I am trying to use NHibernate in my project, i am getting the following error
"Initializing[BO.Job#34543]-failed to lazily initialize a collection of role: BO.Job.bInterview, no session or session was closed". can someone help me.
public HttpResponseMessage GetbyId(int Id)
{
Job job = new Job();
try
{
using (ISession session = NHibernateSession.OpenSession()) // Open a session to conect to the database
{
// books = session.Query<Book>().ToList(); // Querying to get all the jobs
JobRepo = new Repo<Job>(session);
job = JobRepo.GetById(Id, "Job_selectbyId");
}
return Request.CreateResponse(HttpStatusCode.OK, job);
}
catch (Exception exp)
{
Log.Error(exp);
return Request.CreateResponse(HttpStatusCode.ExpectationFailed, job);
}
}
public T GetById(int id,string SPName)
{
T result;
//return await Task.Run(() =>
//{
IQuery query = _session.GetNamedQuery(SPName);
query.SetParameter("job_id", id);
//book = _session.Query<Book>().Where(b => b.Id == id).FirstOrDefault();
result = query.UniqueResult<T>();
return result;
//});
}
This is probably because you're trying to access a property that's been marked as 'lazy' after the session has been closed.
My guess is that you're returning job and then the session is being disposed. Some other code is then attempting to access the Interview property of the returned job, which needs to session to implement the lazy loading feature but the session's been disposed.
You can change you query so that Interview is 'pre-fetched' or you can change your mapping so that there's no lazy initialisation on the class or the property.
Related
I am getting following error when accessing HttpContext.Session from static method placed in separate task:
Session has not been configured for this application or request.
I used this article to implement access to HttpContext outside the controller
From controller I invoke this static method that used to retrieve image data:
public static void CreateDummyGallery(Gallery gallery)
{
Logger.LogDebug(LogModule.Dummy, $"Starting gallery creation.");
Task.Factory.StartNew(() =>
{
try
{
List<DummyPicture> pictures;
using (var context = new MyzeumContext())
{
int top = 10;
pictures = context.DummyPictures.FromSql($"SELECT * FROM dummypictures ORDER BY RAND() LIMIT {top}").ToList();
}
Logger.LogDebug(LogModule.Dummy, $"Starting retrieving images.");
Parallel.ForEach(pictures, picture => {
using (WebClient client = new WebClient())
{
}
});
Logger.LogDebug(LogModule.Dummy, $"Done retrieving images.");
}
catch(Exception e)
{
Logger.LogError(LogModule.Server, e.Message, e);
}
});
}
The problem occurs in Logger.LogDebug() because this is where I access HttpContext:
public void LogDebug(LogModule module, string message, Exception stackTrace = null)
{
Log record = new Log();
record.Module = module;
record.ThreadId = Environment.CurrentManagedThreadId;
record.SessionId = HttpContextHelper.Current?.Session?.Id;
record.Message = message;
record.Logged = DateTime.UtcNow;
if(stackTrace != null)
{
record.Message += $" :{stackTrace.StackTrace}";
}
queue.Enqueue(record);
}
The problem 99% occurs in the first call inside task:
Logger.LogDebug(LogModule.Dummy, $"Starting retrieving images.");
BUT, right after application starts this whole task block works fine and does not throw any exception. Problem starts after following requests.
Connected to website and keeping idle for 30 mins, then trying to access the entities I am getting the following error.
Entity framework An error occurred while executing the command definition. See the inner exception for details . Inner exception {“Invalid object name 'dbo.TableName'.”}
Sample Code
Static Class Azure
{
public static CrmEntities ConnectCustomerEntity()
{
CrmEntities customerEntity = null;
policy.ExecuteAction(() =>
{
try
{
var shardId = GetShardId();
customerEntity = new CrmEntities(ConnectionStringCustomerDB());
string federationCmdText = #"USE FEDERATION Customer_Federation(ShardId =" + shardId + ") WITH RESET, FILTERING=ON";
customerEntity.Connection.Open();
customerEntity.ExecuteStoreCommand(federationCmdText);
}
catch (Exception e)
{
customerEntity.Connection.Close();
SqlConnection.ClearAllPools();
//throw e;
}
});
return customerEntity;
}
public static CrmEntities DBConnect(CrmEntities _db)
{
try{
if (_db == null)
_db = Azure.ConnectCustomerEntity();
if ((_db.Connection.State == ConnectionState.Broken) || (_db.Connection.State == ConnectionState.Closed))
{
SqlConnection.ClearAllPools();
_db = Azure.ConnectCustomerEntity();
}
else
{ //This code is to find out any issues in connection pool database connection
string sqlCmdText = #"select top 1 Id from Project";
_db.ExecuteStoreCommand(sqlCmdText);
}
}
catch (Exception ex)
{
_db.Connection.Close();
SqlConnection.ClearAllPools();
_db = Azure.ConnectCustomerEntity();
}
return _db;
}
}
Mvc Controller. The following code I am gettting that exception, after 30 mins
public class FilterController : Controller
{
public ActionResult GetFilters(string entityName,string typeFilter)
{
_crmEntities=Azure.DBConnect(_db);
var query = _db.FilterFields.Where(filter => filter.TableId == tableId).ToList(); // Here I am getting that exception
}
}
I dont know, Why i m getting that exception. I tried all possibilities. Nothing helped. I really struck with this. If anybody knows please tell your views to come out from this exception
Thanks in Advance.
