Seam-gen and

[masotime]

Hi,

I'm currently using Seam 2.1.2.GA on JBoss 5.1.0.GA.  I am new to Seam, and am trying out a simple example via the use of seam-gen.  My seam setup is configured to deploy to a WAR, using MySQL as a database, with RichFaces components for JSF.

I have 2 entity beans I coded by hand, which form a simple master-detail relationship:

@Entity
@Name("fruitFamily")
public class FruitFamily {

  @Id @GeneratedValue
  private Long id;
  
  @Version
  private Long version;
  
  @NotNull
  private String name;
  
  @OneToMany(mappedBy="fruitFamily")
  private Set<Fruit> fruits;

  // getters and setters as generated by Eclipse
    
}

@Entity
@Name("fruit")
public class Fruit {
  
  @Id @GeneratedValue
  private Long id;
  
  @Version
  private Long version;
  
  @NotNull @Length(max=100)
  private String name;
  
  @NotNull
  private Boolean poisonous;
  
  @ManyToOne
  private FruitFamily fruitFamily;  

  // getters and setters generated by Eclipse

}

After writing these classes, I ran seam generate-ui and decided to give the generated CRUDs a spin.  However, when I try to create a FruitFamily I get an exception in the xhtml page:

javax.el.ELException: /FruitFamilyEdit.xhtml @79,68 rendered="#{empty fruitFamilyHome.fruits}": Error reading 'fruits' on type FruitFamilyHome_$$_javassist_seam_4

My understanding is that adding the mappedBy clause to the @OneToMany annotation causes seam-gen to create jsf codes to display the list of child objects associated with the parent object.  If I remove the clause, I do not get this exception.

I am not sure how to proceed at this point.  Am I making a mistake in how I code my Entity classes?  Is there a better approach to how I'm doing things?

Thanks in advance.

[masotime]

Gah... sorry about the title.  I meant to name it something like Difficulties with Seam-gen and master-detail relationships.

[masotime]

Nevermind.  I believe I have figured it out.  I tried doing it in reverse, using generate-model to generate the Entity beans, and I discovered that the line

@OneToMany(mappedBy="fruitFamily")
  private Set<Fruit> fruits;

was slightly different from the one generated by seam-gen.  In particular, the set had a default initialized value rather than being null.

private Set<Fruit> fruits = new HashSet<Fruit>();

This seemed to solve the problem.