如何使用 Pomelo ORM 为 .net core 的 MySQL 存储过程传递输出参数

Question

这是我在 MySQL

中的 SP

CREATE PROCEDURE `GetMemberID`(
   IN uname     VARCHAR(128),
   OUT MemberID     INT
)
BEGIN  
   SELECT ID INTO MemberID FROM `Member` Where username = uname;    
END

我正在从使用 Pomelo ORM 的 .netcore web api 项目调用 SP。

var usernameParam = new MySqlParameter
{ 
   ParameterName = $"@uname",
   DbType = DbType.String,
   Direction = ParameterDirection.Input,
   Value = "test"
 };
var memberIDParam = new MySqlParameter
{ 
   ParameterName = $"@MemberID",
   DbType = DbType.Int32,
   Direction = ParameterDirection.Output
 };

rContext.Database.ExecuteSqlRaw($"Call GetMemberID (@uname=@uname, @MemberID=@MemberID OUT)"
            , usernameParam , memberIDParam);

使用输出参数时出现以下错误。

Only ParameterDirection.Input is supported when CommandType is Text (parameter name: @MemberID)

如何传递输出参数？

Answer 1

a known issue 在 github 中，正如 mguinness 评论的那样

RelationalCommand.csdon't specify CommandType so it'll default to CommandType.Text which means output parameters won't work.

这里有一个解决方法，你可以参考

 using (MySqlConnection lconn = new MySqlConnection(Configuration.GetConnectionString("DefaultConnection")))                
            {
                lconn.Open();
                using (MySqlCommand cmd = new MySqlCommand())
                {
                    cmd.Connection = lconn;
                    cmd.CommandText = "GetMemberID"; // The name of the Stored Proc
                    cmd.CommandType = CommandType.StoredProcedure; // It is a Stored Proc

                    cmd.Parameters.AddWithValue("@uname", "sherry");
                    cmd.Parameters.Add("@MemberID", MySqlDbType.Int32);
                    cmd.Parameters["@MemberID"].Direction = ParameterDirection.Output; // from System.Data
                    cmd.ExecuteNonQuery();
                    Object obj = cmd.Parameters["@MemberID"].Value;
                    var lParam = (Int32)obj;    // more useful datatype

                }
            }

参考：

如何使用 Pomelo ORM 为 .net core 的 MySQL 存储过程传递输出参数

How to pass the output parameter for MySQL stored procedure for .net core using Pomelo ORM

mysql

asp.net-core-webapi

pomelo-entityframeworkcore-mysql