Add formating function to Template in Java Mustache

Question

I have a Java Mustache app and I need to apply a function to render it in currency format

I have my template

{{#currency}}{{number_to_format}}{{/currency}}

And my function

HashMap<String, Object> scopes = new HashMap<String, Object>();

//Add date 
scopes.put("number_to_format",BigDecimal.ONE);
scopes.put("currency", new TemplateFunction() {
          public String apply(String input) {
            NumberFormat currency = NumberFormat.getCurrencyInstance();
            return currency.format(new BigDecimal(input));                          
              
          }
      }
);

MustacheFactory mf = new DefaultMustacheFactory();
Mustache mustache = mf.compile("template.mustache");
mustache.execute(writer,scopes).flush();

I am unable to get the value in the "input" variable, i always get the variable name "number_to_format". If I return a value in the function it will be rendered.

How can i get the numeric value of my vairable in input?

Answer 1

The input variable is an incoming template, you need to render it to get the value
Therefore again render it with same factory and scopes and get the value

HashMap<String, Object> scopes = new HashMap<String, Object>();
        
final MustacheFactory mf = new DefaultMustacheFactory();
// Add date
scopes.put("number_to_format", BigDecimal.ONE);
scopes.put("currency", new TemplateFunction() {
    public String apply(String input) {
        //render the input as template to get the value
        Mustache mustache = mf.compile(new StringReader(input), "");
        StringWriter out = new StringWriter();
        mustache.execute(out, scopes);
        
        NumberFormat currency = NumberFormat.getCurrencyInstance(Locale.US);
        return currency.format(new BigDecimal(out.toString()));

    }
});


Mustache mustache = mf.compile("template.mustache");
mustache.execute(new PrintWriter(System.out), scopes).flush();

Otherwise get the value from HashMap by checking the input

if(input.equals("{{number_to_format}}")){
    input = scopes.get("number_to_format").toString();
}

NumberFormat currency = NumberFormat.getCurrencyInstance(Locale.US);
return currency.format(new BigDecimal(input));

Otherwise remove the "{{" and "}}" and use it as a key to hashmap