I think your session times out.
try to increase session timeout:
http://msdn.microsoft.com/en-us/library/system.web.sessionstate.httpsessionstate.timeout.aspx
I am trying out the WCF Transaction implementation and I come up with the idea that whether asynchronous transaction is supported by WCF 4.0.
for example,
I have several service operations with client\service transaction enabled, in the client side, I use a TransactionScope and within the transaction, I create Tasks to asynchronously call those operations.
In this situation, I am assuming that the transaction is going to work correctly, is that right?
I doubt that very much. It appears that you if you are starting an ascync operation you are no longer participating on the original transaction.
I wrote a little LINQPad test
void Main()
{
using (var scope = new TransactionScope(TransactionScopeOption.Required))
{
try
{
Transaction.Current.Dump("created");
Task.Factory.StartNew(Test);
scope.Complete();
}
catch (Exception e)
{
Console.WriteLine(e);
}
Thread.Sleep(1000);
}
Console.WriteLine("closed");
Thread.Sleep(5000);
}
public void Test()
{
using (var scope = new TransactionScope(TransactionScopeOption.Required))
{
Transaction.Current.Dump("test start"); // null
Thread.Sleep(5000);
Console.WriteLine("done");
Transaction.Current.Dump("test end"); // null
}
}
You'll need to set both the OperationContext and Transaction.Current in the created Task.
More specifically, in the service you'll need to do like this:
public Task ServiceMethod() {
OperationContext context = OperationContext.Current;
Transaction transaction = Transaction.Current;
return Task.Factory.StartNew(() => {
OperationContext.Current = context;
Transaction.Current = transaction;
// your code, doing awesome stuff
}
}
This gets repetitive as you might suspect, so I'd recommend writing a helper for it.
I am trying to use TransactionScope with NHibernate in order to call several methods in one transactions. Data repository methods are like this:
public virtual void Save(T dataObject)
{
try
{
using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions { IsolationLevel = IsolationLevel.RepeatableRead }))
{
this.session.SaveOrUpdate(dataObject);
scope.Complete();
}
}
catch (Exception ex)
{
bool rethrow = ExceptionPolicy.HandleException(ex, "Data Layer Policy");
if (rethrow)
{
throw;
}
}
}
public T GetByNumber(string documentNumber)
{
T document = null;
try
{
using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions { IsolationLevel = IsolationLevel.RepeatableRead }))
{
document = this.Session.CreateCriteria(typeof(T))
.Add(Restrictions.Eq("Number", documentNumber))
.UniqueResult();
scope.Complete();
}
}
catch (Exception ex)
{
bool rethrow = ExceptionPolicy.HandleException(ex, "Data Layer Policy");
if (rethrow)
{
throw;
}
}
return document;
}
I wanted to test row/table locking in transactions so I made several unit tests and some console applications. Here is code from these console applications:
Application which does update:
const string DocumentNumber = "386774321";
Random randomGenerator = new Random();
using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions { IsolationLevel = IsolationLevel.RepeatableRead }))
{
using (BillingDocumentRepository billingDocumentRepository = new BillingDocumentRepository())
{
BillingOrderData orderData = billingDocumentRepository.GetByNumber(DocumentNumber);
orderData.Notes = randomGenerator.Next().ToString();
Console.WriteLine(string.Format("SECOND: {0}: Updated notes to {1}.", DateTime.Now.ToString("HH:mm:ss.fffff"), orderData.Notes));
Console.WriteLine(string.Format("SECOND: {0}: Updating order.", DateTime.Now.ToString("HH:mm:ss.fffff")));
Console.WriteLine(string.Format("SECOND: {0}: Going to sleep for 10000ms.", DateTime.Now.ToString("HH:mm:ss.fffff")));
Sleep(10000); // My custom sleep method because I didn't want to use Thread.Sleep for simulating long transaction
billingDocumentRepository.Save(orderData);
}
Console.WriteLine(string.Format("SECOND: {0}: Going to sleep for 10000ms.", DateTime.Now.ToString("HH:mm:ss.fffff")));
Sleep(10000);
Console.WriteLine(string.Format("SECOND: {0}: Completing transaction.", DateTime.Now.ToString("HH:mm:ss.fffff")));
scope.Complete();
}
Application which reads the same row in database:
while (true)
{
using (BillingDocumentRepository repository = new BillingDocumentRepository())
{
Console.WriteLine(string.Format("MAIN: {0}: Getting document.", DateTime.Now.ToString("HH:mm:ss.fffff")));
BillingOrderData billingOrderData = repository.GetByNumber("386774321");
Console.WriteLine(string.Format("MAIN: {0}: Got order with notes {1}.", DateTime.Now.ToString("HH:mm:ss.fffff"), billingOrderData.Notes));
Sleep(1000);
}
}
Problem is that first transaction (which updates row) doesn't lock row for reading at any moment. Second application is reading that row all the time with old value before scope.Complete() and than new value after that. How can I achieve locking with this model?
