将POCO映射到实体框架中的实体 [英] Mapping POCO to Entity in Entity Framework

问题描述

我使用EF for Visual Studio 2008，所以我没有与EF集成POCO。

由于我们有一个n层应用程序，我们正在映射POCO到实体不断，实体不会被抛到上层，我用Automapper进行映射，手动也是。

我们遇到的大问题是从POCO映射到

如果我添加了一个与现有实体有关系的新实体（例如为现有客户添加新帐户）我有现有的实体POCO，需要从数据库获取相关实体（例如客户端），这只是一个非常慢的。

我的问题是：

如何创建一个实体，正确附加到上下文以及所有这些，从POCO对象，没有调用数据库？

解决方案

设置 EntityKey 而不是加载相关的obj从数据库（注意，有一个更好的方法来做这个在EF 4;这是为EF 1）：

  var account = new EntityAccount 
 {
 Name = pocoAccount.Name ，
 //等
}; 
 //现在而不是做account.Client = Context.Clients.Where（... 
 account.ClientReference.EntityKey = 
 new EntityKey（MyEntities.Clients，Id pocoAccount.Client.Id）; 
  

根本没有DB访问。

I use EF for Visual Studio 2008, so I don't have POCO integration with EF.

Since we have a n-tier application, we're mapping POCO to entities constantly, entities aren't thrown to the upper layers, I do mapping with Automapper and manually also.

The big problem we have is when mapping from POCO to entities.

If I'm adding a new entity that has a relationship with existing entities (e.g. adding a new Account for an existing Client), I have the existing entity POCO, and it's needed to get the related entities (e.g. the Client) from the database, this is just something very slow.

And there is my question:

How can I create an entity, properly attached to the context and all that, from a POCO object, without making any call to the database?

解决方案

Set the EntityKey instead of loading the related object from the DB (note there's a better way to do this in EF 4; this is for EF 1):

var account = new EntityAccount
              {
                  Name = pocoAccount.Name,
                  // etc.
              };
// now instead of doing account.Client = Context.Clients.Where(...
account.ClientReference.EntityKey = 
    new EntityKey("MyEntities.Clients", "Id", pocoAccount.Client.Id);

This does no DB access at all.

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