Grails: service not being injected in controller when running plugin

Question

I'm creating a Grails (3.3.9) plugin to hold shared back-end code for some internal applications. For some reason, when I run the plugin to test it, my service is not being injected into my controller.

I've started with the default web-plugin profile, created a single domain class called Entry, and run generate-all to create a controller, service, and views. When I try to run my plugin as an application and view a single domain instance, I get the following error:

Cannot invoke method get() on null object. Stacktrace follows:

java.lang.reflect.InvocationTargetException: null
    at org.grails.core.DefaultGrailsControllerClass$ReflectionInvoker.invoke(DefaultGrailsControllerClass.java:211)
    at org.grails.core.DefaultGrailsControllerClass.invoke(DefaultGrailsControllerClass.java:188)
    at org.grails.web.mapping.mvc.UrlMappingsInfoHandlerAdapter.handle(UrlMappingsInfoHandlerAdapter.groovy:90)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55)
    at org.grails.web.servlet.mvc.GrailsWebRequestFilter.doFilterInternal(GrailsWebRequestFilter.java:77)
    at org.grails.web.filters.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:67)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException: Cannot invoke method get() on null object
    at com.mycompany.internal.EntryController.show(EntryController.groovy:18)
    ... 14 common frames omitted

The stacktrace takes me to line 18 in my controller:

def show(Long id) {
    respond entryService.get(id)
}

This suggests to me that entryService is null.

My domain class looks like this:

class Entry {

    String entryCode
    String description
}

The controller is as follows:

class EntryController {

    EntryService entryService

    static allowedMethods = [save: "POST", update: "PUT", delete: "DELETE"]

    def index(Integer max) {
        params.max = Math.min(max ?: 10, 100)
        respond entryService.list(params), model:[entryCount: entryService.count()]
    }

    def show(Long id) {
        respond entryService.get(id)
    }

    //snipped for brevity

And the service looks like this:

@Service(Entry)
interface EntryService {

    Entry get(Serializable id)

    //snipped for brevity

}

Based on the Grails plugin documentation, I would expect to be able to run the plugin standalone like any other application, and in normal applications, defining the service as an interface works fine. If I install this plugin to my local maven cache and use it in an application, it works exactly as I would expect; I am able to hit the controller's show endpoint and get back a result from my database.

At one point I tried implementing the service as a class rather than having it be an interface, but then I receive this error:

URI
/entry/index
Class
java.lang.IllegalStateException
Message
null
Caused by
Either class [com.mycompany.internal.Entry] is not a domain class or GORM has not been initialized correctly or has already been shutdown. Ensure GORM is loaded and configured correctly before calling any methods on a GORM entity.

What am I missing about how to set up and run a Grails plugin correctly?

Answer 1

Finally found an answer by digging into the GORM issue: class Authority is not a domain class or GORM has not been initialized correctly or has already been shutdown

Apparently the root of the problem was the need to add compile "org.grails.plugins:hibernate5" to my dependencies block in build.gradle. The weird thing is that the web-plugin profile provides the create-domain-class command, so I would think GORM and Hibernate support would be included by default, but I'm apparently misunderstanding some aspects of how plugins are supposed to work.