如何通过Entity Framework启用SQL应用程序角色

Question

我正在使用Entity Framework开发大型政府应用程序。一开始我遇到了一个关于启用SQL应用角色的问题。使用ADO.NET，我使用以下代码：

SqlCommand cmd = new SqlCommand("sys.sp_setapprole");
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Connection = _sqlConn;
            SqlParameter paramAppRoleName = new SqlParameter();
            paramAppRoleName.Direction = ParameterDirection.Input;
            paramAppRoleName.ParameterName = "@rolename";
            paramAppRoleName.Value = "AppRole";
            cmd.Parameters.Add(paramAppRoleName);

            SqlParameter paramAppRolePwd = new SqlParameter();
            paramAppRolePwd.Direction = ParameterDirection.Input;
            paramAppRolePwd.ParameterName = "@password";
            paramAppRolePwd.Value = "123456";
            cmd.Parameters.Add(paramAppRolePwd);

            SqlParameter paramCreateCookie = new SqlParameter();
            paramCreateCookie.Direction = ParameterDirection.Input;
            paramCreateCookie.ParameterName = "@fCreateCookie";
            paramCreateCookie.DbType = DbType.Boolean;
            paramCreateCookie.Value = 1;
            cmd.Parameters.Add(paramCreateCookie);

            SqlParameter paramEncrypt = new SqlParameter();
            paramEncrypt.Direction = ParameterDirection.Input;
            paramEncrypt.ParameterName = "@encrypt";
            paramEncrypt.Value = "none";
            cmd.Parameters.Add(paramEncrypt);

            SqlParameter paramEnableCookie = new SqlParameter();
            paramEnableCookie.ParameterName = "@cookie";
            paramEnableCookie.DbType = DbType.Binary;
            paramEnableCookie.Direction = ParameterDirection.Output;
            paramEnableCookie.Size = 1000;
            cmd.Parameters.Add(paramEnableCookie);

            try
            {
                cmd.ExecuteNonQuery();
                SqlParameter outVal = cmd.Parameters["@cookie"];
                // Store the enabled cookie so that approle  can be disabled with the cookie.
                _appRoleEnableCookie = (byte[]) outVal.Value;

            }
            catch (Exception ex)
            {
                result = false;
                msg = "Could not execute enable approle proc." + Environment.NewLine + ex.Message;
            }

但无论我怎么搜索，都找不到在EF上实现的方法。

另一个问题是：如何将应用程序角色添加到实体数据模型设计器中？

---

我正在使用以下代码执行EF参数：

AEntities ar = new AEntities();

            DbConnection con = ar.Connection;
            con.Open();
            msg = "";
            bool result = true;
            DbCommand cmd = con.CreateCommand();

            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Connection = con;
            var d = new DbParameter[]{
            new SqlParameter{ ParameterName="@r", Value ="AppRole",Direction =  ParameterDirection.Input}
          , new SqlParameter{ ParameterName="@p", Value ="123456",Direction =  ParameterDirection.Input}
           };
            string sql = "EXEC " + procName + " @rolename=@r,@password=@p";
            var s = ar.ExecuteStoreCommand(sql, d);

当运行ExecuteStoreCommand时，该行会返回错误：

应用程序角色只能在临时级别激活。

- Ehsan Farahani

---

你尝试过使用ObjectContex.ExecuteStoreCommand()吗？你需要传递一个字符串，例如'EXEC sys.sp_setapprole @rolename, @password, @fCreateCookie, ...'，并传递SqlParameters以提供命令中参数占位符的值。 - Pawel

Answer 1

我会以下方式进行操作（假设使用数据库优先）：

1. I create the DbContext from the db and call it MyEntitiesBase

2. I inherit from MyEntitiesBase to create MyEntities with the following code:

   public partial class MyEntities : MyEntitiesBase
   {
   
   private byte[] appRoleCookie;
   
   private void SetAppRole()
   {
       try
       {
           appRoleCookie = Database.SqlQuery<byte[]>(
               @"
               DECLARE @cookie VARBINARY(8000)
               DECLARE @r INT
               EXEC sp_setapprole 'user', 'pass', @fCreateCookie = true, @cookie = @cookie OUTPUT
               SELECT @cookie").First();
       }
       catch
       {
           throw new AuthenticationException();
       }
   }
   
   private void UnSetAppRole()
   {
       bool failed = Database.SqlQuery<bool>("DECLARE @result BIT; EXEC @result = sp_unsetapprole @cookie = " + appRoleCookie.ToHexadecimalString() + "; SELECT @result").First();
       if (failed)
           throw new SecurityException();
   }
   
   public MyEntities() : base()
   {
       Database.Connection.Open();
       SetAppRole();
   }
   
   private bool disposed = false;
   
   protected override void Dispose(bool disposing)
   {
       if (disposed)
           return;
       UnSetAppRole();
       Database.Connection.Close();
       disposed = true;
       base.Dispose(disposing);
   }
   }
   

ToHexadecimalString 是一个扩展方法，适用于 IEnumerable<byte>，如下所示：

public static class BytesExtensions
{
    public static string ToHexadecimalString(this IEnumerable<byte> bytes)
    {
        return "0x" + string.Concat(bytes.Select(b => b.ToString("X2")));
    }
}

就是这样。在连接池开启的情况下，一切都能正常工作。您只需使用这个继承版本，而不是由EF生成的版本。

- Nahuel Prieto

---

我刚刚在EF6中使用IDbConnectionInterceptor实现了这段代码，效果非常好。在“Opened”方法中调用“SetAppRole”，在“Closing”方法中调用“UnSetAppRole”。谢谢。 - Duncan Howe

Answer 2

基本上你正在调用存储过程。

实体框架具有执行存储过程的功能。这里附带一个视频解释：http://msdn.microsoft.com/en-us/data/gg699321.aspx

如果您向下滚动到“使用导入函数映射存储过程”部分，您将找到与您相关的部分。

- Shiraz Bhaiji