How can I save something to my database in the entity framework within a separate thread?
What I want to do could look like that, but obviously doesn't work like that:
public class ThingsHandler : IHttpHandler
{
private DatabaseContext db = new DatabaseContext();
private void ProcessThing()
{
System.Threading.Tasks.Task.Factory.StartNew(() =>
{
Thing dbThing = db.Things.Where(...).AsEnumerable().LastOrDefault();
dbThing.some_property = true;
db.SaveChanges();
}
}
I hope, I was able to make clear, what I would like to achieve. But what do I need to do?
If you want to stay with task, you should place context initialization inside task:
System.Threading.Tasks.Task.Factory.StartNew(() =>
{
var db = new DatabaseContext();
Thing dbThing = db.Things.Where(...).AsEnumerable().LastOrDefault();
dbThing.some_property = true;
db.SaveChanges();
}
But if you use EF6, you might want to use Async methods:
private async void ProcessThing()
{
Thing dbThing = await db.Things.Where(...).AsEnumerable().LastOrDefaultAsync();
dbThing.some_property = true;
await db.SaveChangesAsync();
}
Related
I'm having some serious issues with Fluent Nhibernate in my ASP.NET WebForms app when trying to modify a child object and then saving the parent object.
My solution is currently made of 2 projects :
Core : A class library where all entities & repositories classes are located
Website : The ASP.NET 4.5 WebForms application
Here is my simple mapping for my Employee object:
public class EmployeeMap : ClassMap<Employee>
{
public EmployeeMap()
{
Id(x => x.Id).GeneratedBy.Identity();
Map(x => x.DateCreated);
Map(x => x.Username);
Map(x => x.FirstName);
Map(x => x.LastName);
HasMany(x => x.TimeEntries).Inverse().Cascade.All().KeyColumn("Employee_id");
}
}
Here is my my mapping for the TimeEntry object:
public class TimeEntryMap : ClassMap<TimeEntry>
{
public TimeEntryMap()
{
Id(x => x.Id).GeneratedBy.Identity();
Map(x => x.DateCreated);
Map(x => x.Date);
Map(x => x.Length);
References(x => x.Employee).Column("Employee_id").Not.Nullable();
}
}
As stated in the title, i'm using one session per request in my web app, using this code in Gobal.asax:
public static ISessionFactory SessionFactory = Core.SessionFactoryManager.CreateSessionFactory();
public static ISession CurrentSession
{
get { return (ISession)HttpContext.Current.Items["current.session"]; }
set { HttpContext.Current.Items["current.session"] = value; }
}
protected Global()
{
BeginRequest += delegate
{
System.Diagnostics.Debug.WriteLine("New Session");
CurrentSession = SessionFactory.OpenSession();
};
EndRequest += delegate
{
if (CurrentSession != null)
CurrentSession.Dispose();
};
}
Also, here is my SessionFactoryManager class:
public class SessionFactoryManager
{
public static ISession CurrentSession;
public static ISessionFactory CreateSessionFactory()
{
return Fluently.Configure()
.Database(MsSqlConfiguration.MsSql2008.ConnectionString(c => c.FromConnectionStringWithKey("Website.Properties.Settings.WebSiteConnString")))
.Mappings(m => m
.FluentMappings.AddFromAssembly(Assembly.GetExecutingAssembly()))
.ExposeConfiguration(cfg => new SchemaUpdate(cfg).Execute(false, true))
.BuildSessionFactory();
}
public static ISession GetSession()
{
return (ISession)HttpContext.Current.Items["current.session"];
}
}
Here is one of my repository class, the one i use to handle the Employee's object data operations:
public class EmployeeRepository<T> : IRepository<T> where T : Employee
{
private readonly ISession _session;
public EmployeeRepository(ISession session)
{
_session = session;
}
public T GetById(int id)
{
T result = null;
using (ITransaction tx = _session.BeginTransaction())
{
result = _session.Get<T>(id);
tx.Commit();
}
return result;
}
public IList<T> GetAll()
{
IList<T> result = null;
using (ITransaction tx = _session.BeginTransaction())
{
result = _session.Query<T>().ToList();
tx.Commit();
}
return result;
}
public bool Save(T item)
{
var result = false;
using (ITransaction tx = _session.BeginTransaction())
{
_session.SaveOrUpdate(item);
tx.Commit();
result = true;
}
return result;
}
public bool Delete(T item)
{
var result = false;
using (ITransaction tx = _session.BeginTransaction())
{
_session.Delete(_session.Load(typeof (T), item.Id));
tx.Commit();
result = true;
}
return result;
}
public int Count()
{
var result = 0;
using (ITransaction tx = _session.BeginTransaction())
{
result = _session.Query<T>().Count();
tx.Commit();
}
return result;
}
}
Now, here is my problem. When i'm trying to insert Employee(s), everything is fine. Updating is also perfect... well, as long as i'm not updating one of the TimeEntry object referenced in the "TimeEntries" property of Employee...
