EF并发处理与模式第一种方法时间戳属性 [英] EF Concurrency Handling with Timestamp attribute in Model First approach

问题描述

我试图实施<特定的解决方案href="http://www.asp.net/mvc/tutorials/getting-started-with-ef-using-mvc/handling-concurrency-with-the-entity-framework-in-an-asp-net-mvc-application"相对=nofollow>处理并发实体框架在ASP.NET MVC应用程序。

文章说：

在模型\ Department.cs，添加一个跟踪属性：

Adding a Tracking Property to the Department Entity

In Models\Department.cs, add a tracking property:

[Timestamp] 
public Byte[] Timestamp { get; set; }

     

时间戳属性指定此列将包括更新的Where子句中，并删除发送到数据库的命令。

The Timestamp attribute specifies that this column will be included in the Where clause of Update and Delete commands sent to the database.

由于我使用的型号第一个的办法，我也跟着步骤1 - 5中的创建一个时间戳列实体框架

Since I'm using a model first approach, I followed steps 1 - 5 outlined in Creating a Timestamp column with Entity Framework

1. 添加一个名为时间戳属性的实体EF模型
2. 设置类型为二进制
3. 设置为空的假
4. 设置StoreGeneratedPattern式来计算
5. 设置ConcurrencyMode为固定

当我从数据库模型更新我的code时，模型\ Department.cs现在包含

When I update my code from the database model, the Models\Department.cs now contains

    public virtual byte[] Timestamp
    {
        get;
        set;
    }

然后我用了元数据类指定时间戳属性：

Then I used the metadata class to specify the Timestamp attribute:

// Metadata for Department entity
public class DepartmentMetadata
{
    [Timestamp]
    public byte Timestamp { get; set; }
}

Q1。我测试是否时间戳值列正在发生变化的情况下排的编辑。事实并非如此。

Q1. I tested whether the value of the Timestamp column is changing in case of row edits. It isn't.

修改1 的问题造成的，因为SQL Server列类型是二，它应该是类型时间戳。改变数据类型固定timestamp列的问题没有得到更新。

EDIT 1 The problem was caused because the SQL Server column type was binary, where it should have been of type timestamp. Changing the data type fixed the issue of the Timestamp column not getting updated.

Q2。我试图修改同一个实体（使用打开新的标签），以查看是否 OptimisticConcurrencyException 被抛出。事实并非如此。我究竟做错了什么？请帮助我了解，谢谢。

Q2. I was trying to modify the same entity (using "Open in new tab") to see if an OptimisticConcurrencyException is thrown. It isn't. What am I doing wrong? Please help me understand, thanks.

推荐答案

的问题造成的，因为我有每个HTTP会话只有一个ObjectContext的，所以打开一个新的标签和测试，将不会引起并发异常。

The problem was caused because I had one ObjectContext per HTTP session, and so opening a new tab and testing it would NOT cause a concurrency exception.

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