Question about embedded list of Strings

[Gul Onural <on...@nortel.com>]

Let say I have an entity MyEntity. The MyEntity has a list of strings
inside.

@Entity
@Table(name = "TABLE_A")
public class MyEntity implements Serializable {
      @Id
      private int myId;
      private String myName;
      private List<String> myList;
}

- How does openjpa stores instances of this class in the database? For
example does it create 
  one table and one record for each String in the myList ? 

- What would be the behavior of the openjpa if I put OneToMany
relationship annotation to the myList.
  I know what it does if the type of item in the list is a user-defined
class, but I don't know what happens if the items are Strings.

- What does openjpa do if I say this.myList = null; Does this remove all
the existing records ?

Thanks

Gul

Re: Question about embedded list of Strings

[Patrick Linskey <pl...@gmail.com>]

> - How does openjpa stores instances of this class in the database? For
> example does it create
>   one table and one record for each String in the myList ?

You could choose to store the entire List as a serialized BLOB, or to
store it as you described above using the @PersistentCollection
annotation.

> - What would be the behavior of the openjpa if I put OneToMany
> relationship annotation to the myList.
>   I know what it does if the type of item in the list is a user-defined
> class, but I don't know what happens if the items are Strings.

Good question. I'd expect an error, but I'm not sure.

> - What does openjpa do if I say this.myList = null; Does this remove all
> the existing records ?

You might want to turn on SQL debugging to take a look at what is
happening under the covers:

<property name="openjpa.Log" value="SQL=TRACE"/>

-Patrick

On Nov 6, 2007 8:47 AM, Gul Onural <on...@nortel.com> wrote:
>
>
> Let say I have an entity MyEntity. The MyEntity has a list of strings
> inside.
>
> @Entity
> @Table(name = "TABLE_A")
> public class MyEntity implements Serializable {
>       @Id
>       private int myId;
>       private String myName;
>       private List<String> myList;
> }
>
> - How does openjpa stores instances of this class in the database? For
> example does it create
>   one table and one record for each String in the myList ?
>
> - What would be the behavior of the openjpa if I put OneToMany
> relationship annotation to the myList.
>   I know what it does if the type of item in the list is a user-defined
> class, but I don't know what happens if the items are Strings.
>
> - What does openjpa do if I say this.myList = null; Does this remove all
> the existing records ?
>
> Thanks
>
> Gul
>
>
>
>
>
>



-- 
Patrick Linskey
202 669 5907