如何将Connection String中的"Provider Name"添加到Context文件中？

Question

我正在使用Entity Framework 5 Code-first approch.这是我的Context文件:

using IMS.Domain.Inventory;
using IMS.Domain.Security;
using IMS.Domain.StoredProcedures;
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Data.Objects;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace IMS.Domain.DBContext
{
    public class IMSDBContext : DbContext
    {
        public DbSet<ModuleAccounting> ModuleAccountings { get; set; }
        public DbSet<ModuleInfo> ModuleInfos { get; set; }
        public DbSet<ModuleType> ModuleTypes { get; set; }
        public DbSet<UserAccounting> UserAccountings { get; set; }
        public DbSet<UserGroup> UserGroups { get; set; }
        public DbSet<UserInfo> UserInfos { get; set; }


    //
    // set a connection string

    public IMSDBContext()  // Constructor of the Context
    {
        this.Database.Connection.ConnectionString =
            "Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=IMSDB;Data Source=.\\SQLExpress";
    }
}

}

这里我在构造函数中添加了连接字符串.但有没有办法将"提供者名称"添加到连接字符串？

Answer 1

您是否有特殊原因要在db上下文中对连接字符串进行硬编码.通常它应该存储在配置文件中.您可以在配置文件中指定提供程序,并从上下文中引用连接字符串.这将解决您的问题.

 public MyDbContext()
        : base("Name=MyDbContext")
    {
    }

并在您的配置文件中

<connectionStrings>
    <add name="MyDbContext" connectionString="data source=.\sqlexpress;initial catalog=YourDbName;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient"/>
  </connectionStrings>

Answer 2

是:您可以准备一个DbConnection类型,该类型可以传递给由底层提供程序构建并正确构建连接字符串的DbContext.

所以要在CODE中实现这个连接字符串...见下文

<connectionStrings>
    <add name="MyCTX" connectionString="Data Source=localhost;Initial Catalog=MYDB ;Integrated Security=True;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient" />
  </connectionStrings>

回想一下,DBContext有一个重载的构造函数

 public DbContext(DbConnection existingConnection, bool contextOwnsConnection)

所以你只需要由底层工厂提供商构建的Dbconnection.看到

 public interface IDbConnectionFactory

这3种类型所包含的内容:

System.Data.Entity.Infrastructure.SqlCeConnectionFactory System.Data.Entity.Infrastructure.LocalDbConnectionFactory System.Data.Entity.Infrastructure.SqlConnectionFactory

所以这是一个使用SQLConnectionFactory的例子.返回一个DBConnection.哪个可以传递给DBContext.您可以在编程休闲时重复/更改或变量.对于其他2个提供商.

 public DbConnection GetSqlConn4DbName(string dataSource, string dbName) {
        var sqlConnStringBuilder = new SqlConnectionStringBuilder();
        sqlConnStringBuilder.DataSource = String.IsNullOrEmpty(dataSource) ? DefaultDataSource : dataSource;
        sqlConnStringBuilder.IntegratedSecurity = true;
        sqlConnStringBuilder.MultipleActiveResultSets = true;
        // NOW MY PROVIDER FACTORY OF CHOICE, switch providers here 
        var sqlConnFact = new SqlConnectionFactory(sqlConnStringBuilder.ConnectionString);
        var sqlConn = sqlConnFact.CreateConnection(dbName);
        return sqlConn;
    }