如何在Camel Restlet中设置请求正文？

Question

I have a simple Camel get method and all I want to do is set the body to the result of a XSL transformation. How do I do this? The following code does not compile, but it shows what I want to achieve:

rest("/api")
    .get("/booksByAuthor/{author}")
    .route()
    .setBody(
        from("file:/conf.xml")
        .setHeader("author",simple("${header.author}"))
        .to("xslt:/transformers/booksByAuthor.xsl")
    );

Answer 1

You could use a processor to set the body to be the xml file, then pass it to your xslt. You don't need to have the file contents in the message body, just a handle to the file is enough for "xslt:". Something like

    rest("/api")
        .get("/booksByAuthor/{author}")
        .route()
        .process(exchange -> exchange.getIn().setBody(new File("/conf.xml")))
        .to("xslt:/transformers/booksByAuthor.xsl");

The author will already be in the message header, so you won't need to set it and you'll be able to access it in your xslt with

    <xsl:param name="author"/>
    <xsl:value-of select="$author"/>

I've just written the processor as a Java 8 lambda, but you could always use a separate class if you prefer.

If you want to get the source of your xml file into the message, rather than use the file handle, you could use the pollEnrich to read the file. You'll then need to use an aggregation strategy to ensure you keep the headers from the original message. Easiest way is probably just copy the body from the message with the xml to the original. Here's an example of how to do this.

    rest("/api")
        .get("/booksByAuthor/{author}")
        .route()
        .pollEnrich("file:/?fileName=conf.xml&noop=true", (original, xml) -> {
                original.getIn().setBody(xml.getIn().getBody());
                return original;})
        .to("xslt:/transformers/booksByAuthor.xsl");