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I am trying to match the relationship for the first time. I have found many ways to go.

There are two classes: - Project (Parent) - Application (Child)

Thus, one project can have several applications, but one application belongs to only one project.

I built them as follows:

Project.java

 import javax.persistence.CascadeType;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.OneToMany;

    @Entity
    public class Project {

     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private int id;
        @OneToMany(cascade = CascadeType.ALL)
        @JoinColumn(name = "project_id", nullable=false)
        @org.hibernate.annotations.IndexColumn(name = "project_index")
        List<Application> applications = new ArrayList<Application>();

        [get and set methods...]
        }

Application.java

import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.ManyToOne;

    @Entity
    public class Application {

         @Id
         @GeneratedValue(strategy = GenerationType.IDENTITY)
         private int id;

            @ManyToOne
            @JoinColumn(name = "project_id", updatable = false, insertable = false, nullable=false)
            private Project project;

        [get and set methods...]
     }

... but, unfortunately, I got an exception that I cannot handle:

javax.servlet.ServletException: org.hibernate.PropertyValueException: not-null property references a null or transient value: ....common.entities.Application._applicationsBackref
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:321)
 org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:359)
 org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:275)
 org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
 org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
 org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:343)
 org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:272)
 org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:83)

root cause

javax.faces.el.EvaluationException: org.hibernate.PropertyValueException: not-null property references a null or transient value: ....common.entities.Application._applicationsBackref
 javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:98)
 com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:98)
 javax.faces.component.UICommand.broadcast(UICommand.java:311)
 javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:781)
 javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1246)
 com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:77)
 com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
 com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:114)
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:308)
 org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:359)
 org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:275)
 org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
 org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
 org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:343)
 org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:272)
 org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:83)

root cause

org.hibernate.PropertyValueException: not-null property references a null or transient value: ....common.entities.Application._applicationsBackref
 org.hibernate.engine.Nullability.checkNullability(Nullability.java:95)
 org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:313)
 org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
 org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
 org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
 org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56)
 org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
 org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50)
 org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)

Where is my mistake? I mean there is nothing. Project side only

When I remove @JoinColumn on the owner side, an exception is thrown:

java.sql.SQLException: Field 'project_id' doesn't have a default value

Thanks Pascal

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3 answers

There are several things fixed in your mapping.

  • , mappedBy "" ( , , ), , "" ( , , .. --).
  • @JoinColumn , .
  • JPA 2.0 Hibernate (.. Hibernate 3.5+), @OrderColumn Hibernate @IndexColumn
  • , @JoinColumn updatable = false, insertable = false, nullable=false, .

, ( JPA 2.0):

@Entity
public class Project {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @OneToMany(cascade = CascadeType.ALL, mappedBy="project")
    @OrderColumn(name = "project_index")
    List<Application> applications = new ArrayList<Application>();

    // getters, setters
}

@Entity
public class Application {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @ManyToOne
    @JoinColumn(name = "project_id")
    private Project project;

    // getters, setters
 }

, :

Project p = new Project();
Application a = new Application();
a.setProject(p);
p.getApplications().add(a);
em.persist(p);

, .

@Entity
public class Project {
    ...
    public void addToApplications(Application app) {
        this.applications.add(app);
        app.setProject(this);
    }
    ...
}

  • JPA 1.0
    • 2.1.8.2 " ManyToOne/OneToMany"
    • 9.1.24 "OneToMany Annotation"
    • 9.1.22 "ManyToOne Annotation"
  • JPA 2.0
    • 11.1.39 " "
+18

@JoinColumn . , .

, ,

@JoinColumn(name = "project_id", updatable = false, insertable = false, nullable=false)

. , , , , , , .

, @Column Id, Id.

+4

An object

@Table(name="Customer_v1")

@Inheritance(strategy = InheritanceType.SINGLE_TABLE)

@DiscriminatorColumn(name = "type", discriminatorType = DiscriminatorType.STRING)

public class Customer implements Serializable{                

                @Id

                @Column(name="cust_id")

                protected int custId;

 ------------------------------------------------

@Entity

@DiscriminatorValue(value = "N")

public class NewCustomer extends Customer {}

 

@Entity

@DiscriminatorValue( value="E")

public class ExistingCustomer extends Customer{}
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