[Hibernate-issues] [Hibernate-JIRA] Commented: (HB-208) ArrayIndexOutOfBoundsException is thrown when an attempt is make to save a polymorphic object (with discriminator column)

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The following comment has been added to this issue:

     Author: Ferdinand Che
    Created: Tue, 22 Jul 2003 8:15 AM
       Body:
An alternative solution would be not to include the discriminator column in the list of properties. Presently the property associated with the dicriminator column also has to be included as a property in the mappings file - otherwise, it is not possible to handle this field as a persistent field/property.
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View the issue:

  http://opensource.atlassian.com/projects/hibernate/secure/ViewIssue.jspa?key=HB-208


Here is an overview of the issue:
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        Key: HB-208
    Summary: ArrayIndexOutOfBoundsException is thrown when an attempt is make to save a polymorphic object (with discriminator column)
       Type: Bug

     Status: Unassigned
   Priority: Critical

    Project: Hibernate2
 Components: 
             core
   Versions:
             2.0.2

   Assignee: 
   Reporter: Ferdinand Che

    Created: Tue, 22 Jul 2003 8:03 AM
    Updated: Tue, 22 Jul 2003 8:03 AM
Environment: XP, JBoss-3.2.1, JDK-1.4.1_02,MySQL-4.0.12-max-nt

Description:
An ArrayIndexOutOfBoundsException is thrown when an attempt is made to save (e.g. session.save(obj);session.flush();) that is a subclass (see mapping extract below). This exception is thrown at the point where the underlying preparedstatement is being populated with data following a net.sf.hibernate.type.StringType.set()-->line 22; following a call to EntityPersister.dehydrate() folowing an EntityPersister.insert().

On further inspection I have been able to determine that this is caused by a line in EntityPersister.generateInsertString() --> specifically: insert.addColumn(getDiscriminatorColumnName(), discriminatorSQLString); This line is only called because in this scenario we are handling polymorphic behaviour. the trouble is that this conflicts with the other underlying handling of object properties. The above call effectively overrides what what should appear in the resultant sql from something like (... (?,?,?,?) to an sql containing something like (?,?,'2',?). The trouble is then that when it comes to populating the prepared statement the there is one index more than is required and 'bang' ... an ArrayIndexOutOfBoundsException is thrown.

This can be 'fixed' by completely removing the line: insert.addColumn(getDiscriminatorColumnName(), discriminatorSQLString); and of cause the if statement associated with it Or making sure that the Property.isInsertable() returns false for all discriminator columns. I have used the former as a temporary fix until I get further feedback from the hibernate people.

The following is an example extract from mapping file that will trigger this issue:
<class name="com.mycom.data.ITestItem table="ITEMS">
    <id name="code" column="CODE" type="string" unsaved-value="any">
       <generator class="assigned">
       </generator>
    </id>
    <discriminator column="TYPE" type="string" />
    <property name="name" type="java.lang.String" column="NAME" not-null="true" />
    <property name="desc" type="java.lang.String" column="DESCR" not-null="true" />
    <property name="type" type="int" column="TYPE" not-null="true" />
    <subclass name="com.mycom.data.TestItemType1" discriminator-value="1" />
    <subclass name="com.mycom.data.TestItemType2" discriminator-value="2" />
</class>


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