feature-gate the form redirect stuff, and clear old errors from query

leptos/Cargo.toml

@@ -20,7 +20,7 @@ typed-builder = "0.18"
 typed-builder-macro = "0.18"
 serde = { version = "1", optional = true }
 serde_json = { version = "1", optional = true }
-server_fn = { workspace = true, features = ["browser", "url", "cbor"] }
+server_fn = { workspace = true, features = ["form-redirects", "browser", "url", "cbor"] }
 web-sys = { version = "0.3.63", features = [
   "ShadowRoot",
   "ShadowRootInit",

server_fn/Cargo.toml

@@ -68,6 +68,7 @@ url = "2"
 
 [features]
 default = [ "json", "cbor"]
+form-redirects = []
 actix = ["ssr", "dep:actix-web", "dep:send_wrapper"]
 axum = [
   "ssr", 

server_fn/src/error.rs

@@ -408,7 +408,7 @@ impl<CustErr> From<ServerFnError<CustErr>> for ServerFnErrorErr<CustErr> {
 /// found at a particular path.
 ///
 /// This can be used to pass an error from the server back to the client
-/// without JavaScript/WASM supported, by encoding it in the URL as a qurey string.
+/// without JavaScript/WASM supported, by encoding it in the URL as a query string.
 /// This is useful for progressive enhancement.
 #[derive(Debug)]
 pub struct ServerFnUrlError<CustErr> {
@@ -450,6 +450,29 @@ impl<CustErr> ServerFnUrlError<CustErr> {
             );
         Ok(url)
     }
+
+    /// Replaces any ServerFnUrlError info from the URL in the given string
+    /// with the serialized success value given.
+    pub fn strip_error_info(path: &mut String) {
+        if let Ok(mut url) = Url::parse(&*path) {
+            // NOTE: This is gross, but the Serializer you get from
+            // .query_pairs_mut() isn't an Iterator so you can't just .retain().
+            let pairs_previously = url
+                .query_pairs()
+                .map(|(k, v)| (k.to_string(), v.to_string()))
+                .collect::<Vec<_>>();
+            let mut pairs = url.query_pairs_mut();
+            pairs.clear();
+            for (key, value) in pairs_previously
+                .into_iter()
+                .filter(|(key, _)| key != "__path" && key != "__err")
+            {
+                pairs.append_pair(&key, &value);
+            }
+            drop(pairs);
+            *path = url.to_string();
+        }
+    }
 }
 
 impl<CustErr> From<ServerFnUrlError<CustErr>> for ServerFnError<CustErr> {

server_fn/src/lib.rs

@@ -238,10 +238,13 @@ where
         // Server functions can either be called by a real Client,
         // or directly by an HTML <form>. If they're accessed by a <form>, default to
         // redirecting back to the Referer.
-        let accepts_html = req
-            .accepts()
-            .map(|n| n.contains("text/html"))
-            .unwrap_or(false);
+        let accepts_html = if cfg!(feature = "form-redirects") {
+            req.accepts()
+                .map(|n| n.contains("text/html"))
+                .unwrap_or(false)
+        } else {
+            false
+        };
         let mut referer = req.referer().as_deref().map(ToOwned::to_owned);
 
         async move {
@@ -256,6 +259,7 @@ where
                 });
 
             // if it accepts HTML, we'll redirect to the Referer
+            #[cfg(feature = "form-redirects")]
             if accepts_html {
                 // if it had an error, encode that error in the URL
                 if let Some(err) = err {
@@ -265,6 +269,11 @@ where
                         referer = Some(url.to_string());
                     }
                 }
+                // otherwise, strip error info from referer URL, as that means it's from a previous
+                // call
+                else if let Some(referer) = referer.as_mut() {
+                    ServerFnUrlError::<Self::Error>::strip_error_info(referer)
+                }
 
                 // set the status code and Location header
                 res.redirect(referer.as_deref().unwrap_or("/"));