使用实体框架更新主键值 [英] Update primary key value using entity framework

问题描述

我想从实体框架内更新复合主键的一个值，我收到此错误：该物业客户ID是对象的关键信息的一部分，并不能修改

I'm trying to update one value of a compound primary key from within the entity framework and I'm getting this error: "The property 'CustomerID' is part of the object's key information and cannot be modified. "

下面是我的code：

Dim customer As Customer = (From c In db.Customer Where c.CustomerID = "xxx" AndAlso c.SiteKey = siteKey).FirstOrDefault
customer.CustomerID = "fasdfasdf"
db.SaveChanges()

这似乎太简单了。这是真的，你不能更新实体框架内的一个主键？我找不到话题的任何文件。谢谢！

It seems too simple. Is it true you can't update a primary key within the entity framework? I can't find any documentation on the topic. Thanks!

推荐答案

您不能有很好的理由。见KM意见。

You can't and for good reason. See KM comments.

有一件事情我说你可以做的是有两个表之一，匿名数据，一个他们登录后，存储的真正的用户数据。

One thing I say you could do is have two tables one with anonymous data and one that stores the the real user data after they log in.

或者你可以（而不是测试或曾经由我完成的）是有这种表的布局：

Or your could (not tested or ever done by me) is have this kind of table layout:

---Customers----
AutoNumber PK <- This links to all other tables in your database, and does NOT change.
CustomerID  <- This can change.
CustomerType <- Anonymous or logged in.

和登录时更改CustomerType和客户ID到你所需要的。

And when they log in you change the CustomerType and CustomerID to what you need.

所以，您的查询可能看起来是这样的：

So your query could look like this:

Dim customer As Customer = (From c In db.Customer _
                            Where c.CustomerID = {Some temp ID} _
                            AndAlso c. CustomerType = "Anonymous").FirstOrDefault
// After user logs in.
customer.CustomerID = {Make a new user ID here}
customer.CustomerType = "LoggedIn" {or what ever}
db.SaveChanges()

请注意，自动编号主键永远的变化。这是为了让你在与客户表的关系，任何表仍能正常工作，并且没有做对主键的（这就像刺向自己用铅笔眼）级联更新。

Note that the autonumber primary key never changes. This is so that any tables that you have in a relationship with the Customers table still work and don't have to do cascading updates on the primary key (which is like stabbing yourself in the eye with a pencil).

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