Spring Boot and Mustache default value

In Spring Boot + Mustache template environment, if we didn’t assign a value to a {{variable}} on the Mustache’s page, the jmustache will throws the following error messages :

com.samskivert.mustache.MustacheException$Context: No method or field with name 'variable' on line xx
	at com.samskivert.mustache.Template.checkForMissing(Template.java:316) ~[jmustache-1.13.jar:na]
	at com.samskivert.mustache.Template.getValue(Template.java:224) ~[jmustache-1.13.jar:na]
	at com.samskivert.mustache.Template.getValueOrDefault(Template.java:269) ~[jmustache-1.13.jar:na]

P.S Tested with Spring Boot 1.5.2.RELEASE

Solution 1

If the variable is optional, try to wrap like this:

  {{#variable}}
      {{.}}
  {{/variable}}

Solution 2

Alternatively, in Spring Boot, override the Mustache.Compiler to provide a default value globally:

package com.hostingcompass.web;
import com.samskivert.mustache.Mustache;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.mustache.MustacheEnvironmentCollector;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.core.env.Environment;
@SpringBootApplication
@ComponentScan({"com.mkyong"})
public class SpringBootWebApplication {
    public static void main(String[] args) {
        SpringApplication.run(SpringBootWebApplication.class, args);
    //Override MustacheAutoConfiguration to support defaultValue("")
    @Bean
    public Mustache.Compiler mustacheCompiler(Mustache.TemplateLoader mustacheTemplateLoader,
                                              Environment environment) {
        MustacheEnvironmentCollector collector = new MustacheEnvironmentCollector();
        collector.setEnvironment(environment);
		// default value
        Mustache.Compiler compiler = Mustache.compiler().defaultValue("")
			.withLoader(mustacheTemplateLoader)
            .withCollector(collector);
        return compiler;

References

1. Spring Boot Hello World Example – Mustache
2. jmustache – Default Values