How can I introspect a freemarker template to find out what variables it uses?

Question

I\'m not at all sure that this is even a solvable problem, but supposing that I have a freemarker template, I\'d like to be able to ask the template what variables it uses.<

Answer 1

one other way to get the variables from java. This just tries to process the template and catch the InvalidReferenceException to find all the variables in a freemarker-template

 /**
 * Find all the variables used in the Freemarker Template
 * @param templateName
 * @return
 */
public Set getTemplateVariables(String templateName) {
    Template template = getTemplate(templateName);
    StringWriter stringWriter = new StringWriter();
    Map dataModel = new HashMap<>();
    boolean exceptionCaught;

    do {
        exceptionCaught = false;
        try {
            template.process(dataModel, stringWriter);
        } catch (InvalidReferenceException e) {
            exceptionCaught = true;
            dataModel.put(e.getBlamedExpressionString(), "");
        } catch (IOException | TemplateException e) {
            throw new IllegalStateException("Failed to Load Template: " + templateName, e);
        }
    } while (exceptionCaught);

    return dataModel.keySet();
}

private Template getTemplate(String templateName) {
    try {
        return configuration.getTemplate(templateName);
    } catch (IOException e) {
        throw new IllegalStateException("Failed to Load Template: " + templateName, e);
    }
}