You should lock when reading. Locking later is "too late":
document = this.Session.CreateCriteria(typeof(T))
.Add(Restrictions.Eq("Number", documentNumber))
.SetLockMode(LockMode.Upgrade)
.SetTimeout(5)
.UniqueResult();
Or:
var doc = session.QueryOver<BillingDocument>()
.Where(c => c.Number== "2233445")
.Lock()
.Upgrade
.UnderlyingCriteria.
SetTimeout(5).
List().
FirstOrNull() as BillingDocument;
There is a session.Lock(object) method.
When you call session.Save(object), NHibernate isn't doing anything in the database until it gets flushed.
Flushing is done (depending on the flush mode, which is usually AutoFlush)
before queries (except Get and Load)
when calling flush explicitly
when committing the transaction (if the connection is created by NH I think)
When the session is flushed, the actual update, insert and delete operations are done on the database and locks are set.
In SQL Server, when the lock is set, the reading transaction is waiting until commit of the updating transaction. When it commits, it reads the committed values (when you are in "Read Committed" isolation).
I am trying to build a WCF service that exposes the functionality of a particular COM object that I do not have the original source for. I am using duplex binding so that each client has their own instance as there are events tied to each particular instance which are delivered through a callback (IAgent). It appears there is a deadlock or something because after the first action, my service blocks at my second action's lock. I have tried implementing these custom STA attribute and operation behaviors (http://devlicio.us/blogs/scott_seely/archive/2009/07/17/calling-an-sta-com-object-from-a-wcf-operation.aspx) but my OperationContext.Current is always null. Any advice is much appreciated.
Service
Collection:
private static Dictionary<IAgent, COMAgent> agents = new Dictionary<IAgent, COMAgent>();
First action:
public void Login(LoginRequest request)
{
IAgent agent = OperationContext.Current.GetCallbackChannel<IAgent>();
lock (agents)
{
if (agents.ContainsKey(agent))
throw new FaultException("You are already logged in.");
else
{
ICOMClass startup = new ICOMClass();
string server = ConfigurationManager.AppSettings["Server"];
int port = Convert.ToInt32(ConfigurationManager.AppSettings["Port"]);
bool success = startup.Logon(server, port, request.Username, request.Password);
if (!success)
throw new FaultException<COMFault>(new COMFault { ErrorText = "Could not log in." });
COMAgent comAgent = new COMAgent { Connection = startup };
comAgent.SomeEvent += new EventHandler<COMEventArgs>(comAgent_COMEvent);
agents.Add(agent, comAgent);
}
}
}
Second Action:
public void Logoff()
{
IAgent agent = OperationContext.Current.GetCallbackChannel<IAgent>();
lock (agents)
{
COMAgent comAgent = agents[agent];
try
{
bool success = comAgent.Connection.Logoff();
if (!success)
throw new FaultException<COMFault>(new COMFault { ErrorText = "Could not log off." });
agents.Remove(agent);
}
catch (Exception exc)
{
throw new FaultException(exc.Message);
}
}
}
Take a look at this very similar post: http://www.netfxharmonics.com/2009/07/Accessing-WPF-Generated-Images-Via-WCF
You have to use an OperationContextScope to have access to the current OperationContext from the newly generated thread:
System.Threading.Thread thread = new System.Threading.Thread(new System.Threading.ThreadStart(delegate
{
using (System.ServiceModel.OperationContextScope scope = new System.ServiceModel.OperationContextScope(context))
{
result = InnerOperationInvoker.Invoke(instance, inputs, out staOutputs);
}
}));