this problem is caused by Identity#equals noch checking objectsRealClass . consider the following situation: a select for InterfaceA fires 2 selects
SELECT A0.VALUE_,A0.ID FROM A_TABLE A0
retrieving Table_A objects with ids 1 and 2
SELECT A0.VALUE_,A0.ID FROM B_TABLE A0 INNER JOIN A_TABLE A1 ON A0.ID=A1.ID
retrieving Table_B object with id 1
when building the objects from the resultset in RsIterator#getObjectFromResultSet an identity is built from the row and looked up in the cache. the object (id = 1) from table_B is considered to be in the cache because the topLevelClass (InterfaceA) and the pk (1) matches !
this problem could be solved by also checking the objectsRealClass in Identity#equals. i remember there was quite a big discussion about Identity, so i'm not sure if this is a correct soluion ??
another solution could be to use a dedicated column to refer to the super-class in the reference-descriptor. this would avoid the pk-clash in the cache.
another way is to completly avoid using extents and super-references ;)
<class-descriptor class="polymorphtest.InterfaceA"> <extent-class class-ref="polymorphtest.A" /> <extent-class class-ref="polymorphtest.B" /> </class-descriptor>
<class-descriptor class="polymorphtest.A" table="A_TABLE">
<field-descriptor name="id" column="ID" jdbc-type="INTEGER" primarykey="true" autoincrement="true" />
<field-descriptor name="someValueFromA" column="VALUE_" jdbc-type="INTEGER" />
</class-descriptor>
<class-descriptor class="polymorphtest.B" table="B_TABLE">
<field-descriptor name="id" column="ID" jdbc-type="INTEGER" primarykey="true" autoincrement="true" />
<field-descriptor name="someValueFromB" column="VALUE_" jdbc-type="INTEGER" />
<reference-descriptor name="super" class-ref="polymorphtest.A">
<foreignkey field-ref="id" />
</reference-descriptor>
</class-descriptor>
jakob
Justis Peters wrote:
Hi All!
Just a couple weeks ago I started using OJB, and I am extremely impressed. My gratitude goes to all who put in the work to make it possible.
Upon converting some of the more complicated parts of my object model, I encountered a strange issue. Here is the bug I attempted to submit to scarab. Apparently, scarab is having problems. At first, it assigned an ID to my issue that was already assigned to another issue, so I can't retrieve it. Now, it won't let me enter new issues and keeps directing me to the query page isntead.
Anyhow, here is the summary of the bug. Any help would be appreciated:
========================================================================== When selecting an entire extent from a parent class, the behavior varies depending on whether you are using multi-table joins or distinct tables for each class. Everything seems to work correctly if you use distinct tables for each class. If you are using multi-table joins, however, your objects are not always materialized as the class you would expect. Here is the scenario for the test case I made:
Object model ------------ - public interface InterfaceA - public class A implements InterfaceA - public class B extends A implements InterfaceA
Test case 1 ----------- - start with a new JVM - select all from extent InterfaceA.class, loop through and display the class for each - select all from extent A.class, loop through and display the class for each - select all from extent B.class, loop through and display the class for each
Test case 2 ----------- - restart with a new JVM - select all from extent B.class, loop through and display the class for each - select all from extent A.class, loop through and display the class for each - select all from extent InterfaceA.class, loop through and display the class for each
Results ------- - If using distinct tables for each class (see schema1.sql and repository_user1.xml), both test cases materialize all objects as the correct subclass and returns the expected instances with the appropriate queries. - If using multi-table joins (see schema2.sql and repository_user2.xml), test case 1 displays everything as being class "A", even if it was a "B". Instances of "B" are retrieved and displayed twice in the queries for "InstanceA". Once you get to querying for "B", it turns up absolutely no instances. I imagine this is because it is cached. Test case 2 correctly materializes the objects a "B" and "A", depending on which table they appear in; when you query against InterfaceA.class, however, it still displays the duplicates for instances of "B".
For convenience in debugging, I have written a command-line test that lets you choose the order in which the extents are retrieved and displayed. You can run it by doing: java polymorphtest.PolymorphTest 0 1 2 (test case 1) OR java polymorphtest.PolymorphTest 2 1 0 (test case 2)
All the related classes, schemas, and O/R mappings are attached to this bug. Please contact me if you need help reproducing the errors.
================================================================
I don't want to send the attachments to the whole list, but I will be glad to email the tarball to whomever requests it. Thanks in advance for your help!
Sincerely, Justis Peters Oculan Corp. [EMAIL PROTECTED]
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