Grails - Hibernate-safe domain class property editor

GrailsHibernateSafeDomainClassPropertyEditor.groovy

import static org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsHibernateUtil.unwrapIfProxy

public class DomainClassLookupPropertyEditor extends PropertyEditorSupport {
 
    Class domainClass
    String property
    Boolean doAssert = true
 
    String getAsText() {
        value."$property"
    }
 
    void setAsText(String text) {
       def alreadyInSessionValue = searchValueInCurrentSession(text)
       value = alreadyInSessionValue != null ?
         domainClass.load(alreadyInSessionValue.id) : searchValueInNewSession(text)
       assert doAssert && value, "no $domainClass found for $property '$text'"
    }

   private searchValueInNewSession(String text) {
      domainClass.withNewSession {
         domainClass."findBy${property.capitalize()}"(text)
      }
   }

   private searchValueInCurrentSession(String text) {
      domainClass.withSession { session ->
         session.persistenceContext.entityEntries.find { instance, persistenceEntry ->
            unwrapIfProxy(instance).getClass() == domainClass &&
               instance[property].toString() == text
         }?.key
      }
   }

   static DomainClassLookupPropertyEditor newInstance(Class domainClass, String propToLookup) {
       new DomainClassLookupPropertyEditor(domainClass: domainClass, property: propToLookup)
    }
 
}


public class MyPropertyEditorRegistrar implements PropertyEditorRegistrar {
   
   static Map<Class, String> domainClassByPropertyCustomBinders = [
      (User): 'id', (Role): 'authority'
   ]
   
   public void registerCustomEditors(PropertyEditorRegistry propertyEditorRegistry) {
      domainClassByPropertyCustomBinders.each { domainClass, prop ->
         registerDomainClassLookupPropEditor(propertyEditorRegistry, domainClass, prop)
      }
   }
   
   private registerDomainClassLookupPropEditor(
      PropertyEditorRegistry propertyEditorRegistry, Class domainClass, String propToLookup
   ) {
      propertyEditorRegistry.registerCustomEditor(
         domainClass, DomainClassLookupPropertyEditor.newInstance(domainClass, propToLookup)
      )
   }
}