How do you generate an XML with Thymeleaf in Spring Boot?

Question

I have a web application I'm building with Spring Boot, Kotlin and Thymeleaf. I have some HTML templates working, but I want to make one return an XML file. This XML would be a Thymeleaf template, using Thymeleaf attributes. What's the correct way of doing that in Spring Boot? Also, the XML should be downloaded.

I've seen this: Spring Boot & Thymeleaf with XML Templates, but it seems that would switch Thymeleaf to generate XMLs site-wide, not just for a single controller.

Answer 1

Alright then, one way of doing it would be configuring the Thymeleaf engine in a single method. For example:

@GetMapping("/xml")
public void xml(HttpServletResponse res) throws Exception {
    SpringResourceTemplateResolver resolver = new SpringResourceTemplateResolver();
    resolver.setApplicationContext(new AnnotationConfigApplicationContext());
    resolver.setPrefix("classpath:/xml/");
    resolver.setSuffix(".xml");
    resolver.setCharacterEncoding("UTF-8");
    resolver.setTemplateMode(TemplateMode.XML);

    SpringTemplateEngine engine = new SpringTemplateEngine();
    engine.setTemplateResolver(resolver);

    Context ctx = new Context();
    ctx.setVariable("notes", Arrays.asList("one note", "two note"));
    String xml = engine.process("template", ctx);

    res.setHeader("Content-Disposition", "attachment; filename=template.xml");
    res.setContentType("application/xml");
    PrintWriter writer = res.getWriter();
    writer.print(xml);
    writer.close();
}

Where the template is located in src/main/resources/xml/template.xml. You set your model variables using the ctx.setVariable() method.