Mapping Set<enum> using @ElementCollection

Question

I have the following enum:

package ir.raysis.tcs.rule.days;

public enum Days {
    SUNDAY, MONDAY, TUESDAY, WEDNESDAY,
    THURSDAY, FRIDAY, SATURDAY;
}

I tried to map it as a Set<Days> days as follows:

@ElementCollection(targetClass = Days.class) 
@JoinTable(name = "days",joinColumns = @JoinColumn(name = "rule_id")) 
@Column(name ="daysOfWeek", nullable = false) @Enumerated(EnumType.STRING) 
private Set<Days> days = new HashSet<>();

However, it throws the following exception:

Initial SessionFactory creation failed.org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: rule, for columns: [org.hibernate.mapping.Column(days)]
Apr 14, 2013 4:15:17 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path [/ptcs] threw exception [javax.servlet.ServletException: java.lang.ExceptionInInitializerError] with root cause
org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: rule, for columns: [org.hibernate.mapping.Column(days)]
    at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:306)
    at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:290)
    at org.hibernate.mapping.Property.isValid(Property.java:217)
    at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:464)
    at org.hibernate.mapping.RootClass.validate(RootClass.java:235)
    at org.hibernate.cfg.Configuration.validate(Configuration.java:1362)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1865)
    at ir.raysis.tcs.db.HibernateUtil.<clinit>(HibernateUtil.java:18)
    at ir.raysis.tcs.db.SaveUpadteDelete.save(SaveUpadteDelete.java:33)
    at ir.raysis.tcs.db.dBAllFunc.save(dBAllFunc.java:35)
    at ir.raysis.tcs.db.AbsDBObject.save(AbsDBObject.java:45)
    at ir.raysis.tcs.action.CreateMemberAction.execute(CreateMemberAction.java:31)
    at org.apache.jsp.action.createMember_jsp._jspService(createMember_jsp.java:79)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1770)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

How do I properly map it?

Answer 1

for future googlers! finally i managed to solve the problem, i just had to put the annotations somewhere else in my code ,

@ElementCollection(targetClass = Days.class)
@CollectionTable(name = "days", joinColumns = @JoinColumn(name = "rule_id"))
@Column(name = "daysOfWeek", nullable = false)
@Enumerated(EnumType.STRING)
public Set<Days> getDays() {
    return days;
}

as you can see i wrote the annotation code above and before the getter method(instead of placing it before the attribute declaration code) and problem solved, anyone who can explain me what causes this will be appreciated. thank you

Answer 2

Try using @CollectionTable and not @JoinTable

Answer 3

While the other question is correct, the most simple form could be:

@ElementCollection
@Enumerated
private Set<EnumName> enumValues;

everything else would be set by convention over configuration (join-table-name, columns).

I highly recommend using @Enumerated(EnumType.STRING) - look it up why. And you might need @ElementCollection(fetch = FetchType.EAGER) depending on what (and where) you're doing.