fix: perform server navigation roundtrip only when client side naviga…

…tion is completed (#20187) (#20195)

Fixes #19822

Co-authored-by: Marco Collovati <[email protected]>

flow-server/src/main/resources/com/vaadin/flow/server/frontend/Flow.tsx

@@ -364,7 +364,8 @@ function Flow() {
             let blockingPromise: any;
             roundTrip.current = new Promise<void>((resolve,reject) => blockingPromise = {resolve:resolve,reject:reject});
 
-            // Do not skip server round-trip if navigation originates from a click on a link
+            // Proceed to the blocked location, unless the navigation originates from a click on a link.
+            // In that case continue with function execution and perform a server round-trip
             if (navigated.current && !fromAnchor.current) {
                 blocker.proceed();
                 blockingPromise.resolve();
@@ -421,6 +422,9 @@ function Flow() {
     }, [blocker.state, blocker.location]);
 
     useEffect(() => {
+        if (blocker.state === 'blocked') {
+            return;
+        }
         if (navigated.current) {
             navigated.current = false;
             fireNavigated(location.pathname,location.search);

flow-tests/test-react-router/src/main/java/com/vaadin/flow/RouterLinkForwardingToParametersView.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2000-2024 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.vaadin.flow;
+
+import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.router.Route;
+import com.vaadin.flow.router.RouterLink;
+
+@Route("com.vaadin.flow.RouterLinkForwardingToParametersView")
+public class RouterLinkForwardingToParametersView extends Div {
+
+    public RouterLinkForwardingToParametersView() {
+        RouterLink link = new RouterLink("Forwarding view",
+                ForwardingToParametersView.class);
+        link.setId("forwardViewLink");
+        add(link);
+    }
+}

flow-tests/test-react-router/src/test/java/com/vaadin/flow/ForwardTargetIT.java

@@ -58,4 +58,27 @@ public void testSetParameterCalledOnlyOnceAfterForward() {
                         .filter(span -> span.getText().equals("setParameter"))
                         .count());
     }
+
+    // Test for https://github.com/vaadin/flow/issues/19822
+    @Test
+    public void testRouterLinkSetParameterCalledOnlyOnceAfterForward() {
+        getDriver().get(getTestURL(getRootURL(),
+                "/view/com.vaadin.flow.RouterLinkForwardingToParametersView",
+                null));
+        $("a").id("forwardViewLink").click();
+
+        try {
+            waitUntil(arg -> driver.getCurrentUrl().endsWith(
+                    "/view/com.vaadin.flow.ForwardTargetWithParametersView"));
+        } catch (TimeoutException e) {
+            Assert.fail("URL wasn't updated to expected one: "
+                    + "/view/com.vaadin.flow.ForwardTargetWithParametersView");
+        }
+
+        Assert.assertEquals("setParameter was called more than once", 1,
+                $(SpanElement.class).all().stream()
+                        .filter(span -> span.getText().equals("setParameter"))
+                        .count());
+    }
+
 }