Grails 3 domain composition using #Delegate - grails

Question

In my app I have a set of 1000 or so "HouseProto" domain objects, which have a bunch of static properties that I need in my "HouseInstance" object.
At scale, maybe there are large numbers of HouseInstance objects each modeled on the HouseProtos. Here is how I tried to model the HouseInstance domain object.
class HouseInstance {
#Delegate
HouseProto houseProto
User agent
static belongsTo=[world: World]
static constraints = {
agent nullable:true
}
}
HouseProto has a lot of fields like "squareFeet" and "bedroomCount" etc.
I used the #Delegate annotation because I'd like to be able to do something like
houseInstance.streetAddress
instead of
houseInstance.houseProto.streetAddress
but this fails on compile. Buried at the end of the console output below is a reference to the "features" field of HouseProto (a hasMany Set) which suggests that might have something to do with it. Remove the delegate annotation, though and it all works fine. (Feature is a domain class that belongsTo HouseProto.)
My question is simply whether or not the #Delegate annotation is incompatible with Domain classes because it interferes with GORM for some reason? It seems like it will do what I want if it can be made to compile.
HouseProto looks more or less like this:
class HouseProto {
def houseService
String streetAddress
Owner owner
Integer sqft
Double acreage
Integer bedroom
...
Double kitchenQuality =0
Double loanBalance =0
Neighborhood neighborhood
String toString() {
"$streetAddress"
}
static hasMany = [features: Feature]
static constraints = {
streetAddress nullable: false, unique: true;
owner nullable: true
sqft nullable: false
neighborhood nullable: false
}
}
The runtime console output starts with this:
ERROR org.springframework.boot.context.embedded.tomcat.TomcatStarter - Error starting Tomcat context. Exception: org.springframework.beans.factory.BeanCreationException. Message: Error creating bean with name 'grailsCacheFilter': Cannot create inner bean '(inner bean)#5ec1152d' of type [grails.plugin.cache.web.filter.simple.MemoryPageFragmentCachingFilter] while setting bean property 'filter'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name '(inner bean)#5ec1152d': Unsatisfied dependency expressed through method 'setUrlMappingsHandlerMapping' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'urlMappingsHandlerMapping': Unsatisfied dependency expressed through method 'setWebRequestInterceptors' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'openSessionInViewInterceptor': Cannot resolve reference to bean 'hibernateDatastore' while setting bean property 'hibernateDatastore'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateDatastore': Bean instantiation via constructor failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.grails.orm.hibernate.HibernateDatastore]: Constructor threw exception; nested exception is org.hibernate.MappingException: collection element mapping has wrong number of columns: com.grapevine.negotiator2.HouseInstance.features type: object
Disconnected from the target VM, address: '127.0.0.1:57570', transport: 'socket'
ERROR org.springframework.boot.SpringApplication - Application startup failed

Answer 1

As far as I aware #Delegate is not supported in domains, you may have more luck using a trait that both HouseInstance and HouseProto implement