entity-framework-4

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: LINQ to Entities does not recognize the method I use Entity Framework 4.3 I write extension method: public static IQueryable<TSource> Active<TSource>(this IQueryable<TSource> source) where TSource : class, IStatusable { return source.Where(s => s.Status == (int)StatusEnum.Enabled); } This works good: var cat=Context.Categories.Active().ToList() But i need use this extension method in Select. Look simplified

问题 I know that EF4 does not support User Defined Table Types (yet). I need to write a query, that accepts a list of pairs <product_code, quantity> and returns a record set with product_code and price for each product_code passed, based on quantity . What is my best option with EF4 to model this? The calculation in the database to get the price are quite complex, and there are a lot of products, which means that most of the action should happen server-side. (For example I can't get full list of

问题 I have the following POCO: Public Class T1 <Required()> <MaxLength(128)> <Key(), Column(Order:=0)> Property K1 As String <Required()> <MaxLength(128)> <Key(), Column(Order:=1)> Property K2 As String <Required()> Property C1 As String Property C2 As String end Class I would expect C2 to be created as Nullable, but both C1 and C2 are Not Null. Adding <Required(AllowEmptyStrings:=True)> Does not make a difference, as it seems the decoration is aimed at data validation, not DB creation. So how do

问题 I have a Inheritance Hierarchy where Action is parent of ActionCompleted and ActionCancelled. Order class has a zero to one ActionCompleted and ActionCancelled. I have tried TPH and TPT (even tried edmx) but unable to get Entity to understand this relationship between Order and child actions, please suggest how do I map? //Classes public class Order { public int OrderId { get; set; } public string Name { get; set; } public ActionCompleted ACO { get; set; } public ActionCancelled ACA { get;

问题 I was trying to do the following public IList<Category> GetMainCategories() { return _context.Category .Where(x => x.ParentCategory == null) .OrderBy(x => x.SortOrder) .ToList(); } However, no matter what I try this returns no results even though I can see in the collection that ALL ParentCategory's are null? I have read EF has problems with nulls like this and have also tried .Where(x => x.ParentCategory.Equals(null)) And .Where(x => Equals(x.ParentCategory.Id, null)) .Where(x => Equals(x

问题 I am having below mentioned POCO classes. public class AppointmentModel { public InvoiceDetail InvoiceDetails { get; set; } public Invoice Invoice { get; set; } } public class InvoiceDetail { public Invoice Invoice { get; set; } } public class Invoice { public Invoice() { Id = Guid.NewGuid(); Created = DateTime.Now; } public Guid Id { get; set; } public virtual Appointment Appointment { get; set; } } I have tried to add that model inside repository is as below. public void Booking

问题 The problem: Exception Details: System.InvalidOperationException: The model item passed into the dictionary is of type 'System.Data.Entity.Infrastructure.DbQuery`1[System.Int32]', but this dictionary requires a model item of type 'migros.Models.State'. What I'm trying to do I need to pass the result of the following linq query to a View. using (var db = new migros_mockEntities1()) { var listOfIdeas = (from x in db.States select x.ID); return View(listOfIdeas); } The View requires IEnumerable

问题 Is it possible to add a migration file using DbMigrator in code instead of through the powershell commands? 回答1: DbMigrator is class for running migrations. Classes for creating migration are in System.Data.Entity.Migrations.Design. ToolingFacade is called by powershell commands. Other classes represents low level API for creating migration code. 来源： https://stackoverflow.com/questions/12353840/possible-to-add-migration-using-ef-dbmigrator

问题 I am calling SQL Server 10 from Entity Framework in C# and want to get a query hint into the request. The database has indexes which operated normally from SQL run in Management Studio, but when calling the command from C# using Entity Framework in Visual Studio, the query planner chooses a full scan when there is already an index. I am creating dynamic predicates to request data in the following form: data.attributeText = data.vegaDB.attributeText.AsExpandable().Where(parentPredicate.Compile

问题 I mean I was using a .SDF file but then had issues getting that to work with my host. So then I went back to the SQL DB I already have but I noticed that when I go to the default MVC 4 index page it is looking for that entity that I already created when I used the original DB.. but this table does not exist with the new SQL DB I switched to.. I already verified that is is pointing to the new DB buy setting the connection string in the constructer. How do I tell the code to 'RE CREATE THE