Add examples of canceling in-flight requests (issue #32) and filter against empty IDs to avoid extra requests (issue #123)

examples/hackernews/Cargo.toml

@@ -26,6 +26,7 @@ serde_json = "1"
 gloo-net = { version = "0.2", features = ["http"] }
 reqwest = { version = "0.11", features = ["json"] }
 # openssl = { version = "0.10", features = ["v110"] }
+web-sys = { version = "0.3", features = ["AbortController", "AbortSignal"] }
 
 [features]
 default = ["csr"]

examples/hackernews/src/api.rs

@@ -1,4 +1,4 @@
-use leptos::Serializable;
+use leptos::{on_cleanup, Scope, Serializable};
 use serde::{Deserialize, Serialize};
 
 pub fn story(path: &str) -> String {
@@ -10,11 +10,15 @@ pub fn user(path: &str) -> String {
 }
 
 #[cfg(not(feature = "ssr"))]
-pub async fn fetch_api<T>(path: &str) -> Option<T>
+pub async fn fetch_api<T>(cx: Scope, path: &str) -> Option<T>
 where
     T: Serializable,
 {
+    let abort_controller = web_sys::AbortController::new().ok();
+    let abort_signal = abort_controller.as_ref().map(|a| a.signal());
+
     let json = gloo_net::http::Request::get(path)
+        .abort_signal(abort_signal.as_ref())
         .send()
         .await
         .map_err(|e| log::error!("{e}"))
@@ -22,11 +26,19 @@ where
         .text()
         .await
         .ok()?;
+
+    // abort in-flight requests if the Scope is disposed
+    // i.e., if we've navigated away from this page
+    on_cleanup(cx, move || {
+        if let Some(abort_controller) = abort_controller {
+            abort_controller.abort()
+        }
+    });
     T::from_json(&json).ok()
 }
 
 #[cfg(feature = "ssr")]
-pub async fn fetch_api<T>(path: &str) -> Option<T>
+pub async fn fetch_api<T>(cx: Scope, path: &str) -> Option<T>
 where
     T: Serializable,
 {

examples/hackernews/src/routes/stories.rs

@@ -32,7 +32,7 @@ pub fn Stories(cx: Scope) -> Element {
         move || (page(), story_type()),
         move |(page, story_type)| async move {
             let path = format!("{}?page={}", category(&story_type), page);
-            api::fetch_api::<Vec<api::Story>>(&api::story(&path)).await
+            api::fetch_api::<Vec<api::Story>>(cx, &api::story(&path)).await
         },
     );
 

examples/hackernews/src/routes/story.rs

@@ -8,7 +8,13 @@ pub fn Story(cx: Scope) -> Element {
     let story = create_resource(
         cx,
         move || params().get("id").cloned().unwrap_or_default(),
-        move |id| async move { api::fetch_api::<api::Story>(&api::story(&format!("item/{id}"))).await },
+        move |id| async move {
+            if id.is_empty() {
+                None
+            } else {
+                api::fetch_api::<api::Story>(cx, &api::story(&format!("item/{id}"))).await
+            }
+        },
     );
 
     view! { cx,

examples/hackernews/src/routes/users.rs

@@ -8,7 +8,13 @@ pub fn User(cx: Scope) -> Element {
     let user = create_resource(
         cx,
         move || params().get("id").cloned().unwrap_or_default(),
-        move |id| async move { api::fetch_api::<User>(&api::user(&id)).await },
+        move |id| async move {
+            if id.is_empty() {
+                None
+            } else {
+                api::fetch_api::<User>(cx, &api::user(&id)).await
+            }
+        },
     );
     view! { cx,
         <div class="user-view">