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new 3f9f77926b3a CAMEL-24986: a REST producer says which path parameter
has no value (#26843)
3f9f77926b3a is described below
commit 3f9f77926b3ae47fb2bd73914b4ee8861182ae19
Author: Claus Ibsen <[email protected]>
AuthorDate: Thu Sep 24 13:05:27 2026 +0200
CAMEL-24986: a REST producer says which path parameter has no value (#26843)
When a path parameter has no value the request is sent with the placeholder
still in the path, and the service answers 404 for a path that holds a {name}
with nothing saying why. resolvePlaceholders reads a header and falls back to
an exchange variable, and leaves the placeholder as it is when neither has a
value.
It now says which parameter it was:
The path parameter {sku} of /api/stock/{sku}/reserve has no value: set
the header sku, or an exchange variable of that name, before the call. The
request is sent with {sku} in the path, which the service is unlikely to
answer. This is logged once per parameter.
It warns rather than fails, because both shapes are deliberate and tested:
a partly resolved template keeps the rest of its placeholders, and a template
where nothing resolved is not an error either. A first attempt threw instead,
broke RestProducerPathTest and was reverted in 7aec6a1a2b9b; the new test
asserts the request is still sent so that cannot happen again unnoticed. Once
per parameter rather than per message, since a route missing a value is missing
it for every message.
Closes #26843
---
.../apache/camel/component/rest/RestProducer.java | 40 +++++++
.../rest/RestProducerUnresolvedPathWarnTest.java | 117 +++++++++++++++++++++
2 files changed, 157 insertions(+)
diff --git
a/components/camel-rest/src/main/java/org/apache/camel/component/rest/RestProducer.java
b/components/camel-rest/src/main/java/org/apache/camel/component/rest/RestProducer.java
index 8b8abd47c963..f668f3de9fcf 100644
---
a/components/camel-rest/src/main/java/org/apache/camel/component/rest/RestProducer.java
+++
b/components/camel-rest/src/main/java/org/apache/camel/component/rest/RestProducer.java
@@ -23,7 +23,9 @@ import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Locale;
import java.util.Map;
+import java.util.Set;
import java.util.StringJoiner;
+import java.util.concurrent.ConcurrentHashMap;
import org.apache.camel.AsyncCallback;
import org.apache.camel.AsyncProcessor;
@@ -43,6 +45,8 @@ import org.apache.camel.support.service.ServiceHelper;
import org.apache.camel.util.FileUtil;
import org.apache.camel.util.ObjectHelper;
import org.apache.camel.util.URISupport;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
import static org.apache.camel.util.ObjectHelper.isEmpty;
import static org.apache.camel.util.ObjectHelper.isNotEmpty;
@@ -52,6 +56,11 @@ import static org.apache.camel.util.ObjectHelper.isNotEmpty;
*/
public class RestProducer extends DefaultAsyncProducer {
+ private static final Logger LOG =
LoggerFactory.getLogger(RestProducer.class);
+
+ /** The path parameters already warned about, so a misconfigured route
says it once and not per message. */
+ private final Set<String> warnedParameters = ConcurrentHashMap.newKeySet();
+
private final CamelContext camelContext;
private final RestConfiguration configuration;
private boolean prepareUriTemplate = true;
@@ -167,6 +176,16 @@ public class RestProducer extends DefaultAsyncProducer {
}
}
resolvedUriTemplate = uriTemplateBuilder.toString();
+
+ // the request is sent with the placeholder still in the path,
and the service answers 404 for a
+ // path that holds a {name}, so say which parameter had no
value (CAMEL-24986)
+ String unresolved = firstPlaceholder(resolvedUriTemplate);
+ if (unresolved != null && warnedParameters.add(unresolved)) {
+ LOG.warn("The path parameter {{}} of {} has no value: set
the header {}, or an exchange variable"
+ + " of that name, before the call. The request is
sent with {{}} in the path, which the"
+ + " service is unlikely to answer. This is logged
once per parameter.",
+ unresolved, resolvedUriTemplate, unresolved,
unresolved);
+ }
}
}
@@ -221,6 +240,27 @@ public class RestProducer extends DefaultAsyncProducer {
}
}
+ /**
+ * The name of the first {@code {name}} left in the template, or null when
every one of them was resolved. Only a
+ * name counts, so a uri that holds braces for another reason is left
alone (CAMEL-24986).
