JDOQL queryfilter failure while retrieving field of "java.lang.Object" Type.

Question

PROBLEM DESCRIPTION --->
JDOQL FILTER ON A FIELD OF "java.lang.Object" TYPE, NOT WORKING.
HELP REQUESTED WITH SUGGESTIONS OR POINTERS TO THE CORRECT SOLUTION.
Deatiled Problem :=
Environment :=
Kodo version 2.4.1 (on Windows 2000).
J2SDK 1.3.1_06 (on Windows 2000).
Database:= MySQL 3.23.55 (on Windows 2000).
Java Class Hierarchy Example:=
SuperPersistentObject
|__ LevelOneDescendant
|__ LevelTwoDescendant
|__ LastDescendant
Procedures Followed :=
Java class named "LastDescendant" is enhanced and persisted in the
database.
The field "m_value" is of java type "java.lang.Object" and is
represented as a "blob" in the database.
Aadequate data is pumped in the field "m_value" (Data of Type
String/Integer/Double/Boolean etc.). The class "LastDescendant" is
retrieved using following JDO specific code :=
SUCCESSFUL EXAMPLE :=
Extent extent= PersistentManager.getExtent
(com.name.project.LastDescendant.class, false);
String m_queryFilter = "";
Query query = PersistentManager.getQuery(extent, m_queryFilter);
Collection m_resultset = (Collection)query.execute();
The above code returns all the available "LastDescendant" objects
persisted in the DB. Post Load, The value in the field "m_value" of
all the retrieved "LastDescendant" objects, is testeded successfully
and found to be matching to the expected values.
FAILED EXAMPLE :=
Extent extent= PersistentManager.getExtent
(com.name.project.LastDescendant.class, false);
//Retrieving only the objects whose "m_value" field contains Integer
// values, between 10 and 9000. (110 objects with Integer value
// between 10 and 9000 are pumped in the DB, for testing).
String m_queryFilter = "(m_value >= 10 && m_value <= 9000)";
Query query = PersistentManager.getQuery(extent, m_queryFilter);
Collection m_resultset = (Collection)query.execute();
NO "LastDescendant" OBJECTS RETRIEVED, the Collection "m_resultset" is
Empty, (Actually Expecting 110 objects).
Tried every other way, using "declareImports()"/ "declareParameters()"/
"declareVariables()" etc. Tried TypeCasting the m_value field to Integer,
but to no avail.
Actual Classes :=
public class SuperPersistentObject implements java.io.Serializable {
protected String appKey;
public class LevelOneDescendant extends SuperPersistentObject {
protected SuperPersistentObject m_classRef;
public class LevelTwoDescendant extends LevelOneDescendant {
protected Object m_value;
public class LastDescendant extends LevelTwoDescendant {
"project.jdo" meta-data entry :=
<class name="SuperPersistentObject"
identity-type="application"
objectid-class="com.name.project.AppKeyImpl">
<field name="appKey" primary-key="true"/>
</class>
<class name="LevelOneDescendant" identity-type="application"
persistence-capable-superclass =
"com.name.project.SuperPersistentObject">
</class>
<class name="LevelTwoDescendant" identity-type="application"
persistence-capable-superclass =
"com.name.project.LevelOneDescendant">
<field name="m_value">
<extension vendor-name="kodo" key="data-column" value="VALUE"/>
</field>
</class>
<class name="LastDescendant" identity-type="application"
persistence-capable-superclass="com.name.project.LevelTwoDescendant">
</class>
JDO related properties :=
javax.jdo.PersistenceManagerFactoryClass =
com.solarmetric.kodo.impl.jdbc.JDBCPersistenceManagerFactory
javax.jdo.option.ConnectionURL= jdbc:mysql://localhost/PRTestDB
javax.jdo.option.ConnectionUserName= SuperUser
javax.jdo.option.ConnectionPassword= <xxxxxx>
javax.jdo.option.ConnectionDriverName= com.mysql.jdbc.Driver
javax.jdo.option.Optimistic= true
javax.jdo.option.RetainValues= true
javax.jdo.option.NontransactionalRead= true
javax.jdo.option.NontransactionalWrite= true
javax.jdo.option.RestoreValues= true
javax.jdo.option.Multithreaded= true
javax.jdo.option.MsWait= 5000
javax.jdo.option.IgnoreCache= false
javax.jdo.option.MinPool= 1
javax.jdo.option.MaxPool= 80
com.solarmetric.kodo.impl.jdbc.WarnOnPersistentTypeFailure= true
com.solarmetric.kodo.impl.jdbc.SequenceFactoryClass=
com.solarmetric.kodo.impl.jdbc.schema.DBSequenceFactory
com.solarmetric.kodo.impl.jdbc.FlatInheritanceMapping= true
com.solarmetric.kodo.LicenseKey= <xxxx-yyyy-zzzz-2345-6789>
com.solarmetric.kodo.EnableQueryExtensions= false
com.solarmetric.kodo.DefaultFetchThreshold= 30
com.solarmetric.kodo.DefaultFetchBatchSize= 10

Answer 1

You can't query on a blob column.