自跟踪实体在我的 WCF 服务中返回不变

发布于 2024-09-10 05:16:33 字数 1575 浏览 13 评论 0原文

我在前端使用 MVP（模型视图演示器）设置了一个小型 n 层 Web 应用程序，在后端使用 WCF 服务，它与 BLL 通信，后面的 DAL 与 EF4.0 通信。这一切都工作得很好，我创建了几个都可以工作的 Get 和 Add 方法。现在我想创建几个 Update 方法。由于我使用的是 EF4.0 的自我跟踪实体 (STE)，因此我认为一切都会顺利进行，而且实施起来也会相当容易。

事实似乎并非如此。当在 Web 前端更改我的项目时，当移回 WCF 服务时，它们的状态保持不变。由于实体未更改，因此数据库中不会更新任何内容。通过这个问题： EF 4 自我跟踪实体确实没有按预期工作我读到这篇文章，其中更详细地介绍了有关在 n 层应用程序中实现 STE 的信息。 (http://msdn.microsoft.com/en-us/magazine/ee335715 .aspx) 我引用：

确保重复使用自我跟踪实体模板的在您的上生成的实体代码客户端。如果您使用代理代码由添加服务引用生成 Visual Studio 或其他一些工具，大部分情况看起来都不错，但你会发现实体实际上并不跟踪他们在客户端上的更改。

好吧，我已经设法使用以下代码创建了该服务的客户端：

var svc = new ChannelFactory<INorthwindSTEService>(
    "INorthwindSTEService")
    .CreateChannel();

这似乎工作得很好。问题是，如何在客户端获取序列化实体？在代码示例中，我看到作者使用了以下代码：

var products = new List<Product>(svc.GetProducts());
var customer = svc.GetCustomer("ALFKI");

但我看不到那些对象/实体/？？？已定义（我正在谈论客户和产品）

我已经使用使用添加服务引用创建的实体对其进行了测试>，但这似乎不起作用。返回的实体仍具有未更改状态。

我不想在前端引用 EF 实体，因为我希望将它们分开，并且在前端仅包含序列化对象。不过，如果真的有必要的话，我可能不得不这样做。

哦，在实体对象上使用 MarkAsModified() 方法确实可以很好地工作，但这更像是一种黑客行为，因为实体应该自行检查其状态。

关于如何进行有什么建议吗？我的猜测是使用 MarkAsModiefied() 方法或在我的 Web 应用程序中引用实体模型项目可能是可行的解决方法，但如果有更好的方法，我想先尝试一下。

原文

I've set up a little n-tier web application using MVP (Model View Presenter) in the front-end, a WCF service on the backend, which communicates with the BLL an behind that the DAL, which communicates with the EF4.0.
This is all working quite nicely, I've created several Get and Add methods which all work.
Now I wanted to create several Update methods. Since I'm using the Self-Tracking Entities (STE) of the EF4.0, I thought everything would work out quite fine and implementation would be rather easy.

This doesn't seem to be the case.
When changing my items in the web front-end, they keep having the status Unchanged when moving back to the WCF-service. Because the entity is unchanged, nothing gets updated in the database.
Through this question on SO: EF 4 Self Tracking Entities does not work as expected
I came accross the article telling something more in detail about implementing the STE's with in an n-tier application. (http://msdn.microsoft.com/en-us/magazine/ee335715.aspx)
I quote:

Make certain to reuse the Self-Tracking Entity template’s
generated entity code on your
client. If you use proxy code
generated by Add Service Reference in
Visual Studio or some other tool,
things look right for the most part,
but you will discover that the
entities don’t actually keep track of
their changes on the client.

Well, I've managed to create a client to the service using this code:

var svc = new ChannelFactory<INorthwindSTEService>(
    "INorthwindSTEService")
    .CreateChannel();

This appears to work quite alright.
The thing is, how do I get the serialized entities on the client?
In the code example I'm seeing the writer uses this code:

var products = new List<Product>(svc.GetProducts());
var customer = svc.GetCustomer("ALFKI");

But I fail to see where those objects/entities/??? are defined (I'm talking about a Customer and a Product)

I've tested it using the entities which were created using the Add Service Reference, but that doesn't seem to work. The returned entities still have the status Unchanged.

I'd rather not reference the EF entities in my front-end, because I'd like to keep them separated and only have serialized objects on my front-end. Though, if it is really necessary, I might just have to do that.

Oh, using the MarkAsModified() method on the entity object does work nicely though, but that's more of a hack as the entity should check his status by itself.

Any advice on how to proceed?
My guess is using the MarkAsModiefied() method or referencing the entity models project in my web application could be viable work-around, but if there's something better, I'd like to try that first.

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