挂钩IDbInterceptor到EntityFramework DbContext只有一次 [英] Hooking IDbInterceptor to EntityFramework DbContext only once

问题描述

IDbCommandInterceptor 界面没有很好的记录。我只发现了一些稀缺的教程：

The IDbCommandInterceptor interface is not very well documented. And I've only found a few scarce tutorials on it:

• http://www.entityframeworktutorial.net/entityframework6/database-command-interception.aspx


• https://msdn.microsoft.com /en-us/data/jj556606%28v=vs.113%29.aspx


• https://entityframework.codeplex.com/wikipage?title=Interception


• https://www.tutorialspoint.com/entity_framework/entity_framework_command_interception.htm


• < a href =https://msdn.microsoft.com/en-us/data/dn469464%28v=vs.113%29.aspx =nofollow noreferrer> https://msdn.microsoft.com/en-us/data/dn469464%28v=vs.113%29.aspx

• http://www.entityframeworktutorial.net/entityframework6/database-command-interception.aspx
• https://msdn.microsoft.com/en-us/data/jj556606%28v=vs.113%29.aspx
• https://entityframework.codeplex.com/wikipage?title=Interception
• https://www.tutorialspoint.com/entity_framework/entity_framework_command_interception.htm
• https://msdn.microsoft.com/en-us/data/dn469464%28v=vs.113%29.aspx

还有几个问题：

• 实体框架6 - 计时查询


• 获取来自实现IDbCommandInterceptor的DbContext

• Entity Framework 6 - Timing queries
• Getting DbContext from implementation of IDbCommandInterceptor

这些是挂钩我的建议发现：

These are the suggestions on hooking I've found:

1 - 静态 DbInterception 类：

DbInterception.Add(new MyCommandInterceptor());

2 - 在中执行上述建议DbConfiguration class

2 - Doing the above suggestion in a DbConfiguration class

public class MyDBConfiguration : DbConfiguration {
    public MyDBConfiguration() {
        DbInterception.Add(new MyCommandInterceptor());
    }
}

3 - 使用配置文件：

3 - Using the config file:

<entityFramework>
  <interceptors>
    <interceptor type="EFInterceptDemo.MyCommandInterceptor, EFInterceptDemo"/>
  </interceptors>
</entityFramework>

---

虽然我无法弄清楚如何勾DbContext的 DbConfiguration 类，并且在配置方法的类型中也没有。 另一个我发现的例子似乎建议你写一个记录器的命名空间：

---

Although I couldn't figure out how to hook the DbConfiguration class to the DbContext, and neither what to put in the type part of the config method. Another example I found seemed to suggest that you write the namespace of a logger:

type="System.Data.Entity.Infrastructure.Interception.DatabaseLogger, EntityFramework"

我注意到 DataBaseLogger 实现 IDisposable ， IDbConfigurationInterceptor 和

IDbInterceptor 。 IDbCommandInterceptor 还实现 IDbInterceptor ，所以我尝试（没有成功）格式化如下：

I noted that DataBaseLogger implements IDisposable, IDbConfigurationInterceptor and
IDbInterceptor. IDbCommandInterceptor also implements IDbInterceptor, so I tried (without success) to format it like this:

type="DataLayer.Logging.MyCommandInterceptor, DataLayer"

当我直接调用静态 DbInterception 类时，每次调用都添加了另一个拦截器。所以我的快速肮脏的解决方案是利用静态构造函数：

And when I called the static DbInterception class directly, it added another interceptor every call. So my quick and dirty solution was to utilize static constructors:

//This partial class is a seperate file from the Entity Framework auto-generated class,
//to allow dynamic connection strings
public partial class MyDbContext // : DbContext
{
    public Guid RequestGUID { get; private set; }

    public MyDbContext(string nameOrConnectionString) : base(nameOrConnectionString)
    {
        DbContextListeningInitializer.EnsureListenersAdded();

        RequestGUID = Guid.NewGuid();
        //Database.Log = m => System.Diagnostics.Debug.Write(m);
    }

    private static class DbContextListeningInitializer
    {
        static DbContextListeningInitializer() //Threadsafe
        {
            DbInterception.Add(new MyCommandInterceptor());
        }
        //When this method is called, the static ctor is called the first time only
        internal static void EnsureListenersAdded() { }
    }
}

但是什么是正确/预期的方法？

But what are the proper/intended ways to do it?

推荐答案

我发现我的 DbContext 类只需要具有 DbConfigurationType 属性，在运行时附加一个配置：

I figured out that my DbContext class just needed to have the DbConfigurationType attribute, to attach a configuration at runtime:

[DbConfigurationType(typeof(MyDBConfiguration))]
public partial class MyDbContext // : DbContext
{
    public MyDbContext(string nameOrConnectionString) : base(nameOrConnectionString)
    { }
}

public class MyDBConfiguration : DbConfiguration {
    public MyDBConfiguration() {
        this.AddInterceptor(new MyCommandInterceptor());
    }
}

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