Here is where an exception is raised (in a ASPX file of the web project):
var emp = new Employee(1);
foreach (var timeEntry in emp.TimeEntries)
{
timeEntry.Length += 1;
}
emp.Save();
Here is the exception that is raised:
[NonUniqueObjectException: a different object with the same identifier
value was already associated with the session: 1, of entity:
Core.Entities.Employee]
Basically, whenever I try to
Load an employee and
Modify one of the saved TimeEntry, I get that exception.
FYI, I tried replacing the SaveOrUpdate() in the repository for Merge(). It did an excellent job, but when creating an object using Merge(), my object never gets it's Id set.
I also tried creating and flushing the ISession in each function of my repository. It made no sense because as soon as i was trying to load the TimeEntries property of an Employee, an exception was raised, saying the object could not be lazy-loaded as the ISession was closed...
I'm at lost and would appreciate some help. Any suggestion for my repository is also welcome, as i'm quite new to this.
Thanks you guys!
This code
var emp = new Employee(1);
foreach (var timeEntry in emp.TimeEntries)
{
timeEntry.Length += 1;
}
emp.Save();
is creating a new Employee object, presumable with an ID of 1 passed through the constructor. You should be loading the Employee from the database, and your Employee object should not allow the ID to be set since you are using an identity column. Also, a new Employee would not have any TimeEntries and the error message clearly points to an Employee instance as the problem.
I'm not a fan of transactions inside repositories and I'm really not a fan of generic repositories. Why is your EmployeeRepository a generic? Shouldn't it be
public class EmployeeRepository : IRepository<Employee>
I think your code should look something like:
var repository = new EmployeeRepository(session);
var emp = repository.GetById(1);
foreach (var timeEntry in emp.TimeEntries)
{
timeEntry.Length += 1;
}
repository.Save(emp);
Personally I prefer to work directly with the ISession:
using (var txn = _session.BeginTransaction())
{
var emp = _session.Get<Employee>(1);
foreach (var timeEntry in emp.TimeEntries)
{
timeEntry.Length += 1;
}
txn.Commit();
}
This StackOverflow Answer gives an excellent description of using merge.
But...
I believe that you are facing issues with setting up a correct session pattern for your application.
I you suggest to take a look at session-per-request pattern
where in you create a single NHibernate session object per request. the session is opened when the request is received and closed/flushed on generating a response.
Also make sure that instead of using SessionFactory.OpenSession() to get a session try using SessionFactory.GetCurrentSession() which puts the onus on NHibernate to return you the current correct session.
I hope this pushes you in the right direction.
I'm using a Linq query to retrieve entities from an SQL server using the Entity Framework. When I update an entitiy, the EF is caching the result. I suspect this is because the ObjectContext is in a static variable (below). The only way to refresh the data using my code below is to call a method and set _db to null when there might be stale data displayed (Eg: in a GridView). Is there a way to just prevent it from caching, or to add some sort of end request handler to call this method on my data layer instead of needing to detect when there may be stale data displayed?
private static ServiceEntities _db;
protected static ServiceEntitiesDb
{
get
{
if (_db == null)
{
_db = new ServiceEntities();
_db.Contacts.MergeOption = MergeOption.OverwriteChanges; // failed
}
return _db;
}
}
public static IEnumerable<Contact> GetContactsByName(string name) {
var items = Db.Contacts;
var filteredName = items.Where(i => (i.Name??string.Empty).IndexOf(name) >=0);
return filteredName;
}
The slightly verbose solution (which I wanted to avoid) is to wrap it in a using block. Ie:
public static IEnumerable<Contact> GetContactsByName(string name) {
var items = Db.Contacts;
var filteredName = items.Where(i => (i.Name??string.Empty).IndexOf(name) >=0);
return filteredName;
}
Becomes
public static IEnumerable<Contact> GetContactsByName(string name) {
using (var db = new SomeContext()) {
var items = db.Contacts;
var filteredName = items.Where(i => (i.Name??string.Empty).IndexOf(name) >=0);
return filteredName;
}
}
I've been trying to implement form validation correctly and a discussion on fubu mailing list has been the most helpful (http://groups.google.com/group/fubumvc-devel/browse_thread/thread/d54b135fe0254653/12180cd86e9dc50b).
