The nashorn is being used but not included in java 15+

[ali-v-1985]

In the handlebars.java 4.3.0 the problem with java 15+ supposed to be solved but the code below is still trying to get instance of nashorn script engine, which is not included in jdk any more.

handlebars.java/handlebars/src/main/java/com/github/jknack/handlebars/helper/DefaultHelperRegistry.java

Line 302 in ef79693

this.engine = new ScriptEngineManager().getEngineByName("nashorn");

The code is being referenced via the registerHelpers method of Handlebars when a js file is being used as the helper source.

Here is the pull request which addressed the issue
#867

The following is the stacktrace which resulted by calling registerHelpers method.

java.lang.NullPointerException: Cannot invoke "javax.script.ScriptEngine.put(String, Object)" because "this.engine" is null
  
  at com.github.jknack.handlebars.helper.DefaultHelperRegistry.engine(DefaultHelperRegistry.java:304)
  at com.github.jknack.handlebars.helper.DefaultHelperRegistry.registerHelpers(DefaultHelperRegistry.java:193)
  at com.github.jknack.handlebars.helper.DefaultHelperRegistry.registerHelpers(DefaultHelperRegistry.java:173)
  at com.github.jknack.handlebars.Handlebars.registerHelpers(Handlebars.java:750)

[jknack]

Right. Are you building with Maven? There is a maven profile for Java 15: https://github.com/jknack/handlebars.java/blob/master/handlebars/pom.xml#L381

The profile has the required dependency. Build is running without issue against Java 15. See here https://github.com/jknack/handlebars.java/actions/runs/1331083456

If you still have the issue try adding the dependency manually: https://search.maven.org/artifact/org.openjdk.nashorn/nashorn-core/15.3/jar

[comoroberto]

Hi @jknack,

same issue here with Java 15 and Java 17 invoking com.github.jknack.handlebars.Handlebars.registerHelpers

java.lang.NullPointerException: Cannot invoke "javax.script.ScriptEngine.put(String, Object)" because "this.engine" is null

It's a spring boot 2.5.8 project.

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>2.5.8</version>
	<relativePath />
</parent>

<properties>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
	<java.version>17</java.version>
	<spring-cloud.version>2020.0.3</spring-cloud.version>
</properties>

<dependency>
	<groupId>com.github.jknack</groupId>
	<artifactId>handlebars</artifactId>
	<version>4.3.0</version>
</dependency>

<dependency>
	<groupId>com.github.jknack</groupId>
	<artifactId>handlebars-jackson2</artifactId>
	<version>4.3.0</version>
</dependency>

<dependency>
	<groupId>com.github.jknack</groupId>
	<artifactId>handlebars-helpers</artifactId>
	<version>4.3.0</version>
</dependency>

<dependency>
	<groupId>org.openjdk.nashorn</groupId>
	<artifactId>nashorn-core</artifactId>
	<version>15.3</version>
</dependency>

[dpozinen]

@comoroberto where you able to resolve your issue?

I am using handlebars as part of git-changelog-lib and have added nashorn manually as well. Build is still failing with the mentioned NPE though.

[comoroberto]

@comoroberto where you able to resolve your issue?

I am using handlebars as part of git-changelog-lib and have added nashorn manually as well. Build is still failing with the mentioned NPE though.

Resolved. I had to clean my local .m2 repository and perform some maven clean on the project.

[MikalaiHarnouski]

I am using handlebars as part of git-changelog-lib with java 11. Build is still failing with the NPE .

[ERROR] GitChangelog
java.lang.NullPointerException
at com.github.jknack.handlebars.helper.DefaultHelperRegistry.engine (DefaultHelperRegistry.java:304)
at com.github.jknack.handlebars.helper.DefaultHelperRegistry.registerHelpers (DefaultHelperRegistry.java:193)
at com.github.jknack.handlebars.Handlebars.registerHelpers (Handlebars.java:859)

but nashorn is a part of java 11

[jonespm]

It looks like this was originally fixed for Java 11 on #702 and #731.

However that change was reverted in 865f2d7 and 4.3.0, 4.3.1 no longer work on Java 11 giving the original NPE again. Having to stay on 4.2.1 currently.