@OneToOne relationship with JPA

Question

I'm working on a project for my University. It's a booking system like AirBnb. Inside the system there are two entities: Request and Structure. A Structure cannot be inserted without a relative Request. So I modelled Request in this way:

public class Request {
      //...attributes (with a Generated Id)..//

      @OneToOne(optional=false)
      @JoinColumn(
        name="structure_id", unique=true, nullable=false, updatable=false)
      private Structure structure;
}

And Structure:

public class Structure{
      //...attributes (with a Generated Id)..//
     private Request request;

     @OneToOne(optional=false, mappedBy="structure")
     public Request getRequest() {
     return request;
}

Each time I try to test the application, it fails during

Persistence.createEntityManagerFactory()

with this error message:

Stacktrace:] with root cause org.hibernate.MappingException: Could not determine type for: it.ispw.efco.nottitranquille.model.Structure, at table: Request, for columns: [org.hibernate.mapping.Column(structure)] at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:396) at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:369) at org.hibernate.mapping.Property.isValid(Property.java:225) at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:529) at org.hibernate.mapping.RootClass.validate(RootClass.java:265) at org.hibernate.boot.internal.MetadataImpl.validate(MetadataImpl.java:329) at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:443) at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:879) at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:58) at javax.persistence.Persistence.createEntityMana gerFactory(Persistence.java:55) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39) at it.ispw.efco.nottitranquille.model.JPAInitializer.(JPAInitializer.java:25) at it.ispw.efco.nottitranquille.model.JPAInitializer.getEntityManager(JPAInitializer.java:43) at it.ispw.efco.nottitranquille.model.CatalogueDAO.saveRequest(CatalogueDAO.java:26) at it.ispw.efco.nottitranquille.view.SearchBean.validate(SearchBean.java:79) at org.apache.jsp.search_jsp._jspService(search_jsp.java:134) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340) at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilt er(ApplicationFilterChain.java:291) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) a t org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)

It's unable to map such relationship inside the DB? (MySQL 5.7.10 on Windows 10) Request cannot live without a Structure and viceversa. How can I solve it? Thank you very much in advance!

EDIT 1: I got this new error now:

org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : it.ispw.efco.nottitranquille.model.Structure.request -> it.ispw.efco.nottitranquille.model.Request

Is this code right? Request should save the structure linked to it, right?

    Address address = new Address(//some fields//);
    Structure structure = new Structure(/*a name*/,address);
    Request request = new Request(structure);
    CatalogueDAO catalogueDAO = new CatalogueDAO();
    catalogueDAO.saveRequest(request);

EDIT 2:

The previous problem is solved by adding (cascade = CascadeType.ALL) on the @OneToOne on Request.structure

But now I got this:

Cannot add or update a child row: a foreign key constraint fails ( notti_tranquille . request , CONSTRAINT FKbi1rasm9sdgrouh2mdklvi2q FOREIGN KEY ( id ) REFERENCES structure ( address_id ))

Structure has another attribute: Address, with its own Id and simple attributes

@OneToOne @MapsId
private Address address;

But If I check the tables created by JPA I see that the table structure has as primary key address_id... why?

Answer 1

Why is annotation above getRequest()? Try do this

public class Structure{
  //...attributes (with a Generated Id)..//
@OneToOne(optional=false, mappedBy="structure")
 private Request request;


 public Request getRequest() {
 return request;

}

Did you try to delete this annotation @JoinColumn( name="structure_id", unique=true, nullable=false, updatable=false) . Here you can find work example one to one example