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  • Could you give me an example of how to attach an object in Deleted state – I keep getting an exception [migrated]

    - by carewithl
    From MSDN : An object in the Deleted state can only be attached when the ObjectStateManager is already tracking the relationship instance. Could you give me an example of how to attach an object in the Deleted state. I tried the following and got "System.InvalidOperationException: The object being attached is in an added or deleted state. Relationships cannot be created for objects in this state". var contact = context.Contacts.First(); Console.WriteLine(contact.Addresses.Count()); // 2 var address = contact.Addresses.First(); context.Addresses.DeleteObject(address); contact.Addresses.Attach(address); // InvalidOperationException thank you

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  • Are elements returned by Linq-to-Entities query streamed from the DB one at the time or are they retrieved all at once?

    - by carewithl
    Are elements returned by Linq-to-Entities query streamed from the database one at the time ( as they are requested ) or are they retrieved all at once: SampleContext context = new SampleContext(); // SampleContext derives from ObjectContext var search = context.Contacts; foreach (var contact in search) { Console.WriteLine(contact.ContactID); // is each Contact retrieved from the DB // only when foreach requests it? } thank you in advance

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  • ASP.Net Entity Framework, objectcontext error

    - by Chris Klepeis
    I'm building a 4 layered ASP.Net web application. The layers are: Data Layer Entity Layer Business Layer UI Layer The entity layer has my data model classes and is built from my entity data model (edmx file) in the datalayer using T4 templates (POCO). The entity layer is referenced in all other layers. My data layer has a class called SourceKeyRepository which has a function like so: public IEnumerable<SourceKey> Get(SourceKey sk) { using (dmc = new DataModelContainer()) { var query = from SourceKey in dmc.SourceKeys select SourceKey; if (sk.sourceKey1 != null) { query = from SourceKey in query where SourceKey.sourceKey1 == sk.sourceKey1 select SourceKey; } return query; } } Lazy loading is disabled since I do not want my queries to run in other layers of this application. I'm receiving the following error when attempting to access the information in the UI layer: The ObjectContext instance has been disposed and can no longer be used for operations that require a connection. I'm sure this is because my DataModelContainer "dmc" was disposed. How can I return this IEnumerable object from my data layer so that it does not rely on the ObjectContext, but solely on the DataModel? Is there a way to limit lazy loading to only occur in the data layer?

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  • Appengine datastore phantom entity - inconsistent state?

    - by aloo
    Getting a weird error on java appengine code that used to work fine (nothing has changed but the data in the datastore). I'm trying to iterate over the results of a query and change a few properties of the entities. The query does return a set of results, however, when I try to access the first result in the list, it throws an exception when trying to access any of its properties (but its key). Here's the exception: org.datanucleus.state.JDOStateManagerImpl isLoaded: Exception thrown by StateManager.isLoaded Could not retrieve entity of kind OnTheCan with key OnTheCan(3204258) org.datanucleus.exceptions.NucleusObjectNotFoundException: Could not retrieve entity of kind OnTheCan with key OnTheCan(3204258) at org.datanucleus.store.appengine.DatastoreExceptionTranslator.wrapEntityNotFoundException(DatastoreExceptionTranslator.java:60) And here is my code: PersistenceManager pm = PMF.get().getPersistenceManager(); Query query = null; List<OnTheCan> cans; query = pm.newQuery("SELECT this FROM " + OnTheCan.class.getName() + " WHERE open == true ORDER BY onTheCanId ASC"); query.setRange(0, num); cans = (List<OnTheCan>) query.execute(); for (OnTheCan c : cans) { System.err.println(c.getOnTheCanId()); // this works fine! getting the key works c.setOpen(false); // failure here with the above exception c.setAutoClosed(true); c.setEndTime(new Date(c.getStartTime().getTime() + 600000/*10*60*1000*/)); } pm.close(); The code throws the exception when trying to execute c.setOpen(false) - thats the first time I'm accessing or setting a property that isnt the key. So it seems there is a phantom entity in my datastore with key 3204258. THis entity doesn't really exist (queried the datastore from admin console) but for some reason its being returned by the query. Could my data store be in an inconsistent state? I've managed the following workaround by placing it as the first line in my for loop. Clearly an ugly hack: if (c.getOnTheCanId() == 3204258) { continue; } Any ideas?

