Camel: how to manipulate output message/set header based on xpath expression

Question

I'm trying to dynamically create a RESTful URL based on the incoming XML:

Input:

<message>
   <request name="John"/>
</message>

I want to route it like this:

http://myhost:8080/myservice?name=John

I know how to set URL parameters using setHeader but I don't know how to extract the attribute values from the input message. The SOOPER_XPATH expression I'm looking for might look like this:

from("direct:start")
  .setHeader(Exchange.HTTP_QUERY,
     simple("name=$SOOPER_XPATH(${in.body}, '//request/@name')")
  .to("http://myhost:8080/myservice").log("Received response: ${in.body});

Indeed tThe xpath in the snippet had a typo, //request@name instead of //request/@name, sorry about that. But my problem is not with the xpath expression. — Ya.
– Ya., Commented May 16, 2014 at 23:36

Daniel · Accepted Answer · 2014-05-14 06:12:55Z

1

There are probably several ways to do it, this is what we do in one of my projects, works fine:

exchange.getIn().setHeader(XPathBuilder.xpath("/message/messageID/text()").evaluate(exchange,String.class));

We do this inside a processor, but you could probably use the XPathBuilder directly in a route as well.

It's really just a matter of getting the xpath right. I usually use some tool like http://www.xpathtester.com/xpath to test my xpaths.

answered May 14, 2014 at 6:12

Daniel

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1 Comment

Ya. Over a year ago

Thanks, I haven't been able to figure out how to use it in a route. Using processor instead.

Peter Keller · Accepted Answer · 2014-06-23 20:08:34Z

0

In order to set the header in the route outside of a Processor, use:

from("direct:start")
    .setHeader(Exchange.HTTP_QUERY, xpath("//request@name").stringResult())
    .to("http://myhost:8080/myservice").log("Received response: ${in.body}");

edited Jun 23, 2014 at 20:08

answered May 16, 2014 at 15:57

Peter Keller

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