[eclipselink-users] Re: [eclipselink-dev] @OneToMany with not nullable f

[Gordon Yorke <gordon.yorke@xxxxxxxxxx>]

Andrei,
    We are looking into the first issue but the easiest workaround for you is to map it as a bidirectional one to many
  With Item 2 you can register a DescriptorCustomizer for this Entity then on the descriptor's QueryManager set a custom join _expression_ using the outer join
   "ExpressionBuilder eb = new ExpressionBuilder();  descriptor.getQueryManager().setMultipleTableJoinExpression(eb.getField("EMP.ID").equalsOuterJoin(eb.getField("SECOND.FK")));"

--Gordon

Andrei Shakirin wrote:

Hi Gordon,

 

I am sorry to posting this into the dev list, but probably you can shortly help me with two following issues:

 

1.  @OneToMany with not nullable foreign key

I have a problem to use unidirectional OneToMany in case if foreign key in second table is not nullable.

 

Sample: Entities Transaction and Card are related as OneToMany

@Entity

@Table(name = "TRANS", schema="TEST")

public class TransactionType {

...

        @OneToMany(cascade = CascadeType.ALL)

        @JoinColumn(name="TRANS_ID")

        public java.util.Set<Card> getCards() {

                return cards;

        }

}

 

@Entity

@Table(name = "CARD", schema="TEST")

public class CardUseTypeJAXB {

…

}

 

The problem is that TRANS_ID column in CARD table is not nullable.

Eclipse Link generates three SQL statements:

1) INSERT INTO TEST.TRANS (URN, NAME) VALUES (?, ?)

     bind => [28, 0000001Z]

2) INSERT INTO TEST.CARD (URN, NUMBER) VALUES (?, ?)

  bind => [6, 12345]

3) UPDATE TEST.CARD SET TRANS_ID ? WHERE (URN = ?)

 

The third statements throws exception if TRANS_ID column is not nullable: Column 'TRANS_ID' doesn't accept Null value. (with nullable column all works fine).

Unfortunately I cannot change the DB schema.

Is there any way to solve this problem?

 

2. OUTER JOIN to Secondary Table

Use case: There is a main employee table that may or may not have some extra data populated in a related secondary table. If there is data in the secondary table (@SecondaryTable), then I would like my Employee entity to have those fields filled in. If there isn't data for a given employee in the secondary table, then I would like my Employee entity to have nulls in those fields. Right now, if there's no row in the secondary table for a given employee, I get nothing.

I cannot use OneToOne relation for this case, because mapping is defined directly for one business domain object.

 

Unfortunately I cannot find acceptable solution for it.
Is INNER JOIN for Secondary Table fixed by design?

 

Reagrds and thanks,

Andrei.

 

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