I'm still not entirely clear on certain points, I'm a newbie so I'm going through some yak shaving.
It seems like the example given in the discussion performed the validation within the controller itself using IsValid(model).
I'm trying to avoid this by decorating my input model with validation attributes such as Required and then use the validation configuration to Transfer on failure (via a policy).
this.Validation(x => {
x.Actions
.Include(call => call.HasInput && call.InputType().Name.EndsWith("Input"));
x.Failures
.ApplyPolicy<AccountValidationFailedPolicy>();
});
And here's the class that implments the policy:
public class AccountValidationFailedPolicy : IValidationFailurePolicy {
public bool Matches(ValidationFailure context) {
return (context.InputType() == typeof (RegisterAccountInput));
}
public void Handle(ValidationFailure context) {
var incomingRequest = (RegisterAccountInput) context.InputModel;
var failedValidation = new RegisterationFailedNotification {
CVV = incomingRequest.CVV,
AcceptTerms = incomingRequest.AcceptTerms,
Countries = incomingRequest.Countries,
PhoneNumber = incomingRequest.PhoneNumber,
PIN = incomingRequest.PIN
};
FubuContinuation.TransferTo(failedValidation);
}
}
Handle simply tries to Transfer to another action via a new model, copying the values into the new model so that I can redisplay them again on the form.
I must be doing something wrong here, because it's not transferring anywhere.
I have a class with this method which I was hoping would handle it.
public AccountViewModel New(RegisterationFailedNotification notification) {
....
}
Am I on track here, or is there something fundamental that I'm not getting? Perhaps a policy is not the thing to do here?
#stantona
The policy mechanism will work here. I'll spare you the details about how I plan to make this simpler (very soon), and note that your use of FubuContinuation.TransferTo simply creates a FubuContinuation -- it doesn't execute it.
Here's what you need:
public class AccountValidationFailedPolicy : IValidationFailurePolicy {
private readonly IFubuRequest _request;
private readonly IValidationContinuationHandler _handler;
public AccountValidationFailedPolicy(IFubuRequest request, IValidationContinuationHandler handler) {
_request = request;
_handler = handler;
}
public bool Matches(ValidationFailure context) {
return (context.InputType() == typeof (RegisterAccountInput));
}
public void Handle(ValidationFailure context) {
var incomingRequest = (RegisterAccountInput) context.InputModel;
var failedValidation = new RegisterationFailedNotification {
CVV = incomingRequest.CVV,
AcceptTerms = incomingRequest.AcceptTerms,
Countries = incomingRequest.Countries,
PhoneNumber = incomingRequest.PhoneNumber,
PIN = incomingRequest.PIN
};
var continuation = FubuContinuation.TransferTo(failedValidation);
_request.Set(continuation);
_handler.Handle();
}
}
I am mocking a wrapper to an MSMQ. The wrapper simply allows an object instance to be created that directly calls static methods of the MessageQueue class.
I want to test reading the queue to exhaustion. To do this I would like the mocked wrapper to return some good results and throw an exception on the fourth call to the same method. The method accepts no parameters and returns a standard message object.
Can I set up this series of expectations on the method in Moq?
Yup, this is possible if you don't mind jumping through a few minor hoops. I've done this for one of my projects before. Alright here is the basic technique. I just tested it out in Visual Studio 2008, and this works:
var mockMessage1 = new Mock<IMessage>();
var mockMessage2 = new Mock<IMessage>();
var mockMessage3 = new Mock<IMessage>();
var messageQueue = new Queue<IMessage>(new [] { mockMessage1.Object, mockMessage2.Object, mockMessage3.Object });
var mockMsmqWrapper = new Mock<IMsmqWrapper>();
mockMsmqWrapper.Setup(x => x.GetMessage()).Returns(() => messageQueue.Dequeue()).Callback(() =>
{
if (messageQueue.Count == 0)
mockMsmqWrapper.Setup(x => x.GetMessage()).Throws<MyCustomException>();
});
A few notes:
You don't have to return mocked messages, but it's useful if you want to verify expectations on each message as well to see if certain methods were called or properties were set.
The queue idea is not my own, just a tip I got from a blog post.
