Hibernate Subselect Entity not supported by EntityMetamodelImpl

[jwgmeligmeyling]

Description

After playing a bit with table functions (see also #181), I had the idea to experiment with mapping a generate_series query to an entity using the @Subselect annotation. Find below the produced stack trace.

A trivial work around is to wrap the query into to a view and map that instead. I am uncertain whether a fix for this is worthwhile, but it could perhaps be a step towards implementing table functions (#181).

package com.pallasathenagroup.entities.series;

import lombok.Data;
import lombok.EqualsAndHashCode;
import org.hibernate.annotations.Immutable;
import org.hibernate.annotations.Subselect;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import java.time.LocalDateTime;

@Data
@Entity
@Immutable
@Subselect("select start_date_time, start_date_time + interval '1 year' as end_date_time " +
    "from generate_series('2016-09-01'::timestamp, date_trunc('year', now()) + interval '8 months', '1 year') as start_date_time")
@EqualsAndHashCode(of = {"start"})
public class CollegeYearSeries implements Comparable<CollegeYearSeries> {

    @Id
    @Column(name = "start_date_time")
    private LocalDateTime start;

    @Column(name = "end_date_time")
    private LocalDateTime end;

    @Override
    public int compareTo(CollegeYearSeries o) {
        return getStart().compareTo(o.getStart());
    }
}

Caused by: java.lang.NullPointerException
	at com.blazebit.persistence.impl.hibernate.HibernateExtendedQuerySupport.getColumnTypes(HibernateExtendedQuerySupport.java:246)
	at com.blazebit.persistence.impl.EntityMetamodelImpl.<init>(EntityMetamodelImpl.java:110)
	at com.blazebit.persistence.impl.CriteriaBuilderFactoryImpl.<init>(CriteriaBuilderFactoryImpl.java:81)
	at com.blazebit.persistence.impl.CriteriaBuilderConfigurationImpl.createCriteriaBuilderFactory(CriteriaBuilderConfigurationImpl.java:599)
	at com.pallasathenagroup.iris.producers.CriteriaBuilderFactoryProducer.init(CriteriaBuilderFactoryProducer.java:32)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.jboss.as.ee.component.ManagedReferenceLifecycleMethodInterceptor.processInvocation(ManagedReferenceLifecycleMethodInterceptor.java:96)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.doLifecycleInterception(Jsr299BindingsInterceptor.java:114)
	at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.processInvocation(Jsr299BindingsInterceptor.java:103)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:437)
	at org.jboss.weld.ejb.AbstractEJBRequestScopeActivationInterceptor.aroundInvoke(AbstractEJBRequestScopeActivationInterceptor.java:73)
	at org.jboss.as.weld.ejb.EjbRequestScopeActivationInterceptor.processInvocation(EjbRequestScopeActivationInterceptor.java:83)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.as.weld.injection.WeldInjectionInterceptor.processInvocation(WeldInjectionInterceptor.java:53)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.as.ee.component.ManagedReferenceFieldInjectionInterceptorFactory$ManagedReferenceFieldInjectionInterceptor.processInvocation(ManagedReferenceFieldInjectionInterceptorFactory.java:107)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.as.ee.component.AroundConstructInterceptorFactory$1.processInvocation(AroundConstructInterceptorFactory.java:28)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.as.weld.injection.WeldInterceptorInjectionInterceptor.processInvocation(WeldInterceptorInjectionInterceptor.java:56)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.as.weld.ejb.Jsr299BindingsCreateInterceptor.processInvocation(Jsr299BindingsCreateInterceptor.java:100)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.as.ee.component.NamespaceContextInterceptor.processInvocation(NamespaceContextInterceptor.java:50)
	at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
	at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:275)
	... 29 more

Expected behavior

Actual behavior

Steps to reproduce

Environment

Version: 1.2.0.Alpha3
JPA-Provider: Hibernate 5.2.12
DBMS: PostgresSQL
Application Server: Wildfly

[beikov]

Hmm, this seems like a bug that should be fixed. Have to investigate what is happening here exactly.
Implementing generate_series and table functions in general is going to require the use of the SQL from clause replacement mechanism since a table function will most probably have parameters.