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  • JPA - Performance with using multiple entity manager

    - by Nguyen Tuan Linh
    My situation is: The code is not mine I have two kinds of database: one is Dad, one is Son. In Dad, I have a table to store JNDI name. I will look up Dad using JNDI, create entity manager, and retrieve this table. From these retrieved JNDI names, I will create multiple entity managers using multiple Son databases. The problem is: Son have thousands of entities. It takes each Son database around 10 minutes to load all entities. If there is 4 Son databases, it will be 40 minutes. My question: Is there any way to load all entities and use them for all entity manager? Please look at the code below For each Son JNDI: Map<String, String> puSonProperties = new HashMap<String, String>(); puSonProperties.put("javax.persistence.jtaDataSource", sonJndi); EntityManagerFactory emf = Persistence.createEntityManagerFactory("PUSon", puSonProperties); PUSon - All of them use the same persistence unit log.info("Verify entity manager for son: {0} - {1}", sonCode, emSon.find(Son_configuration.class, 0) != null ? "ok" : "failed!"); This is the actual code where the loading of all entities begins. 10 mins.

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  • Going "behind Hibernate's back" to update foreign key values without an associated entity

    - by Alex Cruise
    Updated: I wound up "solving" the problem by doing the opposite! I now have the entity reference field set as read-only (insertable=false updatable=false), and the foreign key field read-write. This means I need to take special care when saving new entities, but on querying, the entity properties get resolved for me. I have a bidirectional one-to-many association in my domain model, where I'm using JPA annotations and Hibernate as the persistence provider. It's pretty much your bog-standard parent/child configuration, with one difference being that I want to expose the parent's foreign key as a separate property of the child alongside the reference to a parent instance, like so: @Entity public class Child { @Id @GeneratedValue Long id; @Column(name="parent_id", insertable=false, updatable=false) private Long parentId; @ManyToOne(cascade=CascadeType.ALL) @JoinColumn(name="parent_id") private Parent parent; private long timestamp; } @Entity public class Parent { @Id @GeneratedValue Long id; @OrderBy("timestamp") @OneToMany(mappedBy="parent", cascade=CascadeType.ALL, fetch=FetchType.LAZY) private List<Child> children; } This works just fine most of the time, but there are many (legacy) cases when I'd like to put an invalid value in the parent_id column without having to create a bogus Parent first. Unfortunately, Hibernate won't save values assigned to the parentId field due to insertable=false, updatable=false, which it requires when the same column is mapped to multiple properties. Is there any nice way to "go behind Hibernate's back" and sneak values into that field without having to drop down to JDBC or implement an interceptor? Thanks!

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  • Updating entity fields in app engine development server

    - by Joey
    I recently tried updating a field in one of my entities on the app engine local dev server via the sdk console. It appeared to have updated just fine (a simple float). However, when I followed up with a query on the entity, I received an exception: "Items in the mSomeList list must all be Key instances". mSomeList is just another list field I have in that entity, not the one I modified. Is there any reason manually changing a field would adversely throw something off such that the server gets confused? Is this a known bug? I wrote an http handler to alter the field through server code and it works fine if I take that approach. Update: (adding details) I am using the python google app engine server. Basically if I go into the Google App Engine Launcher and press the SDK Console button, then go into one of my entities and edit a field that is a float (i.e. change it from 0 to 3.5, for instance), I get the "Items in the mMyList list must all be Key instance" suddenly when I query the entity like this: query = DataModels.RegionData.gql("WHERE mRegion = :1", region) entry = query.get() the RegionData entity is what has the mMyList member. As mentioned previously, if I do not manually change the field but rather do so through server code, i.e. query = DataModels.RegionData.gql("WHERE mRegion = :1", region) entry = query.get() entry.mMyFloat = 3.5 entry.put() Then it works.

