Claus Ibsen created CAMEL-24986:
-----------------------------------
Summary: camel-rest: a REST producer sends the request when a path
parameter has no value, with the placeholder still in the uri
Key: CAMEL-24986
URL: https://issues.apache.org/jira/browse/CAMEL-24986
Project: Camel
Issue Type: Improvement
Components: rest, camel-rest-openapi
Reporter: Claus Ibsen
A REST producer sends the request even when a path parameter has no value, so
the call goes out with the placeholder still in it:
{noformat}
org.apache.camel.http.base.HttpOperationFailedException: HTTP operation failed
invoking
http://localhost:8080/api/stock/%7Bsku%7D/reserve with statusCode: 404
{noformat}
{{%7Bsku%7D}} is {{\{sku\}}}. Nothing says the parameter was not resolved; the
caller sees a 404 from the server and starts looking at the server.
h3. Where it comes from
{{RestProducer.prepareExchange}} resolves each path segment with
{{resolvePlaceholders}}, which reads a header and falls back to an exchange
variable:
{code:java}
String value = exchange.getMessage().getHeader(key, String.class);
if (value == null) {
value = exchange.getVariable(key, String.class);
}
if (value != null) {
res = res.substring(0, startIndex) + value + res.substring(endIndex + 1);
}
{code}
When neither has a value the placeholder is left as it is, and the request is
sent anyway. {{hasPath}} is set only when at least one segment resolved, so a
fully unresolved template falls through to the endpoint uri unchanged, and a
partly resolved one carries the rest into {{REST_HTTP_URI}}.
h3. What to do
# *Fail instead of sending it.* After the resolution loop, when the template
still holds a {{\{name\}}}, throw and say which parameter it is and where the
value comes from, e.g. "the path parameter \{sku\} of
/api/stock/\{sku\}/reserve has no value: set a header sku, or an exchange
variable, before the call". {{prepareUriTemplate=false}} remains the way to
send a uri with braces on purpose.
# *Say it before it runs.* The YAML validator knows the OpenAPI specification
already - {{OpenApiVerbs}} reads it for CAMEL-24844 phase B - so for a
{{rest-openapi}} producer it can see that {{reserveStock}} needs a {{sku}} path
parameter and that no step before the call sets that header, and report it at
write time.
h3. How often it happens
Measured on an overnight local-model benchmark (22 examples, 5 passes, 360
steps): this single mistake produced *2580* of the runtime errors, the most of
any cause, and appeared in *13 of 15 runs* across the three HTTP examples. The
model does set the header in the route; the value does not arrive, and nothing
in the failure says so. A person reading a 404 has the same problem.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
