使用实体框架中的输出参数执行SQL存储过程

Question

使用EF,我正在尝试执行一个返回单个字符串值的存储过程,即SQL代理作业的状态.

存储过程声明为

CREATE PROCEDURE [dbo].[up_GetJobStatus](@JobStatus NVARCHAR(30) OUTPUT)
AS

-- some code omitted for brevity

SELECT @JobStatus = (
SELECT  
    CASE job_state 
    WHEN 1 THEN 'Executing'
    WHEN 2 THEN 'Waiting for thread'
    WHEN 3 THEN 'Between retries'
    WHEN 4 THEN 'Idle'
    WHEN 5 THEN 'Suspended'
    WHEN 6 THEN '<unknown>'
    WHEN 7 THEN 'Performing completion actions'
END
FROM @xp_results results 
INNER JOIN msdb.dbo.sysjobs sj
ON results.job_id = sj.job_id
WHERE sj.job_id = @job_id)

RETURN

我已验证存储过程是否正常,因为我可以在查询窗口中执行它并返回

    @JobStatus
  ------------
  1|Idle

但是,在使用EF执行时,param值为NULL

var param = new SqlParameter
{
    ParameterName = "@JobStatus",
    DbType = DbType.String,
    Size = 30,
    Direction = System.Data.ParameterDirection.Output
};

var result = this.etlContext.Database.SqlQuery<string>("EXEC dbo.up_GetJobStatus @JobStatus OUTPUT", param);

我也尝试过这种ExecuteSqlCommand方法但是也没用.

有任何想法吗？

Answer 1

1. 在数据库中创建存储过程

   CREATE PROCEDURE [dbo].myStoredProcName
       @inputParam1 VARCHAR(150),
       @inputParam2 VARCHAR(150),
       @myOutputParamBool BIT OUTPUT,
       @myOutputParamString VARCHAR(100) OUTPUT,
       @myOutputParamInt INT OUTPUT
   AS
   BEGIN
       -- sql here
   END
   

2. 从数据库更新实体模型以包括存储过程 ,如下所示

3. 从C#代码调用存储过程

   System.Data.Entity.Core.Objects.ObjectParameter myOutputParamBool=new System.Data.Entity.Core.Objects.ObjectParameter("myOutputParamBool",typeof(bool));
   System.Data.Entity.Core.Objects.ObjectParameter myOutputParamString=new System.Data.Entity.Core.Objects.ObjectParameter("myOutputParamString",typeof(string));
   System.Data.Entity.Core.Objects.ObjectParameter myOutputParamInt=new System.Data.Entity.Core.Objects.ObjectParameter("myOutputParamInt",typeof(Int32));
   
   using (var context = new SandCryptEntities())
   {
       context.myStoredProcName(inputParam1, inputParam2, myOutputParamBool, myOutputParamString, myOutputParamInt);   
   }
   
   bool myBool = Convert.ToBoolean(myOutputParamBool.Value);
   string myString = Convert.ToString(myOutputParamString.Value);
   int myInt = Convert.ToInt32(myOutputParamInt.Value);
   

Answer 2

这是一个实际的答案。显然，当您首先使用 DbContext/code 时，实体框架中的输出参数存在严重问题。本文有很好的讨论和解决方法：http://weblogs.asp.net/dwahlin/using-entity-framework-code-first-with-stored-procedures-that-have-output-parameters。显然它应该通过更新来“修复”，但我还没有真正看到这种情况发生。