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  • Using nHibernate to map two different data models to one entity model

    - by Dan
    I have two different data models that map to the same Car entity. I needed to create a second entity called ParkedCar, which is identical to Car (and therefore inherits from it) in order to stop nhibernate complaining that two mappings exists for the same entity. public class Car { protected Car() { IsParked = false; } public virtual int Id { get; set; } public bool IsParked { get; internal set; } } public class ParkedCar : Car { public ParkedCar() { IsParked = true; } //no additional properties to car, merely exists to support mapping and signify the car is parked } The only issue is that when I come to retrieve a Car from the database using the Criteria API like so: SessionProvider.OpenSession.Session.CreateCriteria<Car>() .Add(Restrictions.Eq("Id", 123)) .List<Car>(); The query brings back Car Entities that are from the ParkedCar data model. Its as if nhibernate defaults to the specialised entity. And the mappings are defiantly looking in the right place: <class name="Car" xmlns="urn:nhibernate-mapping-2.2" table="tblCar"> <class name="ParkedCar" xmlns="urn:nhibernate-mapping-2.2" table="tblParkedCar" > How do I stop this?

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  • Doctrine 2 entity cannot be saved with its many-to-many related entities

    - by user1333185
    I'm writing a project in ZF and have many-to-many related accounts and videos entities and I provide the account with the videos collection. When I try to save the account I receive the following error: A new entity was found through the relationship 'Entities\Account#playlistVideos' that was not configured to cascade persist operations for entity: Entities\Video@000000004d5f02ef00000000196757dc. Explicitly persist the new entity or configure cascading persist operations on the relationship. If you cannot find out which entity causes the problem implement 'Entities\Video#__toString()' to get a clue. I found a suggested solution with cascade={"persist"} which should allow videos to be saved together with the account by only specifying $this-em-persist($account) but then I get the error: Fatal error: method_exists(): The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "Proxies\EntitiesAccountProxy" of the object you are trying to operate on was loaded before unserialize() gets called or provide a __autoload() function to load the class definition in... The same happens when I try to manually persist videos and account. Thank you for the help in advance.

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  • Under what circumstances will an entity be able to lazily load its relationships in JPA

    - by Mowgli
    Assuming a Java EE container is being used with JPA persistence and JTA transaction management where EJB and WAR packages are inside a EAR package. Say an entity with lazy-load relationships has just been returned from a JPQL search, such as the getBoats method below: @Stateless public class BoatFacade implements BoatFacadeRemote, BoatFacadeLocal { @PersistenceContext(unitName = "boats") private EntityManager em; @Override public List<Boat> getBoats(Collection<Integer> boatIDs) { if(boatIDs.isEmpty()) { return Collections.<Boat>emptyList(); } Query query = em.createNamedQuery("getAllBoats"); query.setParameter("boatID", boatIDs); List<Boat> boats = query.getResultList(); return boats; } } The entity: @Entity @NamedQuery( name="getAllBoats", query="Select b from Boat b where b.id in : boatID") public class Boat { @Id private long id; @OneToOne(fetch=FetchType.LAZY) private Gun mainGun; public Gun getMainGun() { return mainGun; } } Where will its lazy-load relationships be loadable (assuming the same stateless request): Same JAR: A method in the same EJB A method in another EJB A method in a POJO in the same EJB JAR Same EAR, but outside EJB JAR: A method in a web tier managed bean. A method in a web tier POJO. Different EAR: A method in a different EAR which receives the entity through RMI. What is it that restricts the scope, for example: the JPA transaction, persistence context or JTA transaction?

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  • MVC Dropdown List isn't binding to the model.

