I am working on a web application that runs under Visual Studio 2005, language C#. I designed with Visual Paradigm the classes diagram and automatically generated the database and code with the VP tools.
The Perstent API type I used for code generation is “Static Methods”, I think is the most simple and ok for me.
I created a class called dao.cs so it contains every access to the database and connections. It looks like this:
public class dao
{
private PersistentManager persistenceManager = HMIPersistentManager.Instance();
private static dao instance = null;
private dao()
{
}
public static dao getInstance()
{
if (instance == null)
instance = new dao();
return instance;
}
public Recipe getRecipeByID(int id)
{
PersistentTransaction t = this.persistenceManager.GetSession().BeginTransaction();
Recipe a = Recipe.LoadRecipeByORMID(id);
t.Commit(); // <<-- exception here: already opened conexion or ID already in use....
return a;
}
/* more methods... */
}
The problem is, when executing the project, sometimes it throws an exception on the “t.Commit();” line. I would like to implement the best way for a web application: multiple users accessing the database, and everything running fine.
Do I need to use a lock like:
PersistentManager.instance().getSession().lock(obj, LockMode.NONE);
Where do I put it? Which lockmode choose?
Thanks in advance
