实体框架 - 数据库首先没有配置 [英] Entity Framework - Database First without config

问题描述

我正在开发一个使用EF处理现有数据库的类库。我想避免类库（和.exe或网站）的消费者在* .config文件中具有Entity连接字符串。我想要连接字符串设置一个运行时间。

如何使用Database First方法设置连接字符串？没有构造函数重载，它接受一个连接字符串，当我创建一个（在一个单独的部分类中）时，我得到一个无意识代码优先异常。

链接：

• 有没有办法先改变数据库中的连接字符串？关于修改配置文件中的连接字符串（我想避免的）也是因为它会回收进程（在Web应用程序的情况下）


• 如何在没有App.config的情况下使用Entity Framework 。不好，因为它使用ObjectContext，我需要在导入数据库时​​生成的上下文。

解决方案

DbContext上有一个构造函数，它需要一个DbConnection，你需要使用一个EntityConnection对象：

  SqlConnectionStringBuilder sqlBuilder =新的SqlConnectionStringBuilder（）; 
 
 //设置数据源的属性。 
 sqlBuilder.DataSource =server name; 
 sqlBuilder.InitialCatalog =数据库名称; 
 sqlBuilder.IntegratedSecurity = true; 
 
 //构建SqlConnection连接字符串。 
 string providerString = sqlBuilder.ToString（）; 
 
 var entityBuilder = new EntityConnectionStringBuilder（）; 
 
 //初始化EntityConnectionStringBuilder。 
 //设置提供者名称。 
 entityBuilder.Provider =System.Data.SqlClient; 
 
 //设置特定于提供者的连接字符串。 
 entityBuilder.ProviderConnectionString = providerString; 
 
 //设置元数据位置。 
 entityBuilder.Metadata = @res：//*/Model1.csdl | res：//*/Model1.ssdl | res：//*/Model1.msl; 
 
 using（var context = new YourDbContext（entityBuilder.ToString（）））{
 // do stuff here 
} 
  / pre> 
 
 
要注意的重要事项是元数据部分 - Model1显然需要替换为您的型号名称。
 
 
 
参考： http://msdn.microsoft.com/en- us / library / bb738533.aspx  
 
 
 
编辑20/02/2013 22:25 
 
 
 
所以作为一个添加，你需要扩展创建的DbContext类与一个部分类，添加一个构造函数来支持上述代码，如下所示：
 code> public partial class YourDbContext 
 {
 public YourDbContext（string connection）：base（connection）{} 
} 
  
此类需要与由实体框架向导生成的DbContext相同的命名空间。
 
I'm developing a class library that deals with an exiting db using EF. I want to avoid the consumer of the class library (and .exe or a web site) to have in the *.config file the Entity connection string. I want the connection string set a run-time.

How do I set the connection string with Database First approach? There is no constructor overload that takes a connection string and when I created one (in a separate partial class) I got an "UnintentionalCodeFirstException".

I have reviewed already the following links:


Is there a way to change connection string in database first?. Its about modifying the connection string in the config file, which I want to avoid, also because it would recycle the process (in the case of a web app)
How can l use Entity Framework without App.config. Not good because it uses ObjectContext and I need the context generated when I imported the database.

解决方案
There is a constructor on DbContext that takes a DbConnection, and you need to use an EntityConnection object for it:
SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder();

// Set the properties for the data source.
sqlBuilder.DataSource = "server name";
sqlBuilder.InitialCatalog = "database name";
sqlBuilder.IntegratedSecurity = true;

// Build the SqlConnection connection string.
string providerString = sqlBuilder.ToString();

var entityBuilder = new EntityConnectionStringBuilder();

// Initialize the EntityConnectionStringBuilder.
//Set the provider name.
entityBuilder.Provider = "System.Data.SqlClient";

// Set the provider-specific connection string.
entityBuilder.ProviderConnectionString = providerString;

// Set the Metadata location.
entityBuilder.Metadata = @"res://*/Model1.csdl|res://*/Model1.ssdl|res://*/Model1.msl";

using(var context = new YourDbContext(entityBuilder.ToString())){
    //do stuff here
}
The important thing to note is the metadata part - "Model1" obviously needs to be replaced for your model name.

Ref: http://msdn.microsoft.com/en-us/library/bb738533.aspx

EDIT 20/02/2013 22:25

So as an addition you'll need to extend the created DbContext class with a partial class that adds a constructor to support the above code, like this:
public partial class YourDbContext
{
    public YourDbContext(string connection) : base(connection) {}
}
This class needs to be in the same namespace as the DbContext that is generated by the entity framework wizard.

                        
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