+ */
+ private static String firstPlaceholder(String uriTemplate) {
+ int start = uriTemplate.indexOf('{');
+ while (start >= 0) {
+ int end = uriTemplate.indexOf('}', start);
+ if (end < 0) {
+ return null;
+ }
+ String name = uriTemplate.substring(start + 1, end);
+ if (!name.isEmpty() && name.chars().allMatch(
+ c -> Character.isLetterOrDigit(c) || c == '_' || c == '-'
|| c == '.')) {
+ return name;
+ }
+ start = uriTemplate.indexOf('{', end);
+ }
+ return null;
+ }
+
/**
* Replaces placeholders "{}" with message header or exchange variable
values.
*
diff --git
a/core/camel-core/src/test/java/org/apache/camel/component/rest/RestProducerUnresolvedPathWarnTest.java
b/core/camel-core/src/test/java/org/apache/camel/component/rest/RestProducerUnresolvedPathWarnTest.java
new file mode 100644
index 000000000000..934552a16aa6
--- /dev/null
+++
b/core/camel-core/src/test/java/org/apache/camel/component/rest/RestProducerUnresolvedPathWarnTest.java
@@ -0,0 +1,117 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.camel.component.rest;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import org.apache.camel.Exchange;
+import org.apache.camel.Message;
+import org.apache.camel.component.log.ConsumingAppender;
+import org.apache.camel.impl.DefaultCamelContext;
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.Appender;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * A path parameter with no value leaves its {name} in the uri and the service
answers 404 for it, so the producer says
+ * which parameter it was. The request is still sent, as it was before
(CAMEL-24986).
+ */
+public class RestProducerUnresolvedPathWarnTest {
+
+ private final List<String> warnings = new CopyOnWriteArrayList<>();
+ private final RestComponent restComponent;
+ private Appender appender;
+
+ public RestProducerUnresolvedPathWarnTest() {
+ DefaultCamelContext context = new DefaultCamelContext();
+ context.addComponent("mock-rest", new RestEndpointTest.MockRest());
+ restComponent = new RestComponent();
+ restComponent.setCamelContext(context);
+ }
+
+ @BeforeEach
+ public void before() {
+ appender = ConsumingAppender.newAppender(
+ RestProducer.class.getName(), "UnresolvedPath", Level.WARN,
+ event ->
warnings.add(event.getMessage().getFormattedMessage()));
+ }
+
+ @AfterEach
+ public void after() {
+ if (appender != null) {
+ appender.stop();
+ }
+ }
+
+ private RestProducer createProducer(String uri) throws Exception {
+ final RestEndpoint restEndpoint = (RestEndpoint)
restComponent.createEndpoint(uri);
+ restEndpoint.setConsumerComponentName("mock-rest");
+ restEndpoint.setParameters(new HashMap<>());
+ restEndpoint.setHost("http://localhost";);
+ restEndpoint.setBindingMode("json");
+ return (RestProducer) restEndpoint.createProducer();
+ }
+
+ @Test
+ public void testSaysWhichParameterHasNoValue() throws Exception {
+ RestProducer producer = createProducer("rest:get:list/{id}/{val}");
+ Exchange exchange = producer.createExchange();
+ Message message = exchange.getIn();
+ message.setHeader("id", 1);
+
+ producer.process(exchange);
+
+ // the request is still sent, with the placeholder in it, as before
+ assertEquals("http://localhost/list/1/{val}";,
message.getHeader(Exchange.REST_HTTP_URI));
+ assertEquals(1, warnings.size(), warnings.toString());
+ assertTrue(warnings.get(0).contains("{val}"), warnings.get(0));
+ assertTrue(warnings.get(0).contains("set the header val"),
warnings.get(0));
+ }
+
+ @Test
+ public void testSaysItOncePerParameter() throws Exception {
+ RestProducer producer = createProducer("rest:get:list/{id}");
+
+ for (int i = 0; i < 3; i++) {
+ Exchange exchange = producer.createExchange();
+ producer.process(exchange);
+ }
+
+ // a route that is wrong is wrong for every message, so it is said once
+ assertEquals(1, warnings.size(), warnings.toString());
+ assertTrue(warnings.get(0).contains("{id}"), warnings.get(0));
+ }
+
+ @Test
+ public void testSaysNothingWhenEveryParameterHasAValue() throws Exception {
+ RestProducer producer = createProducer("rest:get:list/{id}");
+ Exchange exchange = producer.createExchange();
+ exchange.getIn().setHeader("id", 1);
+
+ producer.process(exchange);
+
+ assertEquals("http://localhost/list/1";,
exchange.getIn().getHeader(Exchange.REST_HTTP_URI));
+ assertTrue(warnings.isEmpty(), warnings.toString());
+ }
+}
