批更新从更新返回意外行数； 实际行数：0； 预期：使用NHibernate进行删除操作时为1

Question

I use NHibernate in c# and perform delete operation: My problem is that, When I login by 'A' user on 'PC1' and also login by same user on 'PC2' because I provide no. of session 2 for this user and delete one

record from 'PC1' record deleted successfully, But when same record delete from 'PC2' without refreshing page.then it gives exception as follows:

"Batch update returned unexpected row count from update; actual row count: 0; expected: 1"

here my code is :

public void Delete(object instance)
        {
            using(NHSession.BeginTransaction())
            {
                NHSession.Delete(instance);
                NHSession.Transaction.Commit();
            }
        }

here -

NHSession.Transaction.Commit(); this line gives error when I delete from 'PC2'. so here how to handle this problem using NHibernate. After executing this make sql query as follows:

DELETE FROM [Employee].[dbo].Employee_Master WHERE EmpID = @p0;@p0 = d3b9df34-97c6-450a-a570-a62000dd5125 [Type: Guid (0)]

and when same query execute in sql Studio then it return following o/p :

(0 row(s) affected)

Answer 1

It's caused by a weird way of coping with transactions or detached entities. When you avoid deleting detached entities directly, it doesn't happen.

I don't know why your transaction looks like this.

Either you should have started the transaction from some higher layer (never manage transactions from within the data access layer), or you get the object from the client directly and should load it as attached instance. In that case, you should only get the id from the client instead of the detached instance:

public void DeleteUserSession(Guid id)
{
    using(NHSession.BeginTransaction())
    {
      var instance = NHSession.Get(typeof(UserSession), id);
      if (instance != null)
      {
        NHSession.Delete(instance);
      }
      NHSession.Transaction.Commit();
    }
}