entity-framework-4

问题 I am converting linq2sql to entity framework. During the conversion I needed to convert the loadwith of linq2sql with include for eagar loading, but the eager loading is not working. When I used the profiler, I found that the child entities are loaded with they are accessed. DataBaseEntities context = new V3C_DataBaseEntities(); context.Agents.Include("Account"); Agent ag = context.Agents.Where(x => x.Login_ID == "2").SingleOrDefault(); // here the account should have been loaded, // but

问题 i am Trying to fit in breezeJS with my existing architecture. I have a structure like html/JS/Angular :: based view using hot-towel angular. web api controllers :: whom the view calls. Services layer :: that is being called from Web api. Any business logic goes here. Unit of Work :: And (if) business logic requires to talk to data base for CRUDs it calls UOW. Repository Pattern :: UOW is actually wrapping repositories. and repositores in turn talking to DbContexts. Uptill now i was able to

问题 I am trying to use transactions with EF4 Code-first with an unit of work implementation. Is there a reason we cannot use Connection.BeginTransaction from the context ? It is only intended to be used in SQL transactions only ? Because when im calling it i get the error : Illegal operation. Connection is closed. Thanks. 回答1: Part of the answer will be that DbContext.SaveChanges() is automatically transactional, so in many cases, you will not need to roll your own transactions. What is your

问题 I just started using Entity Framework and it created a Context class which I can use to get all the data i need from it. But I am facing an issue on how I should organize my code, by watching the demos, the person just uses the framework and codes everything on a console application. What is the best way to use Entity Framework and that it looks clean?, what I mean by this is...right now using aspx pages, I could just use the aspx.cs to get the data or save the data. But I do not want this, I

问题 I'm currently using DbContext with Ef 4.1, and I'm trying to audit all changes some of my entities. I can capture the original and current values for any Properties of an entity, however I cannot figure out how to capture the association (Foreign Key) OriginalValues of a NavigationProperty. Has anyone figured this out? 回答1: You must either include foreign keys to your entities so they will be tracked as normal values or you must convert your DbContext to ObjectContext and use more powerful

问题 I am developing MVC application using EF 4.0. I am trying to put value , <test> to the address field but while saving its gives an below error , how to solve it ? A potentially dangerous Request.Form value was detected from the client (Address=" <test> "). Edit Please check below code namespace CEntities { [MetadataType(typeof(EmployeeMetaData))] public partial class Employee { } /// <summary> /// Holds the validations for Employee class /// </summary> public class EmployeeMetaData { [Key]

问题 A trick to avoiding filtering by nullable parameters in SQL was something like the following: select * from customers where (@CustomerName is null or CustomerName = @CustomerName) This worked well for me in LINQ to SQL: string customerName = "XYZ"; var results = (from c in ctx.Customers where (customerName == null || (customerName != null && c.CustomerName == customerName)) select c); But that above query, when in ADO.NET EF, doesn't work for me; it should filter by customer name because it

问题 While executing a stored procedure created in SQL Server 2008 R2 in SQL Server 2012 and retrieving the data through an Entity Data Model, this error occurs: The version of SQL Server in use does not support datatype 'datetime2' The stored procedure is executing successfully in SQL Server Management Studio 2012. But the issue is when coming back to the Entity Data Model. Anyone encountered this kind of an issue?? 回答1: What is the compatibility level of that database you're running against?

问题 I am going to start a new project and i want to try EF model first and i want to be able to work with a development database in MSSQL and have an production database in MySQL. Is there anyone out there with experience in this? Is this possible? I have read about Entity Designer Database Generation Power Pack . Does it support this? I want it to be simple to add columns and table created to the model to both my production (MySQL) and development database. 回答1: This will not work because type

问题 I have a simple database with 2 main tables with a many to many relationship through a 3rd bridge/join table. This 3rd table has an extra field besides the two keys required, so that Entity Framework transforms it into a full entity rather than a many to many relationship between the other 2 tables. I cannot change this third table in the database itself. Is there a way to ignore the extra field so that EF can do what I want, or a way to manually transform the bridge table into a many to many