The reason why I am throwing an exception of MyCustomException is because the Queue class automatically throws a InvalidOperationException. I wanted to make sure that the mocked MsmqWrapper object throws an exception because of Moq and not because of the queue running out of items.
Here's the complete code that works. Keep in mind that this code is ugly in some places, but I just wanted to show you how this could be tested:
public interface IMsmqWrapper
{
IMessage GetMessage();
}
public class MsmqWrapper : IMsmqWrapper
{
public IMessage GetMessage()
{
throw new NotImplementedException();
}
}
public class Processor
{
private IMsmqWrapper _wrapper;
public int MessagesProcessed { get; set; }
public bool ExceptionThrown { get; set; }
public Processor(IMsmqWrapper msmqWrapper)
{
_wrapper = msmqWrapper;
}
public virtual void ProcessMessages()
{
_wrapper.GetMessage();
MessagesProcessed++;
_wrapper.GetMessage();
MessagesProcessed++;
_wrapper.GetMessage();
MessagesProcessed++;
try
{
_wrapper.GetMessage();
}
catch (MyCustomException)
{
ExceptionThrown = true;
}
}
}
[Test]
public void TestMessageQueueGetsExhausted()
{
var mockMessage1 = new Mock<IMessage>();
var mockMessage2 = new Mock<IMessage>();
var mockMessage3 = new Mock<IMessage>();
var messageQueue = new Queue<IMessage>(new [] { mockMessage1.Object, mockMessage2.Object, mockMessage3.Object });
var mockMsmqWrapper = new Mock<IMsmqWrapper>();
mockMsmqWrapper.Setup(x => x.GetMessage()).Returns(() => messageQueue.Dequeue()).Callback(() =>
{
if (messageQueue.Count == 0)
mockMsmqWrapper.Setup(x => x.GetMessage()).Throws<InvalidProgramException>();
});
var processor = new Processor(mockMsmqWrapper.Object);
processor.ProcessMessages();
Assert.That(processor.MessagesProcessed, Is.EqualTo(3));
Assert.That(processor.ExceptionThrown, Is.EqualTo(true));
}
Somehow this update code is not working:
Here is my Controller code:
private UserRepository repo = new UserRepository();
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(int id, UserInfo user_)
{
try
{
repo.UpdateUser(user_);
return RedirectToAction("Index");
}
catch
{
return View();
}
}
Here is the repo code that is used above (UserRepository)
private UsersDataContext db = new UsersDataContext();
public void UpdateUser(UserInfo user_)
{
UserInfo origUser = GetUser(user_.Id);
origUser.First = user_.First;
origUser.Last = user_.Last;
origUser.City = user_.City;
origUser.Country = user_.Country;
origUser.State = user_.State;
origUser.Street_Address = user_.Street_Address;
db.SubmitChanges();
}
public UserInfo GetUser(int id_)
{
return db.UserInfos.SingleOrDefault(d => d.Id == id_);
}
EDIT:
Note that when debugging everything is running fine (no exceptions) but when it redirects back to Index the data has not been updated when the changes from the update.
i just changed the userrepository to the following:
private UsersDataContext db = new UsersDataContext();
public void UpdateUser(UserInfo user_)
{
UserInfo origUser = db.UserInfos.SingleOrDefault(d => d.Id == id_);
origUser.First = user_.First;
origUser.Last = user_.Last;
origUser.City = user_.City;
origUser.Country = user_.Country;
origUser.State = user_.State;
origUser.Street_Address = user_.Street_Address;
db.SubmitChanges();
}
so all i did was move the GetUser() method inline and it worked.
It might have been a red herring and it was just a caching issue . .
You don't mention how you've defined UserInfo, is it a struct or a class?
If it's a struct, returning it from GetUser will create a new object and thus you will not update the database object, only a local copy of it.
Moving the GetUser inline avoid this temp copy creation and that's likely why it's working.
afaik you could do something like
public void GetUser(int id_, out UserInfo user_)
{
user_ = db.UserInfos.SingleOrDefault(d => d.Id == id_);
}
You would then call it like this
public void UpdateUser(UserInfo user_)
{
UserInfo origUser;
GetUser(user_.Id, out origUser);
origUser.First = user_.First;
origUser.Last = user_.Last;
origUser.City = user_.City;
origUser.Country = user_.Country;
origUser.State = user_.State;
origUser.Street_Address = user_.Street_Address;
db.SubmitChanges();
}
Maybe you disabled Object Tracking?