composite-id with nullable columns?

dbtanner · **Joined:** Mon Jan 08, 2007 1:17 pm **Posts:** 2

I'm working with a flattened database view, where it doesn't have a good primary key design. It looks like this:
column A (not null)
column B (not null)
column C (nullable)

Where sometimes column C is used to identify between rows, and sometimes it's null, and it is assumed A and B are enough to uniquely identify a row.

e.g. You could have data like this:
A B C
1 1 1
1 1 2
1 2 null

The problem is, I'm not sure how to model my mapping.
If I model it so that column C is part of the composite-id, then that third row I get back in a query is completely null. e.g. The list.size() is 3, but only two of the elements are populated.
But if I just treat column C as a property of Foo and not part of FooId, then I only get two rows back in a query, and the data returned is a duplicate of row 1.

Am I missing something basic here, or is this type of mapping not currently allowed? TIA.

Here's what my mapping looks like:

Code:

<hibernate-mapping>
  <class name="Foo" table="foo">
    <composite-id name="id" class="FooId">
      <key-property name="a" type="java.lang.String" column="a"/>
      <key-property name="b" type="java.lang.String" column="b"/>
      <key-property name="c" type="java.lang.String" column="c"/>
    </composite-id>
    <property name="d" type="java.lang.String" column="d"/>
    <property name="e" type="java.lang.String" column="e"/>
  </class>
</hibernate-mapping>


public class Foo implements Serializable {
    private FooId;
    private String d;
    private String e;
}


public class FooId implements Serializable {
    private String a;
    private String b;
    private String c;
    

    // implemented equals and hashcode, allowing for c to be null
    
}

BrendanKim · **Posted:** Mon Jan 08, 2007 3:24 pm

Hopefully CompositeUserType will give you a good and stable solution.

kochcp · **Posted:** Mon Jan 08, 2007 3:45 pm

I don't think hibernate will elt you have a null member of a composite key. You could try a CustomUserType like the above guy said and change it to something for use in hibernate but I'm not sure how early hibernate checks for good data.