entity-framework

问题 Why does EntityFramework add a 1 by default to a newly created EDMX file?. Say I have a database called EmployeesDB , choosing Add > New ADO.Net Data Entity data model and choosing this database in the wizard creates multiple files, including the EmployeeDB.Designer.cs , where we have public partial class SchoolDBEntities1 : ObjectContext Why is this 1 needed here? It just feels like one of those quick-and-dirty code snippets "Name it like this for now, and give it a proper name latter things

问题 Model: public class MenuItem { public Guid Id {get;set;} public virtual Guid? ParentMenuItemId {get;set;} public virtual MenuItem ParentMenuItem {get;set;} public virtual ICollection<MenuItem> ChildMenuItems {get;set;} } current mapping: HasOptional(m => m.ParentMenuItem).WithMany(p => p.ChildMenuItems).HasForeignKey(m => m.ParentMenuItemId); I tried adding the WillCascadeOnDelete(true) , but I got an error. How should I update my mapping to allow for cascading deletes? So, If I delete a

问题 I recently updated my project from Database First to a Code First Model, using this method: Link Everything seemed to be working until I wanted to update my FK and PKs on an existing table. This was a 1-0, 1-1 relationship. So the PK of Company table was the FK and PK of the DriverScorecardSetting table. So this is the entity that the Tool generated for the DriverScorecardSetting table. [Table("DriverScorecardSetting")] public partial class DriverScorecardSetting { [Key] [DatabaseGenerated

问题 I recently updated my project from Database First to a Code First Model, using this method: Link Everything seemed to be working until I wanted to update my FK and PKs on an existing table. This was a 1-0, 1-1 relationship. So the PK of Company table was the FK and PK of the DriverScorecardSetting table. So this is the entity that the Tool generated for the DriverScorecardSetting table. [Table("DriverScorecardSetting")] public partial class DriverScorecardSetting { [Key] [DatabaseGenerated

问题 I would like a sample of code. At the moment I use linq in c# and asp.net 4 ef4 var querySlotOrder = from slot in context.CmsSlots where slot.SlotId == myCurrentSlotId select slot; if (querySlotOrder.SlotOrder == myNewSlotOrder) e.Cancel = true; This linq query return only a record. Using VAR I cannot get the Typed Object and I cannot access its property SlotOrder. How to change the query? thanks for your help Usefully resource on the topic: http://msdn.microsoft.com/en-us/library/bb384065

问题 I'm puzzled as to why this code is not working, it should save changes to database after the loops but when I place the SaveChanges method inside the loop, it saves the record into the database but outside it doesn't save anything? it's about only 300 ~ 1000 records static bool lisReady = false; static bool sacclReady = false; static void Main(string[] args) { Logger("Starting services"); ConnectDBLis().Wait(); ConnectDBSaccl().Wait(); Thread.Sleep(1000); if (lisReady & sacclReady){ //start

问题 I'm puzzled as to why this code is not working, it should save changes to database after the loops but when I place the SaveChanges method inside the loop, it saves the record into the database but outside it doesn't save anything? it's about only 300 ~ 1000 records static bool lisReady = false; static bool sacclReady = false; static void Main(string[] args) { Logger("Starting services"); ConnectDBLis().Wait(); ConnectDBSaccl().Wait(); Thread.Sleep(1000); if (lisReady & sacclReady){ //start

问题 I have a Linq query that queries the following tables: Tasks with a one-to-many link to: TaskLinks and TaskLinks has a one-to-one link to a Table called Entities. I am trying to select the task, eager load (via .Include) the TaskLinks and select the Entity linked to the TaskLink. But I need to filter the Task (by Access Level int) and the TaskLinks so that I don't include any Inactive (bool) records. Here is my Linq query: Tasks.Where(t => t.AccessLevel <= 5) .Include(tl => tl.TaskLinks.Where

问题 OK, this is an interesting and most importably real urgent problem for me to solve... In order for others to neatly comprehend it, I've stretched myself to make a well illustrated post. The Object Model So I have this simple, easy and "beautiful" model in mind. See the first picture. (You can ignore PathEntry , it's not relevant in my situation.) The idea is that a MediaFeedItem owns: a collection of ThumbnailFileEntries (accesible through the ThumbnailFiles property) at most 1 raw FileEntry

问题 OK, this is an interesting and most importably real urgent problem for me to solve... In order for others to neatly comprehend it, I've stretched myself to make a well illustrated post. The Object Model So I have this simple, easy and "beautiful" model in mind. See the first picture. (You can ignore PathEntry , it's not relevant in my situation.) The idea is that a MediaFeedItem owns: a collection of ThumbnailFileEntries (accesible through the ThumbnailFiles property) at most 1 raw FileEntry