Annotations and use of PK problems

akhtara7 · **Joined:** Tue Jan 24, 2006 7:50 pm **Posts:** 11

Hi,
I am attempting to use annotations in my spring-hibernate application. I am having some difficulties with the primary key.

The problem is with the MyKey which represent the id of the object. The database field which is bankaccountID is of type int but i cant get it to retrieve the data, it fails with the following error.

Quote:

[JDBCExceptionReporter] Unknown column 'this_.primaryKey' in 'field list'

I have found that the problem is with

Code:

@Column(name = "BankAccountID")
   public MyKey getPrimaryKey() {
      return primaryKey;
   }

Changing it so it uses int works.

Code:

@Column(name = "BankAccountID")
   public Integer getPrimaryKey() {
      return primaryKey;
   }

I have enclosed the full code listing below.

The following is the Entity class

Code:

@SuppressWarnings("serial")
@Entity
@Table(name = "bankaccount")
public class BankTOAnonImpl implements Serializable {
   MyKey primaryKey;
   String description;
   Date transactionDate;

   public BankTOAnonImpl() {
   }

   @Column(name = "description")
   public String getDescription() {
      return description;
   }

   public void setDescription(String description) {
      this.description = description;
   }

   @Column(name = "transactionDate")
   public Date getTransactionDate() {
      return transactionDate;
   }

   public void setTransactionDate(Date transactionDate) {
      this.transactionDate = transactionDate;
   }

   [b]
        @Id
   @Column(name = "BankAccountID")
   public MyKey getPrimaryKey() {
      return primaryKey;
   }
        [/b]

   /**
    * @param primaryKey the primaryKey to set
    */
   public void setPrimaryKey(MyKey primaryKey) {
      this.primaryKey = primaryKey;
   }
}

The primary key object is defined as

Code:

@Embeddable
public class MyKey implements Serializable {
   private int primaryKey;

   /**
    * @return the primaryKey
    */
   public int getPrimaryKey() {
      return primaryKey;
   }

   /**
    * @param primaryKey the primaryKey to set
    */
   public void setPrimaryKey(int primaryKey) {
      this.primaryKey = primaryKey;
   }
}

The hibernate config file mapping is specified as

<mapping class="MyKey"/>
<mapping class="BankTOAnonImpl"/>

Thanks in advance

sanne.grinovero · **Posted:** Sun Sep 07, 2008 11:34 am

hi,
to use an embeddable object as PK you should use

Code:

@EmbeddedId

btw if you really only need an "int" in the embedded class, why not to use an Integer directly? Just wondering.

akhtara7 · **Joined:** Tue Jan 24, 2006 7:50 pm **Posts:** 11

Hi,
I have tried using EmbeddedId instead of Id, but got a different error

[JDBCExceptionReporter] Unknown column 'this_.primaryKey' in 'field list'

The actual field on the DB is BankAccountID but its called primaryKey on the java object.

The reason why we use an object to represent the key is because we may need to mask the key in future, it gives us more options to represent the key.

Thanks

sanne.grinovero · **Posted:** Sun Sep 07, 2008 11:53 am

I opened http://opensource.atlassian.com/projects/hibernate/browse/ANN-772
but I should have asked you which versions you are using.
Could you please tell me?

akhtara7 · **Joined:** Tue Jan 24, 2006 7:50 pm **Posts:** 11

I am using hibernate-annotations-3.4.0.GA and hibernate-3.2.6.ga

Thanks

akhtara7 · **Joined:** Tue Jan 24, 2006 7:50 pm **Posts:** 11

Good news, I have managed to figure it out.

Code:

@EmbeddedId
   @Column(name = "BankAccountID")
   @AttributeOverrides( {
      @AttributeOverride(name = "primaryKey", column = @Column(name = "BankAccountID"))
   })

The retreive at least is now working fine.

Thanks for your help

akhtara7 · **Joined:** Tue Jan 24, 2006 7:50 pm **Posts:** 11

A follow up on this, does hibernate annotations support interfaces. For example if I changed my Return type so it returns an interface for example

Code:

public IMyKey getPrimaryKey() {
      return primaryKey;
   } 

public interface IMyKey{
int getID();
void setID(int id);

}

I got an error

"Cannot instantiate abstract class or interface IMyKey "

sanne.grinovero · **Posted:** Tue Sep 09, 2008 7:51 pm

Hi,
yes of course, but you need to tell hibernate what to actually instantiate to set the value:

see

Code:

@Target

or

Code:

targetEntity

on the reference docs.

akhtara7 · **Joined:** Tue Jan 24, 2006 7:50 pm **Posts:** 11

Great, thats worked. I tried to use @Target before but it wouldn't work, turns out even though i downloaded the latest annotations my ide wasn't picking the jar up. I corrected this and now it works fine now

Thanks again