entity-framework-4

问题 My domain classes that have one-to-many mappings generally take the following form (untested code): public Customer Customer { // Public methods. public Order AddOrder(Order order) { _orders.Add(order); } public Order GetOrder(long id) { return _orders.Where(x => x.Id).Single(); } // etc. // Private fields. private ICollection<Order> _orders = new List<Order>(); } The EF4 code-only samples I've seen expose a public ICollection when dealing with one-to-many relationships. Is there a way to

问题 I am using Entity Framework 4.1 code first and ASP.NET MVC 3 and I am struggling to get my self referencing setup properly. I have a Category class. It must be self referencing to itself. A category can be a parent category when the ParentCategoryId in the table is null. If a category has a ParentCategoryId with a value then it means that it belongs to a parent category. I followed this article on Code Project. Here is my Category class: public class Category { public int Id { get; set; }

问题 I am trying to not have my Business Logic know the inner workings of my Data Layer and vica versa. But Entity Framework is making that hard. I can insert into a collection (in my Business Layer) without a reference to the ObjectContext: order.Containers.Add(new Container { ContainerId = containerId, Order = order }); And that saves fine when it comes time to do a SaveChanges() in the Data Layer. But to delete an item from a collection I need a reference to the ObjectContext. (I am case #1 in

问题 I am receiving the following error: System.InvalidOperationException was unhandled Message=The type 'Judge' is not attributed with EdmEntityTypeAttribute but is contained in an assembly attributed with EdmSchemaAttribute. POCO entities that do not use EdmEntityTypeAttribute cannot be contained in the same assembly as non-POCO entities that use EdmEntityTypeAttribute. Source=EntityFramework StackTrace: at System.Data.Entity.Internal.InternalContext.UpdateEntitySetMappingsForType(Type

问题 I just switched from Linq 2 SQL to Entity Framework, and I'm seeing some strange behaviors in EF that I'm hoping someone can help with. I tried Googling around, but I wasn't able to find other people with this same problem. I've mocked up a scenario to explain the situation. If I work directly with an EF context, I'm able to do a select within a select. For example, this executes perfectly fine: // this is an Entity Framework context that inherits from ObjectContext var dc = new MyContext();

问题 I'm tryng to save on a DB the log of a multi thread processo but I'm getting the following error: new transaction is not allowed because there are other threads running in the session. in each tread I have this function: internal bool WriteTrace(IResult result, string message, byte type) { SPC_SENDING_TRACE trace = new SPC_SENDING_TRACE( message, Parent.currentLine.CD_LINE, type, Parent.currentUser.FULLNAME, Parent.guid); Context.SPC_SENDING_TRACE.AddObject(trace); if (Context.SaveChanges

问题 I am developing a file storage application, and we have incorporated the FileStream type in our database. The system is expected to support large files. One portion of the application allows for bulk uploads of multiple documents. These documents then have to be linked to other entities within the system. One page is designed to show unlinked documents, to allow a user to link the documents one at a time to entities. After doing some load testing of the upload process, we found that the

问题 I am working on an ASP.Net MVC 3 web application using EF 4.1. Since today, I am getting this error: System.ArgumentException: Duplicate type name within an assembly and I can't figure out what is causing it. It is happening in my repository when performing a Find: public virtual T GetById(long id) { return dbset.Find(id); } Here is the stack trace: [ArgumentException: Duplicate type name within an assembly.] System.Reflection.Emit.ModuleBuilder.CheckTypeNameConflict(String strTypeName,

问题 I'm building a App that use Context of EF in Singleton Pattern like NHibernate work with Session: public class DbContextFactory { private static volatile DbContextFactory _dbContextFactory; private static readonly object SyncRoot = new Object(); public DbContext Context; public static DbContextFactory Instance { get { if (_dbContextFactory == null) { lock (SyncRoot) { if (_dbContextFactory == null) _dbContextFactory = new DbContextFactory(); } } return _dbContextFactory; } } public DbContext

问题 I want to extend an EF entity in a partial class with methods and properties. I've done this quite often. But now I would need to combine data from this entity with data from other entities. I would therefore need to able to access the entities objectcontext (if attached) to make these queries. Is there a way to get the entities objectcontext from within it? Thanx! 回答1: There is no build in way to get current ObjectContext from entity. Entities based on EntityObject class and POCO proxies