EF 5在运行时更改连接字符串 [英] EF 5 Changing Connection String at Runtime

问题描述

好的，我想重新创建一个使用EF 4.1到EF 5.0创建的项目，足够简单或至少我想。我的旧项目中的一件事是，我可以在运行时在EF 4.1中更改数据库连接字符串：

 使用（var myContext = new MyEntities（ConnectionString））
 {
 
} 
  

  string connectionString =data source = LocalHost;初始目录= MyDatabase;用户id = MyUserName; password = MyPassword; multipleactiveresultsets = True; App = EntityFramework; 
 
 using（var myContext = new MyEntities（））
 {
 myContext.Database.Connection.ConnectionString = connectionString; 
} 
  

现在，我花了两个多小时的时间，我想我的问题是这是在运行时更改连接字符串的正确方法吗？如果是这样做的原因呢？

我找到了这个 Link ，但它没有起作用。我收到了Ladislav Mrnka的第一个答案的第一个评论中详细的错误。后来我发现这个链接，似乎工作正常。

更新

我重新阅读了第一个链接我发布了，我发现另一个解决方案，我只是创建了一个部分类：

  public partial class MyEntities：DbContext 
 {
 public MyEntities（string connectionString）：base（connectionString）
 {
数据库.Connection.ConnectionString = connectionString; 
} 
} 
  

解决方案

使用将连接字符串作为参数的上下文构造函数重载。

Ok, I want to recreate a project that I created using EF 4.1 to EF 5.0, simple enough or at least I thought. One of the things in my old project is that I was able to change the database connection string at runtime in EF 4.1:

using (var myContext = new MyEntities(ConnectionString))
{

}

Easy-peasy but in EF 5.0 you have to do this differently:

string connectionString = "data source=LocalHost;initial catalog=MyDatabase;user id=MyUserName;password=MyPassword;multipleactiveresultsets=True;App=EntityFramework";

using (var myContext = new MyEntities())
{
         myContext.Database.Connection.ConnectionString = connectionString;
}

Now, this took me a better part of two hours to figure out, so I guess my question is this the proper way of changing the connection string at runtime or not? If it is why did they make this change?

I did find this Link but it didn't work. I received the error as detailed in the first comment of the first answer by Ladislav Mrnka. I later found this Link which seems to work fine.

UPDATE

I re-read the first link I posted and I found another solution, I simply created a partial class:

public partial class MyEntities : DbContext
{
    public MyEntities(string connectionString) : base(connectionString) 
    {
          Database.Connection.ConnectionString = connectionString; 
    }
}

解决方案

Use the context constructor overload that take the connection string as a parameter.

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