Workaround for using the grails-schwartz-plugin in Grails 4

Version 1.0.1 of the grails-schwartz-plugin will not work with a grails 4 application as I recently found whilst trying to upgrade an app. You will get the following compilation error:

CONFIGURE SUCCESSFUL in 1s
Error |
Failed to compile create-job.groovy: startup failed:
create-job.groovy: 23: unable to resolve class grails.transaction.Transactional
 @ line 23, column 1.
   import grails.transaction.Transactional
   ^

1 error
 (Use --stacktrace to see the full trace)
Error |
Command \[run-app\] error: null (Use --stacktrace to see the full trace)

Process finished with exit code 1

The create-job.groovy file used by the create-job command imports the now defunct @Transactional AST transform which has now been moved to GORM.

I did some digging and found that there is a release candidate for version 2 fo the plugin(2.0.0.RC1). Using that instead gets rid of the compilation error but introduces a runtime error because the quartzScheduler bean can’t be created, a BeanCreationException is thrown. Digging deeper I realised that the SchwartzSchedulerFactoryBean class in the plugin uses a property from StdSchedulerFactory that is no longer available in the version of quartz schedular library that is being used.

This is because the version specified in the plugin’s dependencies:

String quartzVersion = '2.2.3'
compile 'org.quartz-scheduler:quartz:' + quartzVersion, {
  exclude module: 'c3p0'
}
compile 'org.quartz-scheduler:quartz-jobs:' + quartzVersion

Is overridden as shown by the gradle build scan I generated

schedular version is upgraded to 2.3.1

So as a hack you could enforce the required version by having it as a dependency in your own project’s build.gradle file. So the plugin dependency can be added like so:

compile 'com.agileorbit:schwartz:2.0.0.RC1'
// force version 2.2.3 of quartz
String quartzVersion = '2.2.3'
compile 'org.quartz-scheduler:quartz:' + quartzVersion, {
    exclude module: 'c3p0'
}
compile 'org.quartz-scheduler:quartz-jobs:' + quartzVersion

This is just a quick and dirty way to get things running again after an upgrade to grails 4. The new grails guide on scheduling now uses the native Spring Task Execution and Scheduling via @Scheduled so you would be better of reimplementing your scheduled tasks to use that.

As always, you can find an example of how to do this on github.