    - by Rod McLeay
    Hi, I am trying set up a simple dropdown list but I dont seem to be able to get it to bind to the Model. I am using Asp.Net MVC and nhibernate. My dropdown list is declared like so: <%= Html.DropDownListFor(model => model.Project, (IEnumerable<SelectListItem>)ViewData["Projects"], " -- Select -- ", new { name = "Project" })%> I set up the select list like so: ViewData["Projects"] = new SelectList(projectRepository.GetAll(), "EntityGUID", "Name", editEntity.Project); This seems to bind the select list to the Dropdown fine, but the SelectedValue is not set. it shows up as the default --- Select --- Also when I save this data, the dropdown does not bind to the model, I have to manually set the object like so to save it: entity.Project = projectRepository.GetById(new Guid(Request["Project"].ToString())); I believe I have take the correct messures to have this item bind directly to my model. Is there something I am missing here? Many thanks for your time, Rod

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  • MVC map to nullable bool in model

    - by fearofawhackplanet
    With a view model containing the field: public bool? IsDefault { get; set; } I get an error when trying to map in the view: <%= Html.CheckBoxFor(model => model.IsDefault) %> Cannot implicitly convert type 'bool?' to 'bool'. An explicit conversion exists (are you missing a cast?) I've tried casting, and using .Value and neither worked. Note the behaviour I would like is that submitting the form should set IsDefault in the model to true or false. A value of null simply means that the model has not been populated.

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  • Reattaching an object graph to an EntityContext: "cannot track multiple objects with the same key"

    - by dkr88
    Can EF really be this bad? Maybe... Let's say I have a fully loaded, disconnected object graph that looks like this: myReport = {Report} {ReportEdit {User: "JohnDoe"}} {ReportEdit {User: "JohnDoe"}} Basically a report with 2 edits that were done by the same user. And then I do this: EntityContext.Attach(myReport); InvalidOperationException: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key. Why? Because the EF is trying to attach the {User: "JohnDoe"} entity TWICE. This will work: myReport = {Report} {ReportEdit {User: "JohnDoe"}} EntityContext.Attach(myReport); No problems here because the {User: "JohnDoe"} entity only appears in the object graph once. What's more, since you can't control how the EF attaches an entity, there is no way to stop it from attaching the entire object graph. So really if you want to reattach a complex entity that contains more than one reference to the same entity... well, good luck. At least that's how it looks to me. Any comments? UPDATE: Added sample code: // Load the report Report theReport; using (var context1 = new TestEntities()) { context1.Reports.MergeOption = MergeOption.NoTracking; theReport = (from r in context1.Reports.Include("ReportEdits.User") where r.Id == reportId select r).First(); } // theReport looks like this: // {Report[Id=1]} // {ReportEdit[Id=1] {User[Id=1,Name="John Doe"]} // {ReportEdit[Id=2] {User[Id=1,Name="John Doe"]} // Try to re-attach the report object graph using (var context2 = new TestEntities()) { context2.Attach(theReport); // InvalidOperationException }

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  • Doubt about django model API

    - by Clash
    Hello guys! So, here is what I want to do. I have a model Staff, that has a foreign key to the User model. I also have a model Match that has a foreign key to the User model. I want to select how much Matches every Staff has. I don't know how to do that, so far I only got it working for the User model. From Staff, it will not allow to annonate Match. This is what is working right now User.objects.annotate(ammount=Count("match")).filter(Q(ammount__gt=0)).order_by("ammount") And this is what I wanted to do Staff.objects.annotate(ammount=Count("match")).filter(Q(ammount__gt=0)).order_by("ammount") And by the way, is there any way to filter the matches? I want to filter the matches by a certain column. Thanks a lot in advance!

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  • Handling undo and edit flag on window with several model objects

    - by Rui Pacheco
    Hi, I've a window that will hold several instances of a model object, listed in a table. The model object is updated using a text view. What is the best way to keep the edit flag and undo manager in synch with the content of the different model objects? I'm thinking creating an instance of the undo manager on the model object and manually set the undo manager for the text view every time the user choses a new model object. Does the undo manager also handle the edited flag?

