fix: show available client routes

flow-server/src/main/java/com/vaadin/flow/router/AbstractRouteNotFoundError.java

@@ -22,7 +22,10 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
 import java.util.TreeMap;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
 import org.apache.commons.io.IOUtils;
@@ -35,7 +38,8 @@
 import com.vaadin.flow.component.Component;
 import com.vaadin.flow.component.Html;
 import com.vaadin.flow.component.Tag;
-import com.vaadin.flow.internal.hilla.EndpointRequestUtil;
+import com.vaadin.flow.di.Lookup;
+import com.vaadin.flow.router.internal.ClientRoutesProvider;
 import com.vaadin.flow.server.HttpStatusCode;
 import com.vaadin.flow.server.VaadinService;
 import com.vaadin.flow.server.frontend.FrontendUtils;
@@ -116,8 +120,10 @@ private static String readHtmlFile(String templateName) {
     }
 
     private String getRoutes(BeforeEnterEvent event) {
+        List<Element> routeElements = new ArrayList<>();
         List<RouteData> routes = event.getSource().getRegistry()
                 .getRegisteredRoutes();
+
         Map<String, Class<? extends Component>> routeTemplates = new TreeMap<>();
 
         for (RouteData route : routes) {
@@ -127,14 +133,21 @@ private String getRoutes(BeforeEnterEvent event) {
                     .put(alias.getTemplate(), alias.getNavigationTarget()));
         }
 
-        List<Element> routeElements = new ArrayList<>();
         routeTemplates.forEach(
                 (k, v) -> routeElements.add(routeTemplateToHtml(k, v)));
 
+        routeElements.addAll(getClientRoutes());
         return routeElements.stream().map(Element::outerHtml)
                 .collect(Collectors.joining());
     }
 
+    private List<Element> getClientRoutes() {
+        return FrontendUtils.getClientRoutes().stream()
+                .filter(route -> !route.contains("$layout"))
+                .map(route -> route.replace("$index", ""))
+                .map(this::clientRouteToHtml).toList();
+    }
+
     private Element routeTemplateToHtml(String routeTemplate,
             Class<? extends Component> navigationTarget) {
         String text = routeTemplate;
@@ -156,6 +169,23 @@ private Element routeTemplateToHtml(String routeTemplate,
         }
     }
 
+    private Element clientRouteToHtml(String route) {
+        String text = route;
+        if (text.isEmpty()) {
+            text = "<root>";
+        }
+        if (!route.contains(":")) {
+            return elementAsLink(route, text);
+        } else {
+            if (Pattern.compile(":\\w+\\?").matcher(route).find()) {
+                text += " (supports optional parameter)";
+            } else {
+                text += " (requires parameter)";
+            }
+            return new Element(Tag.LI).text(text);
+        }
+    }
+
     private Element elementAsLink(String url, String text) {
         Element link = new Element(Tag.A).attr("href", url).text(text);
         return new Element(Tag.LI).appendChild(link);

flow-server/src/main/java/com/vaadin/flow/router/internal/ClientRoutesProvider.java

@@ -0,0 +1,33 @@
+/*
+ * 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.router.internal;
+
+import java.io.Serializable;
+import java.util.List;
+
+/**
+ * Interface for providing client side routes.
+ */
+public interface ClientRoutesProvider extends Serializable {
+
+    /**
+     * Get a list of client side routes.
+     *
+     * @return a list of client side routes. Not null.
+     */
+    List<String> getClientRoutes();
+}

flow-server/src/main/java/com/vaadin/flow/server/frontend/FrontendUtils.java

@@ -53,6 +53,7 @@
 import com.vaadin.flow.internal.Pair;
 import com.vaadin.flow.internal.StringUtil;
 import com.vaadin.flow.internal.hilla.EndpointRequestUtil;
+import com.vaadin.flow.router.internal.ClientRoutesProvider;
 import com.vaadin.flow.server.AbstractConfiguration;
 import com.vaadin.flow.server.Constants;
 import com.vaadin.flow.server.VaadinService;
@@ -1434,4 +1435,20 @@ public static boolean isReactModuleAvailable(Options options) {
             return false;
         }
     }
+
+    /**
+     * Get all available client routes in a distinct list of route paths
+     * collected from all {@link ClientRoutesProvider} implementations found
+     * with Vaadin {@link Lookup}.
+     *
+     * @return a list of available client routes
+     */
+    public static List<String> getClientRoutes() {
+        return Optional.ofNullable(VaadinService.getCurrent())
+                .map(VaadinService::getContext).stream()
+                .flatMap(ctx -> ctx.getAttribute(Lookup.class)
+                        .lookupAll(ClientRoutesProvider.class).stream())
+                .flatMap(provider -> provider.getClientRoutes().stream())
+                .filter(Objects::nonNull).distinct().toList();
+    }
 }

flow-tests/vaadin-spring-tests/test-spring-boot-only-prepare/src/main/java/com/vaadin/flow/spring/test/TestServletInitializer.java

@@ -15,12 +15,17 @@
  */
 package com.vaadin.flow.spring.test;
 
+import java.util.List;
+
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
 
+import com.vaadin.flow.router.internal.ClientRoutesProvider;
+
 @SpringBootApplication
 @Configuration
 @EnableWebSecurity
@@ -30,4 +35,25 @@ public static void main(String[] args) {
         SpringApplication.run(TestServletInitializer.class, args);
     }
 
+    @Bean
+    public ClientRoutesProvider hillaClientRoutesProvider() {
+        return new ClientRoutesProvider() {
+            @Override
+            public List<String> getClientRoutes() {
+                return List.of("$index", "$layout", "/hilla",
+                        "/hilla/person/:id", "/hilla/persons/:id?");
+            }
+        };
+    }
+
+    @Bean
+    public ClientRoutesProvider anotherhillaClientRoutesProvider() {
+        return new ClientRoutesProvider() {
+            @Override
+            public List<String> getClientRoutes() {
+                return List.of("/$layout", "/hilla", "/hilla/hilla/$index",
+                        "/anotherhilla");
+            }
+        };
+    }
 }

flow-tests/vaadin-spring-tests/test-spring-common/src/test/java/com/vaadin/flow/spring/test/HillaRoutesRegisteredIT.java

@@ -0,0 +1,50 @@
+/*
+ * 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.spring.test;
+
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class HillaRoutesRegisteredIT extends AbstractSpringTest {
+
+    @Test
+    public void assertClientRoutesRegistered() {
+        String nonExistingRoutePath = "non-existing-route";
+        getDriver().get(getContextRootURL() + '/' + nonExistingRoutePath);
+        waitForDevServer();
+        Assert.assertTrue(getDriver().getPageSource().contains(String
+                .format("Could not navigate to '%s'", nonExistingRoutePath)));
+
+        if (getDriver().getPageSource().contains(
+                "This detailed message is only shown when running in development mode.")) {
+            var expectedClientRoutes = List.of("<a href=\"\">&lt;root&gt;</a>",
+                    "<a href=\"/hilla\">/hilla</a>",
+                    "<li>/hilla/person/:id (requires parameter)</li>",
+                    "<li>/hilla/persons/:id? (supports optional parameter)</li>",
+                    "<a href=\"/hilla/hilla/\">/hilla/hilla/</a>",
+                    "<a href=\"/anotherhilla\">/anotherhilla</a>");
+            for (String route : expectedClientRoutes) {
+                Assert.assertTrue(
+                        String.format("Expected client route %s is missing",
+                                route),
+                        getDriver().getPageSource().contains(route));
+            }
+        }
+    }
+}