How to call public Java variable in FreeMarker

Question

I'm trying to call a Java method in my FreeMarker template that uses a public static Java variable as one of its parameters. For example, if the FreeMarker code in a test.ftl is this:

${javaClass.getSomething(javaClass.VARIABLE)}

and if the class JavaClass looks like this:

public class JavaClass {

    public static final int VARIABLE = 1;

    public String getSomething(int var) {
    ...
    }

I receive errors when using the template that look like this:

[echo] Expression JavaClass is undefined on line 40, column 81 in com/test/template/path/test.ftl. [echo] The problematic instruction: [echo] ---------- [echo] 03:53:01,146 ERROR [main][runtime:96] Template processing error: "Expression JavaClass is undefined on line 40, column 81 in com/test/template/path/test.ftl" [echo] [echo] ==> ${javaClass.getSomething(javaClass.VARIABLE)} [on line 40, column 25 in com/test/template/path/test.ftl] Expression JavaClass is undefined on line 40, column 81 in com/test/template/path/test.ftl. [echo] [echo] ----------The problematic instruction: [echo] [echo] [echo] ---------- [echo] Java backtrace for programmers: [echo] ---------- [echo] ==> ${javaClass.getSomething(javaClass.VARIABLE)} [on line 40, column 25 in com/test/template/path/test.ftl]freemarker.core.InvalidRe ferenceException: Expression JavaClass is undefined on line 40, column 81 in com/test/template/path/test.ftl. ... ...

This error is complaining that it doesn't like the javaClass.VARIABLE and throws the InvalidReferenceException. I've tried specifying this in other different ways, such as JavaClass.VARIABLE, ${javaClass.VARIABLE}, and ${JavaClass.VARIABLE}, but they all throw errors.

How would you call a public Java variable from within a Java method in a FreeMarker (.ftl) template?

Answer 1

Freemarker's data model doesn't map static fields on objects passed in automatically, so you'd have to use a beanwrapper http://freemarker.org/docs/pgui_misc_beanwrapper.html.

import freemarker.ext.beans.BeansWrapper;

BeansWrapper w = new BeansWrapper(); 
TemplateHashModel statics = w.getStaticModels();
model.addAttribute("myVariable", statics);

then in your template, use

${myVariable["fully.qualified.package.ClassName"].FIELD_NAME}