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  • ASP.NET MVC - Disable Html Helper control using boolean value from Model

    - by The Matt
    I am outputting a textbox to the page using the Html helpers. I want to add the disabled attribute dynamically based on whether or not a boolean value in my model is true or false. My model has a method that returns a boolean value: <% =Model.IsMyTextboxEnabled() %> I currently render the textbox like follows, but I want to now enabled or disable it: <% =Html.TextBox("MyTextbox", Model.MyValuenew { id = "MyTextbox", @class = "MyClass" })%> If the return value of Model.IsMyTextboxEnabled() == true I want the following to be output: <input class="MyClass" id="MyTextbox" name="MyTextbox" type="text" value="" /> If it == false, I want it to output as: <input class="MyClass" id="MyTextbox" name="MyTextbox" type="text" value="" disabled /> What is the cleanest way to do this?

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  • Two Tables Serving as one Model in Rails

    - by matsko
    Is is possible in rails to setup on model which is dependant on a join from two tables? This would mean that for the the model record to be found/updated/destroyed there would need to be both records in both database tables linked together in a join. The model would just be all the columns of both tables wrapped together which may then be used for the forms and so on. This way when the model gets created/updated it is just one form variable hash that gets applied to the model? Is this possible in Rails 2 or 3?

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  • Can I bind multiple forms to a single model using the default model binder?

    - by MedicineMan
    I have a complex page with several forms on it. The page is divided into sections, and each section has a continue button on it. The page is bound to a pageViewModel, each section addresses a different set of properties on the model. The continue button makes an ajax call to the controller, and the model binder binds it appropriately to the appropriate sections of the model. The section is refreshed appropriately. Finally, I would like to have a save button at the bottom of the page that takes all the forms, and binds all of the forms to the model. The model, at this point has all of the properties filled out, and can be processed accordingly. Can I accomplish this by some ASP MVC magic?

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  • Quering distinct values throught related model

    - by matheus.emm
    Hi! I have a simple one-to-many (models.ForeignKey) relationship between two of my model classes: class TeacherAssignment(models.Model): # ... some fields year = models.CharField(max_length=4) class LessonPlan(models.Model): teacher_assignment = models.ForeignKey(TeacherAssignment) # ... other fields I'd like to query my database to get the set of distinct years of TeacherAssignments related to at least one LessonPlan. I'm able to get this set using Django query API if I ignore the relation to LessonPlan: class TeacherAssignment(models.Model): # ... model's fields def get_years(self): year_values = self.objects.all().values_list('year').distinct().order_by('-year') return [yv[0] for yv in year_values if len(yv[0]) == 4] Unfortunately I don't know how to express the condition that the TeacherAssignment must be related to at least one LessonPlan. Any ideas how I'd be able to write the query? Thanks in advance.

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  • EntityFramework WCF issue

    - by Andres Blanco
    Right now i'm doing some tests involving entityFramework and WCF. As I understand, the EntityObjects generated are DataContracts and so, they can be serialized to the client. In my example I have a "Country" entity wich has 1 "Currency" as a property, when I get a Country and try to send it to the client, it throws an exception saying the data cant be written. But, the thing is, if I Get a Currency (which has a collection of Countries) and dont load its countries, it does work. The client gets all the entities. So, as a summary: - I have an entity with another entity as a property and cant be serialized. - I have another entity with an empty list of properties and it is successfully serialized. Any ideas on how to make it work?

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  • Configuration and Model-View

    - by HH
    I am using the Model-View pattern on a small application I'm writing. Here's the scenario: The model maintains a list of directories from where it can extract the data that it needs. The View has a Configuration or a Setting dialog where the user can modify this list of directories (the dialog has a JList displaying the list in addition to add and remove buttons). I need some advice from the community: The View needs to communicate these changes to the model. I thought first of adding to the model these methods: addDirectory() and removeDirectory(). But I am trying to limit the number of methods (or channels) that the View can use to communicate with and manipulate the model. Is there any good practice for this? Thank you.

