Hi ,
I am getting ClassCastException whenever i try to save one of my Object.

I have checked my Database tables , Classes Definition as well as mapping definition all have similar "types" for all the properties/columns still it is giving this exception .

I checked the log created at server it is also generating the right queries and binding with correct type , still it is failing somewhere .
I'd be very thanful if anyone can tell me where it is failing and how to correct it .

About my Code --

A simple program that has Student Class and Course Classmapped with Student table and Course Table Respectively .

A student can belong to many courses so a table student_course has been made for this association .

I am using Hibernate3 and JBoss AS .

Please help me !!!

Following is the code that is failing-(raising exception on tx.commit();)

Student student = new Student();
student.setFirstName(request.getParameter("firstName"));
student.setLastName(request.getParameter("lastName"));
//student.setDob(null);
student.setAddress(request.getParameter("address"));
String[] courses = request.getParameterValues("courses");
HashSet coursesForStudent = new HashSet();
for(int i = 0 ; i < courses.length; i++)
{

Course course = (Course) session.load(Course.class, courses[i]);
coursesForStudent.add(course) ;
}
student.setCourses(coursesForStudent) ;
session.save(student);
//sessiongetTransaction().commit();
tx.commit(); // Faling on this line

Following is the part of Log generated at server here the biding types are shown correctly as org.hibernate.type.LongType ---
------------------------------------
2007-06-26 20:14:43,504 DEBUG [org.hibernate.jdbc.AbstractBatcher] closing statement
2007-06-26 20:14:43,504 DEBUG [org.hibernate.persister.collection.AbstractCollectionPersister] Inserting collection: [sis.Student.courses#34]
2007-06-26 20:14:43,504 DEBUG [org.hibernate.jdbc.AbstractBatcher] about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
2007-06-26 20:14:43,504 DEBUG [org.hibernate.SQL] insert into STUDENT_COURSE (STUDENTROLLNO, COURSEID) values (?, ?)
2007-06-26 20:14:43,504 INFO [STDOUT] Hibernate: insert into STUDENT_COURSE (STUDENTROLLNO, COURSEID) values (?, ?)
2007-06-26 20:14:43,504 DEBUG [org.hibernate.jdbc.AbstractBatcher] preparing statement
2007-06-26 20:14:43,504 DEBUG [org.hibernate.type.LongType] binding '34' to parameter: 1
2007-06-26 20:14:43,504 DEBUG [org.hibernate.type.LongType] binding '1' to parameter: 2
2007-06-26 20:14:43,504 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/BankManagementWeb].[StudentManager]] Servlet.service() for servlet StudentManager threw exception
java.lang.ClassCastException: java.lang.String
at org.hibernate.type.LongType.set(LongType.java:40)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:62)
-------------------------------------------------------------------------



Following is the mapping for the object that i am trying to save ---

<hibernate-mapping>
<class name="sis.Student" table="Student">
<id name="rollNo" column="rollNo" type="long">
<generator class="sequence">
<param name="sequence">student_rollNo_sequence</param>
</generator>
</id>

<property name="firstName"/>
<property name="lastName"/>
<property name="dob" type="date"/>
<property name="address" />

<set name="courses" table="STUDENT_COURSE">
<key column="STUDENTROLLNO"/>
<many-to-many column="COURSEID" class="sis.Course" />
</set>
</class>
</hibernate-mapping>

Following is the mapping for Course Class --

<hibernate-mapping>

<class name="sis.Course" table="Course">
<id name="id" column="id" type="long">
<generator class="sequence">
<param name="sequence">course_id_sequence</param>
</generator>
</id>

<property name="name"/>
</class>

</hibernate-mapping>

Thanks in advance for your help .

Best Regards ,
Chandan Ahuja

What is your db sequence type? It seems like those sequences are string typed although your ids are long ones. Maybe try changing those sequence to long or changing the id types.