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@AttributeOverride behavior

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eindh

Post subject: @AttributeOverride behavior

Posted: Fri Aug 27, 2010 1:57 pm

Newbie

Joined: Fri Aug 27, 2010 11:55 am
Posts: 2

Given these classes:

Code:

@Embeddable
public class E { ...
    @Column(nullable=false, precision=20, scale=6)
    private BigDecimal a;
}

@Entity
public class C { ...
    @AttributeOverride(name="a", column=@Column(name="b"))
    private E e;
}

What are the expected attributes for column "b"?

I thought I would get the new column name and the same nullable, precision and scale (false, 20, 6). But I got nullable=true, precision=19 and scale=2 (values which I don't know where they come). Not even a defaulted column with the new name.

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lukosan

Post subject: Re: @AttributeOverride behavior

Posted: Thu Jan 27, 2011 11:26 am

Newbie

Joined: Thu Jun 25, 2009 9:11 am
Posts: 1

The reason you get a numeric(19,2) is because these are the defaults implemented in org.hibernate.mapping.Column :-

Code:

   public static final int DEFAULT_LENGTH = 255;
   public static final int DEFAULT_PRECISION = 19;
   public static final int DEFAULT_SCALE = 2;

I've gotten around this by extending org.hibernate.dialect.PostgreSQLDialect :-

Code:

public class ImprovedPostgreSQLDialect extends PostgreSQLDialect {
   @Override
   public String getTypeName(int code, int length, int precision, int scale) throws HibernateException {
      if (Types.NUMERIC == code && precision == org.hibernate.mapping.Column.DEFAULT_PRECISION && 
            scale == org.hibernate.mapping.Column.DEFAULT_SCALE ) {
         return "numeric";
      }
      return super.getTypeName(code, length, precision, scale);
   }
}

which will return the more general "numeric" definition for the column instead of "numeric(19,2)". Note that this is not a perfect solution as you lose the ability to specify the precision in your database and instead rely on the face that you BigDecimal objects are set at the correct precision instead.

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