entity-framework-4.1

问题 I have an class public class Foo { public int UserId { get; set; } } and I'm using the code first fluent mapping to map this to the database. Property(i => i.UserId) .HasColumnName("userno"); the only problem is that userno is actually a char(10) in the database. How do I go about casting or converting this type? as I currently get this error. The 'UserId' property on 'Foo' could not be set to a 'String' value. You must set this property to a non-null value of type 'Int32'. Thanks 回答1: Entity

问题 I've asked the question a few different times in a few different ways and I haven't yet gotten any responses. I'm trying again because I feel like my solution is too convoluted and I must be missing something simpler to do. Using EF 4.1, POCO, DbContext API, AutoMapper, and Razor in an MVC 3 application. I have a many-to-many relationship between two of my entities: Proposals and CategoryTags. I can successfully map (Automapper) a Proposal to my ProposalViewModel including the collection of

问题 Given a DbContext that implements 2 interfaces like so: public interface IQueryEntities { IQueryable<User> Users { get; } IQueryable<Computer> Computers { get; } // other IQueryable<T> get properties } public interface IUnitOfWork { int SaveChanges(); } public class MyContext : DbContext, IQueryEntities, IUnitOfWork { // implement interfaces using EF } First question, is it a bad idea to separate out the query aspects of DbContext (IDbSets) from the command aspects (SaveChanges)? I am

问题 I am using Entity Framework 4.3 code first using an already existing database. There is a Users table that has the following columns: - UserID (int) - FirstName (string) - Surname (string) I have an association table called Impersonations . The Impersonations table is an association table between a user table and the same user table. A user can have a list of users. Here is the Impersonations table structure: - ImpersonateID (int primary key) - UserID (int FK to Users table's UserID column) -

问题 This may be a far fetched question, but is it possible to have a callback fire in an entity object, whenever a new instance of it has been loaded from the database (as part of e.g. a linq query), a call to Create or similar? The purpose of such a callback would be to convey a context, or set of initialization parameters, from the enclosing business object. 回答1: DbContext definitely doesn't have it but you can try to convert it back to ObjectContext and use: var objectContext = (

问题 Issue: Child model collection in MVC3 & Entity Framework 4.1 is being updated properly in model via Edit action but the values are not being saved in DB. Overview: - Model object Person contains object CaseRef's - Person property updates are getting saved in the DB on db.SaveChanges() but internal collection CaseRef property updates are not being saved - All values are bound/mapped correctly upon entry of HttpPost ActionResult Edit() so the model is being updated successfully from Form submit

问题 I'm working with ASP.NET MVC3 using EF and Code First. I'm writing a simple issue tracker for practice. In my Controller I have a fairly standard bit of code: [HttpPost] public ActionResult Edit(Issue issue) { if (ModelState.IsValid) { dbContext.Entry(issue).State = EntityState.Modified ..... } } Question part 1 I'm trying to get my head around how the dbcontext works - Before I've set the State on the dbContext.Entry(issue), I assume my issue object is detached. Once I set the state to be

问题 Say I have a table called Users, which contains your typical information: Id, Name, Street, City--much like in the example here: http://weblogs.asp.net/manavi/archive/2010/12/11/entity-association-mapping-with-code-first-part-1-one-to-one-associations.aspx. Among other things, this article states: "Code First has a concept of Complex Type Discovery that works based on a set of Conventions. The convention is that if Code First discovers a class where a primary key cannot be inferred, and no

问题 THE TABLES: Shop Product Category THE RELATIONSHIPS: (Shop) 1 <---> n (Categories) (Shop) 1 <---> n (Products) (Categories) n <---> n (Products) THE CASCADE DELETES: Shop ---> Categories ... I defined this using fluent API Shop ---> Products ... I defined this using fluent API Categories <---> Products ... EF 4.1 automatically defines cascade for "Category_Product" join table THE PROBLEM: Above results in a "multiple" cascade deletion path exception. POTENTIAL FIXES: Remove the

问题 After days studying EF to understand (kinda..) how it works, I finally realized that I might have a big problem. Imagine that I have two entities: Pais and UF . The relationship between them is Pais (0..1) ... (*) UF . A screenshot: http://i.imgur.com/rSOFU.jpg. Said that, consider that I have a controller called UFController and it has actions for Edit and Create , which are just fine. My views are using the EditorFor helper (or similar ones) for inputs, so when I submit the form the