application::event_loop::ControlFlow;
 use wry::application::event_loop::EventLoopProxy;
 #[cfg(target_os = "ios")]
@@ -33,11 +39,18 @@ pub fn use_window(cx: &ScopeState) -> &DesktopContext {
 pub struct DesktopContext {
     /// The wry/tao proxy to the current window
     pub proxy: ProxyType,
+    pub(super) eval_reciever: Rc<tokio::sync::Mutex<tokio::sync::mpsc::UnboundedReceiver<Value>>>,
 }
 
 impl DesktopContext {
-    pub(crate) fn new(proxy: ProxyType) -> Self {
+    pub(crate) fn new(
-        Self { proxy }
+        proxy: ProxyType,
+        eval_reciever: tokio::sync::mpsc::UnboundedReceiver<Value>,
+    ) -> Self {
+        Self {
+            proxy,
+            eval_reciever: Rc::new(tokio::sync::Mutex::new(eval_reciever)),
+        }
     }
 
     /// trigger the drag-window event
@@ -245,7 +258,13 @@ pub(super) fn handler(
         }
 
         Eval(code) => {
-            if let Err(e) = webview.evaluate_script(code.as_str()) {
+            let script = format!(
+                r#"window.ipc.postMessage(JSON.stringify({{"method":"eval_result", params: (function(){{
+                    {}
+                }})()}}));"#,
+                code
+            );
+            if let Err(e) = webview.evaluate_script(&script) {
                 // we can't panic this error.
                 log::warn!("Eval script error: {e}");
             }
@@ -280,10 +299,36 @@ pub(super) fn handler(
 }
 
 /// Get a closure that executes any JavaScript in the WebView context.
-pub fn use_eval<S: std::string::ToString>(cx: &ScopeState) -> &dyn Fn(S) {
+pub fn use_eval<S: std::string::ToString>(cx: &ScopeState) -> &dyn Fn(S) -> EvalResult {
     let desktop = use_window(cx).clone();
+    cx.use_hook(|| {
+        move |script| {
+            desktop.eval(script);
+            let recv = desktop.eval_reciever.clone();
+            EvalResult { reciever: recv }
+        }
+    })
+}
 
-    cx.use_hook(|| move |script| desktop.eval(script))
+/// A future that resolves to the result of a JavaScript evaluation.
+pub struct EvalResult {
+    reciever: Rc<tokio::sync::Mutex<tokio::sync::mpsc::UnboundedReceiver<serde_json::Value>>>,
+}
+
+impl IntoFuture for EvalResult {
+    type Output = Result<serde_json::Value, serde_json::Error>;
+
+    type IntoFuture = Pin<Box<dyn Future<Output = Result<serde_json::Value, serde_json::Error>>>>;
+
+    fn into_future(self) -> Self::IntoFuture {
+        Box::pin(async move {
+            let mut reciever = self.reciever.lock().await;
+            match reciever.recv().await {
+                Some(result) => Ok(result),
+                None => Err(serde_json::Error::custom("No result returned")),
+            }
+        }) as Pin<Box<dyn Future<Output = Result<serde_json::Value, serde_json::Error>>>>
+    }
 }
 
 #[cfg(target_os = "ios")]

packages/desktop/src/lib.rs

@@ -13,7 +13,7 @@ mod hot_reload;
 mod protocol;
 
 use desktop_context::UserWindowEvent;
-pub use desktop_context::{use_eval, use_window, DesktopContext};
+pub use desktop_context::{use_eval, use_window, DesktopContext, EvalResult};
 pub use wry;
 pub use wry::application as tao;
 
@@ -126,7 +126,11 @@ pub fn launch_with_props<P: 'static + Send>(root: Component<P>, props: P, mut cf
                 let window = builder.build(event_loop).unwrap();
                 let window_id = window.id();
 
-                let (is_ready, sender) = (desktop.is_ready.clone(), desktop.sender.clone());
+                let (is_ready, sender, eval_sender) = (
+                    desktop.is_ready.clone(),
+                    desktop.sender.clone(),
+                    desktop.eval_sender.clone(),
+                );
 
                 let proxy = proxy.clone();
 
@@ -143,6 +147,10 @@ pub fn launch_with_props<P: 'static + Send>(root: Component<P>, props: P, mut cf
                     .with_ipc_handler(move |_window: &Window, payload: String| {
                         parse_ipc_message(&payload)
                             .map(|message| match message.method() {
+                                "eval_result" => {
+                                    let result = message.params();
+                                    eval_sender.send(result).unwrap();
+                                }
                                 "user_event" => {
                                     let event = trigger_from_serialized(message.params());
                                     log::trace!("User event: {:?}", event);

packages/web/Cargo.toml

@@ -30,6 +30,7 @@ futures-util = "0.3.19"
 smallstr = "0.2.0"
 futures-channel = "0.3.21"
 serde_json = { version = "1.0" }
+serde = { version = "1.0" }
 
 [dependencies.web-sys]
 version = "0.3.56"

packages/web/src/util.rs

@@ -1,6 +1,10 @@
 //! Utilities specific to websys
 
+use std::str::FromStr;
+
 use dioxus_core::*;
+use serde::de::Error;
+use serde_json::Value;
 
 /// Get a closure that executes any JavaScript in the webpage.
 ///
@@ -15,12 +19,24 @@ use dioxus_core::*;
 ///
 /// The closure will panic if the provided script is not valid JavaScript code
 /// or if it returns an uncaught error.
-pub fn use_eval<S: std::string::ToString>(cx: &ScopeState) -> &dyn Fn(S) {
+pub fn use_eval<S: std::string::ToString>(
+    cx: &ScopeState,
+) -> &dyn Fn(S) -> Result<Value, serde_json::Error> {
     cx.use_hook(|| {
         |script: S| {
-            js_sys::Function::new_no_args(&script.to_string())
+            let body = script.to_string();
-                .call0(&wasm_bindgen::JsValue::NULL)
+            if let Ok(value) =
-                .expect("failed to eval script");
+                js_sys::Function::new_no_args(&body).call0(&wasm_bindgen::JsValue::NULL)
+            {
+                if let Ok(stringified) = js_sys::JSON::stringify(&value) {
+                    let string: String = stringified.into();
+                    Value::from_str(&string)
+                } else {
+                    Err(serde_json::Error::custom("Failed to stringify result"))
+                }
+            } else {
+                Err(serde_json::Error::custom("Failed to execute script"))
+            }
         }
     })
 }