entity-framework-4

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 I'm a big fan of using the Repository pattern to return IQueryable<T> objects. I then let my services layer determine what does what (eg. filter by XXX, order by YYY, project into ABCD, etc). But I've got some hardcore DB stuff, so I've got it all wrapped up into a Stored Procedure . Works fine. I know EF can execute stored procs .. but I'm not sure how this fits into a Repository Pattern data layer. Does anyone have any examples / suggestions ? Do i let the repository method execute the

问题 I'm trying to buid a site with the following: VS 2010 (for the updated WCF RIA Services) Silverlight 4.0 (packaged with WCF RIA Services). MVC 2 EF 4.0 I am setting it up so that the public facing pages will be html from MVC, but the administration portion will be a silverlight navigation application using using WCF RIA Services for data access. When I create the silverlight application within a webforms application, it works (I am able to add a datagrid and retrieve data using EF 4.0 and WCF

问题 So I'm trying to create a generic select by ID method for a base repository class. In order to achieve this I'm using EF4 with POCO's. I created an interface with a getter called Id and successfully modified the T4 template in order to have a generic Id property in all the entities that returns the PK. The problem comes when I use the query. I'm implementing it like this: public virtual T GetByID(int id) { return Database.ObjectSet<T>().SingleOrDefault(entity => entity.Id == id); } And even

问题 I am using EF4 in my application and I want to make test cases for DAL methods, which generally hit the database to get data. I am using the Typemock framework for Mocking. I want to mock database call and only want to test queries. E.g.: ObjectContext.Where(u => u.code == Code) For doing this, I need to make Fake ObjectContext for EF Models and want to fill some fake data in Fake ObjectContext so that we can execute our queries (LINQ) on fake ObjectContext . Kindly suggest how can I can

问题 Hi I am binding a WPF textbox to an Entity Framework property as follows: <TextBox Grid.Column="1" Grid.Row="0" Margin="5,2" Text="{Binding Path=MyEntityObject.SizeLower, Mode=TwoWay}" /> It binds fine to the property and when I change it, it saves to the DB as expected. But if I delete the content of the Textbox I get the red error border around it. I dont have any validator in place so I am guessing the texbox is complaining about the value not being nullable. But in fact this property in

问题 I'm trying to streamline my existing repos by using a generic repo I can subclass from. The problem is that I can't figure out how to write a few of my base class methods. I currently have: public interface IRepository<T> : IDisposable where T : class { IQueryable<T> GetAll(); T GetSingle(int id); T GetSingle(string slug); void Save(T entity); } public class HGRepository<T> : IRepository<T> where T : class { protected HGEntities _siteDB; protected IObjectSet<T> _objectSet; public HGRepository

问题 Overview I am using entity framework 4.3 code first with the fluent interface to setup my DbContext. I have a base Item class with other types that inherit this such as an Event , BlogPost , ForumThread , WikiPage and so on. These inherited types are mapped with what I think entity framework refers to as TPT inheritance. This works great when querying a single type like 'events' or 'blog posts' but constructs very complicated queries with horrible performance when trying to query across all

问题 This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center. Closed 7 years ago . Having bumped into the of the lack of enum property support in Entity Framework 4 I discovered this article which describes a workaround: Entity

问题 What I am trying to do is basically what NHibernate does when you do something like: var instance = session.Get<Customer>(id, LockMode.Upgrade); I need to lock the entity row in the database. Why I need that? Imagine something like a workflow instance that can be updated by multiple actors(people or processes) at the same time. The constraints I have don't allow for optimistic locking solutions. 回答1: EF doesn't have support for this. If you want to lock some record by query you must do