NHibernate Repository pattern problem - nhibernate

Question

I am using NHibernate and Repository patterns in my application. But not want to use UnitofWork pattern.
There are two types of forms in my app. Collection/Picker forms and Entity forms.
But the problem occurs when a form is ShowDialog()ged from within another form.
Whwn I am doing any database related operation, NHibernate is giving me "a different object with the same identifier value was already associated with the session: XYZ" error. This is caused due to the delayed call of Dispose method by CLR and another part of my problem is in the Session management as far as I guess.
How can I change my repository codes to solve my problem?
Remember, I don't want to expose separate BeginTransaction(), CommitTransaction() like functions in my Repository. These things should be embedded within every Method {SaveOrUpdate(), Save(), Delete, Load(), etc.} as I have already done.
Please tell me how can I get things going with minor changes?
I am doing my things like this:
A picker form works like this,
private void btnPick_Click(object sender, EventArgs e)
{
CourseCollectionForm f = new CourseCollectionForm();
f.FormViewMode = FormViewMode.MultiplePicker;
f.ShowDialog();
int totalCredits = 0;
int totalHours = 0;
FillDataGridViewWithCourses(f.PickedCourseCollection, ref totalCredits, ref totalHours);
FillTotal(totalCredits, totalHours);
}
A Save works like this,
public partial class DepartmentEntityForm : Form
{
private DepartmentRepository _deptRepository = null;
private Department _currentDepartment = null;
private FormViewMode _currentMode = FormViewMode.None;
public DepartmentEntityForm(Department dept, FormViewMode mode)
{
InitializeComponent();
_deptRepository = new DepartmentRepository();
_currentDepartment = dept;
_currentMode = mode;
if(mode == FormViewMode.Edit)
{
MapObjectToControls();
}
}
private void SaveButton_Click(object sender, EventArgs e)
{
Department newDept;
if (mode == FormViewMode.AddNew)
{
newDept = new Department();
}
else if(mode == FormViewMode.Edit)
{
newDept = _currentDepartment;
}
//.............
//.............
_deptRepository.SaveOrUpdate(newDept);
}
}
I declare my individual repositories like this:
FacultyRepository.cs
public class FacultyRepository : Repository<Faculty>
{
}
DepartmentRepository.cs
public class DepartmentRepository : Repository<Department>
{
}
Repository.cs
public class Repository<T> : IRepository<T>
{
ISession _session;
public Repository()
{
_session = SessionFactory.GetOpenSession();
}
public T Get(object id)
{
T obj = default(T);
try
{
if (!_session.Transaction.IsActive)
{
_session.BeginTransaction();
obj = (T)_session.Get<T>(id);
_session.Transaction.Commit();
_session.Flush();
}
else
{
throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
}
}
catch (Exception ex)
{
_session.Transaction.Rollback();
_session.Clear();
throw ex;
}
return obj;
}
public IEnumerable<T> Get(string fieldName, object fieldValue)
{
IEnumerable<T> list = null;
try
{
if (!_session.Transaction.IsActive)
{
_session.BeginTransaction();
list = (IEnumerable<T>)_session.CreateCriteria(typeof(T))
.Add(new NHibernate.Expression.EqExpression(fieldName, fieldValue))
.List<T>();
_session.Transaction.Commit();
_session.Flush();
}
else
{
throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
}
}
catch (Exception ex)
{
_session.Transaction.Rollback();
_session.Clear();
throw ex;
}
return list;
}
public IEnumerable<T> Get()
{
IEnumerable<T> list = null;
try
{
if (!_session.Transaction.IsActive)
{
_session.BeginTransaction();
list = (IEnumerable<T>)_session.CreateCriteria(typeof(T)).List<T>();
_session.Transaction.Commit();
_session.Flush();
}
else
{
throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
}
}
catch (Exception ex)
{
_session.Transaction.Rollback();
_session.Clear();
throw ex;
}
return list;
}
public void SaveOrUpdate(T obj)
{
try
{
if (!_session.Transaction.IsActive)
{
_session.BeginTransaction();
_session.SaveOrUpdateCopy(obj);
_session.Transaction.Commit();
_session.Flush();
}
else
{
throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
}
}
catch (Exception ex)
{
_session.Transaction.Rollback();
_session.Clear();
throw ex;
}
}
public void SaveOrUpdate(IEnumerable<T> objs)
{
try
{
if (!_session.Transaction.IsActive)
{
_session.BeginTransaction();
foreach (T obj in objs)
{
_session.SaveOrUpdate(obj);
}
_session.Transaction.Commit();
_session.Flush();
}
else
{
throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
}
}
catch (Exception ex)
{
_session.Transaction.Rollback();
_session.Clear();
throw ex;
}
}
public void Delete(T obj)
{
try
{
if (!_session.Transaction.IsActive)
{
_session.BeginTransaction();
_session.Delete(obj);
_session.Transaction.Commit();
_session.Flush();
}
else
{
throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
}
}
catch (Exception ex)
{
_session.Transaction.Rollback();
_session.Clear();
throw ex;
}
}
public void Delete(IEnumerable<T> objs)
{
try
{
if (!_session.Transaction.IsActive)
{
_session.BeginTransaction();
foreach (T obj in objs)
{
_session.Delete(obj);
}
_session.Transaction.Commit();
_session.Flush();
}
else
{
throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
}
}
catch (Exception ex)
{
_session.Transaction.Rollback();
_session.Clear();
throw ex;
}
}
public void DeleteAll()
{
try
{
if (!_session.Transaction.IsActive)
{
_session.BeginTransaction();
DetachedCriteria criterion = DetachedCriteria.For<T>();
IList<T> list = criterion.GetExecutableCriteria(_session).List<T>();
foreach (T item in list)
{
_session.Delete(item);
}
_session.Transaction.Commit();
_session.Flush();
}
else
{
throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
}
}
catch (Exception ex)
{
_session.Transaction.Rollback();
throw ex;
}
}
public void Dispose()
{
if (_session != null)
{
_session.Clear();
_session.Close();
_session = null;
}
}
}
SessionFactory.cs
public class SessionFactory
{
private static ISessionFactory _sessionFactory = null;
private SessionFactory(){}
static SessionFactory()
{
if (_sessionFactory == null)
{
Configuration configuration = new Configuration();
configuration.Configure();
_sessionFactory = configuration.BuildSessionFactory();
}
}
public static ISession GetOpenSession()
{
return _sessionFactory.OpenSession();
}
}

Answer 1

OK guys! It has been long since I posted my question and nobody tends to answer it.
I solved it by making ISession static in the SessionFactory and instead of returning a Open ISession for each Repository, I am returning only one static ISession.