Handle redirects

Fixes micronaut-projects#360
Instead of passing a missing body to the view do an early exit if a redirect is encountered.

test-suite/src/test/java/io/micronaut/views/model/RedirectFruitsController.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2017-2021 original authors
+ *
+ * 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 io.micronaut.views.model;
+
+import io.micronaut.context.annotation.Requires;
+import io.micronaut.core.annotation.Introspected;
+import io.micronaut.core.util.CollectionUtils;
+import io.micronaut.http.HttpResponse;
+import io.micronaut.http.annotation.Controller;
+import io.micronaut.http.annotation.Get;
+import io.micronaut.security.annotation.Secured;
+import io.micronaut.security.rules.SecurityRule;
+import io.micronaut.views.View;
+
+import java.net.URI;
+import java.util.Collections;
+import java.util.Map;
+
+@Secured(SecurityRule.IS_AUTHENTICATED)
+@Requires(property = "spec.name", value = "RedirectModelAndViewSpec")
+@Controller
+public class RedirectFruitsController {
+
+    @View("fruits")
+    @Get
+    public HttpResponse<Fruit> index() {
+        return HttpResponse.ok(new Fruit("apple", "red"));
+    }
+
+    @View("fruits")
+    @Get("/redirect")
+    public HttpResponse<Fruit> redirect() {
+        return HttpResponse.redirect(URI.create("/"));
+    }
+
+    @Introspected
+    public static class Fruit {
+        private final String name;
+        private final String color;
+
+        public Fruit(String name, String color) {
+            this.name = name;
+            this.color = color;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public String getColor() {
+            return color;
+        }
+    }
+}

test-suite/src/test/java/views/RedirectModelAndViewTest.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2017-2021 original authors
+ *
+ * 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 views;
+
+import io.micronaut.context.ApplicationContext;
+import io.micronaut.core.util.CollectionUtils;
+import io.micronaut.core.util.StringUtils;
+import io.micronaut.http.HttpRequest;
+import io.micronaut.http.HttpResponse;
+import io.micronaut.http.HttpStatus;
+import io.micronaut.http.client.BlockingHttpClient;
+import io.micronaut.http.client.DefaultHttpClientConfiguration;
+import io.micronaut.http.client.HttpClient;
+import io.micronaut.http.client.HttpClientConfiguration;
+import io.micronaut.runtime.server.EmbeddedServer;
+import io.micronaut.views.model.RedirectFruitsController;
+import io.micronaut.views.model.UnmodifiableFruitsController;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+// Issue: https://github.com/micronaut-projects/micronaut-views/issues/360
+class RedirectModelAndViewTest {
+
+    @Test
+    void aRedirectingResponseIsPassedThrough() {
+        EmbeddedServer embeddedServer = ApplicationContext.run(EmbeddedServer.class, CollectionUtils.mapOf(
+                "spec.name", "RedirectModelAndViewSpec",
+                "micronaut.views.soy.enabled", StringUtils.FALSE));
+
+        DefaultHttpClientConfiguration configuration = new DefaultHttpClientConfiguration();
+        configuration.setFollowRedirects(false);
+        HttpClient httpClient = HttpClient.create(embeddedServer.getURL(), configuration);
+
+        //given:
+        BlockingHttpClient client = httpClient.toBlocking();
+        //expect:
+        assertTrue(embeddedServer.getApplicationContext().containsBean(RedirectFruitsController.class));
+
+        //when:
+        HttpRequest<?> request = HttpRequest.GET("/redirect").basicAuth("john", "secret");
+        HttpResponse<String> response = client.exchange(request, String.class);
+
+        //then:
+        assertEquals(HttpStatus.MOVED_PERMANENTLY, response.status());
+
+        //when:
+        String html = response.body();
+
+        //then:
+        assertNull(html);
+
+        //cleanup:
+        httpClient.close();
+
+        //and:
+        embeddedServer.close();
+    }
+
+}

views-core/src/main/java/io/micronaut/views/ViewsFilter.java

@@ -21,6 +21,7 @@
 import io.micronaut.core.annotation.AnnotationMetadata;
 import io.micronaut.core.annotation.NonNull;
 import io.micronaut.core.io.Writable;
+import io.micronaut.http.HttpStatus;
 import io.micronaut.http.MediaType;
 import io.micronaut.http.MutableHttpResponse;
 import io.micronaut.http.HttpAttributes;
@@ -78,6 +79,10 @@ public final Publisher<MutableHttpResponse<?>> doFilter(HttpRequest<?> request,
                                                             ServerFilterChain chain) {
         return Flux.from(chain.proceed(request))
             .switchMap(response -> {
+                if(response.getStatus() == HttpStatus.MOVED_PERMANENTLY) {
+                    LOG.debug("redirect, passing through");
+                    return Flux.just(response);
+                }
                 Optional<String> optionalView = viewsResolver.resolveView(request, response);
                 if (!optionalView.isPresent()) {
                     LOG.debug("no view found");