如何在实体框架6.0中使用多个连接字符串 [英] How to use multiple connection string in entity framework 6.0

问题描述

我使用.net框架和使用实体框架6.0创建了一个Web API。基于代码的迁移已启用。

我有多个连接字符串（假设web.config中存在2个连接字符串），这样如果一个服务器关闭，那么Entity Framework应该使用第二个连接字符串连接到另一个服务器。 / p>

请建议我怎么做到这一点？

 
公共类DatabaseBootstrapper：IDbContextFactory< TestDBContext> 
 {
 public TestDBContext Create（）
 {
 
 //我想要一些逻辑来测试服务器是否使用第一个连接字符串，如果服务器不在，那么使用第二连接字符串。 
 TestDBContext dbcontext = null; 
 
 dbcontext = new TestDBContext（@"Data Source = .\sqlexpress3; Initial Catalog = TestDB; User ID = sa; Password = Password $; Trusted_Connection = False;"）; 
 
返回dbcontext; 
} 
 
} 
 
 

公共类TestDBContext：DbContext 
 { 
 public DbSet< Nodes>节点{get;组; } 
 public DbSet< Graphs>图表{get;组; } 
 
 
 public TestDBContext（string connectionString）
：base（connectionString）
 {
 Database.SetInitializer（new MigrateDatabaseToLatestVersion< TestDBContext，Migrations.Configuration> （））; 
} 
 
 protected override void OnModelCreating（System.Data.Entity.DbModelBuilder modelBuilder）
 {
 base.OnModelCreating（modelBuilder）; 
} 
} 

解决方案

您好agrawalamit3101，

我们可以创建一个AppSettings来实现它。我们可以更改appsettings值以连接不同的连接字符串。像这样：

< appSettings> 
< add key =" Connstr"值= QUOT;模型2" /> 
< / appSettings> 
 
< connectionStrings> 
< add name =" Model1" connectionString =" data source =（localdb）\ MSSQLLocalDB; initial catalog = EF20161102; integrated security = True; MultipleActiveResultSets = True; App = EntityFramework"的providerName = QUOT; System.Data.SqlClient的" /> 
< add name =" Model2" connectionString =" data source =（localdb）\ MSSQLLocalDB; initial catalog = Blogging; integrated security = True; MultipleActiveResultSets = True; App = EntityFramework"的providerName = QUOT; System.Data.SqlClient的" /> 
< / connectionStrings> 

#Rleated DbContext。

 public partial class Model1：DbContext 
 {
 public Model1（）
：base（" name =" + ConfigurationManager.AppSettings [" Connstr"]。ToString（）+""）
 { 
} 
 
 public virtual DbSet< Blog>博客{get;组; } 
 
 protected override void OnModelCreating（DbModelBuilder modelBuilder）
 {
} 
} 

祝你好运，

Cole Wu

I have created a Web API using .net framework and using entity framework 6.0. Code based Migration is enabled.

I have multiple connection strings (suppose 2 connection strings are present in web.config) so that if one server is down then Entity Framework should connect to another server using second connection string.

Please suggest how can I achieve this?

 public class DatabaseBootstrapper : IDbContextFactory<TestDBContext>
 {
         public TestDBContext Create()
        {
		
		    // I want some logic to test server is up or not using first connection string if server is not up then use second connection string.
            TestDBContext dbcontext = null;

            dbcontext = new TestDBContext(@"Data Source=.\sqlexpress3;Initial Catalog=TestDB;User ID=sa;Password=Password$;Trusted_Connection=False;");

            return dbcontext;
        }
}

  public class TestDBContext : DbContext
    {
        public DbSet<Nodes> Nodes { get; set; }
        public DbSet<Graphs> Graphs { get; set; }
       
      
        public TestDBContext(string connectionString)
            : base(connectionString)
        {
                       Database.SetInitializer(new MigrateDatabaseToLatestVersion<TestDBContext, Migrations.Configuration>());
        }

        protected override void OnModelCreating(System.Data.Entity.DbModelBuilder modelBuilder)
        {
             base.OnModelCreating(modelBuilder);
        }
    }

解决方案

Hi agrawalamit3101,

We could create a AppSettings to achieve it. we could change the appsettings value to connect different connectionstring. like this:

  <appSettings>
    <add key="Connstr" value="Model2" />
  </appSettings>

  <connectionStrings>
    <add name="Model1" connectionString="data source=(localdb)\MSSQLLocalDB;initial catalog=EF20161102;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient" />
    <add name="Model2" connectionString="data source=(localdb)\MSSQLLocalDB;initial catalog=Blogging;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient" />
  </connectionStrings>

#Rleated DbContext.

public partial class Model1 : DbContext
    {
        public Model1()
            : base("name="+ ConfigurationManager.AppSettings["Connstr"].ToString() + "")
        {
        }

        public virtual DbSet<Blog> Blogs { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
        }
    }

Best regards,

Cole Wu

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