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  • Django: Extending User Model - Inline User fields in UserProfile

    - by Jack Sparrow
    Is there a way to display User fields under a form that adds/edits a UserProfile model? I am extending default Django User model like this: class UserProfile(models.Model): user = models.OneToOneField(User, unique=True) about = models.TextField(blank=True) I know that it is possible to make a: class UserProfileInlineAdmin(admin.TabularInline): and then inline this in User ModelAdmin but I want to achieve the opposite effect, something like inverse inlining, displaying the fields of the model pointed by the OneToOne Relationship (User) in the page of the model defining the relationship (UserProfile). I don't care if it would be in the admin or in a custom view/template. I just need to know how to achieve this. I've been struggling with ModelForms and Formsets, I know the answer is somewhere there, but my little experience in Django doesn't allow me to come up with the solution yet. A little example would be really helpful!

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  • Howw to add new value with generic Repository if there are foreign keys (EF-4)?

    - by Phsika
    i try to write a kind of generic repository to add method. Everything is ok to add but I have table which is related with two tables with FOREIGN KEY.But Not working because of foreign key public class DomainRepository<TModel> : IDomainRepository<TModel> where TModel : class { #region IDomainRepository<T> Members private ObjectContext _context; private IObjectSet<TModel> _objectSet; public DomainRepository() { } public DomainRepository(ObjectContext context) { _context = context; _objectSet = _context.CreateObjectSet<TModel>(); } //do something..... public TModel Add<TModel>(TModel entity) where TModel : IEntityWithKey { EntityKey key; object originalItem; key = _context.CreateEntityKey(entity.GetType().Name, entity); _context.AddObject(key.EntitySetName, entity); _context.SaveChanges(); return entity; } //do something..... } Calling REPOSITORY: //insert-update-delete public partial class AddtoTables { public table3 Add(int TaskId, int RefAircraftsId) { using (DomainRepository<table3> repTask = new DomainRepository<table3>(new TaskEntities())) { return repTask.Add<table3>(new table3() { TaskId = TaskId, TaskRefAircraftsID = RefAircraftsId }); } } } How to add a new value if this table includes foreign key relation

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  • Rails: Ajax-enabled form without a model object

    - by Caffeine Coma
    I'm new to Rails and having a hard time figuring out how to create a form that submits over Ajax without having a corresponding model object. My use case is a simple form that collects an email address and sends it an email; there's nothing to be persisted, so no model. In cases where I do have a model, I've had success with form_for(@model, remote: true). I can't seem to find the right helper for the case where there is no model. I tried form_tag(named_path, remote: true) and that works, but does not use Ajax. Pointers to an example with an example with a proper controller, .html.erb and routes.rb would be really appreciated.

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  • Is it possible that two requests at the same time double this code? (prevent double database entry)

    - by loostro
    1) The controller code (Symfony2 framework): $em = $this->getDoctrine()->getEntityManager(); // get latest toplist $last = $em->getRepository('RadioToplistBundle:Toplist')->findOneBy( array('number' => 'DESC') ); // get current year and week of the year $week = date('W'); $year = date('Y'); // if: // [case 1]: $last is null, meaning there are no toplists in the database // [case 2]: $last->getYear() or $last->getWeek() do not match current // year and week number, meaning that there are toplists in the // database, but not for current week // then: // create new toplist entity (for current week of current year) // else: // do nothing (return) if($last && $last->getYear() == $year && $last->getWeek() == $week) return; else { $new = new Toplist(); $new->setYear($year); $new->setWeek($week); $em->persist($new); $em->flush(); } This code is executed with each request to view toplist results (frontend) or list of toplists (backend). Anytime someone wants to access the toplist we first check if we should create a new toplist entity (for new week). 2) The question is: Is it possible that: User A goes to mydomain.com/toplist at 00:00:01 on Monday - the code should generate new entity the server slows down and it takes him 3 seconds to execute the code so new toplist entity is saved to database at 00:00:04 on Monday User B goes to mydomain.com/toplist at 00:00:02 on Monday at 00:00:02 there the toplist is not yet saved in database, thus UserB's request triggers the code to create another toplist entity And so.. after a few seconds we have 2 toplist entities for current week. Is this possible? How should I prevent this?

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