应用程序生成错误：必须在Web Api 2中声明标量变量。此外，有关WebApi2中的代码和调试Controller方法的实践

Question

I asked a lot in here, as I am new to MVC, WebApi and RestService.

So, I am working with an application where StoredProcedure is being called inside Controller, but getting Error :

Must Declare Scalar Variable @empid

Code is below :

    [HttpGet]
    [Route("~/api/Login/{EmpID}/{pwd}")]
            public IHttpActionResult ValidateLoginDetails(string EmpID, string pwd)
    {


        int a=0;
        if (EmpID == null)
            EmpID = "";
        else a = Int32.Parse(EmpID);

        if (pwd == null)
            pwd = "";

        var val = new  SqlParameter()
        {ParameterName="@val",Direction=ParameterDirection.Output,SqlDbType=SqlDbType.Int};

        var e = new SqlParameter("@empid", SqlDbType.Int) ;
        e.Value = a;
        //User.Identity.Name;
        var y = new SqlParameter("@pwd", SqlDbType.VarChar);
        y.Value = pwd;

        using (var x = new DB_BgCheckEntities()) 
        {
            var retVal = x.Database.SqlQuery<IEnumerable<int>>
            ("Exec proc_Bgcheck_login @empid,@pwd,@val out", e, y, val);

           // var ret = retVal.Single();
            //foreach(var ab in retVal)
            //{
            //    Console.WriteLine(ab.ToList());
            //}
            //retVal.ToList();
            x.Database.ExecuteSqlCommand("Exec proc_Bgcheck_login @eid,@pwd,@val out", e, y, val);
            if ((int)val.Value == 1)
            {
                return Ok(1);
            }
            else return NotFound();

        }
        }

Below statement is doing my work, but I am not getting why the dbcontext is not working

  x.Database.ExecuteSqlCommand("Exec proc_Bgcheck_login @eid,@pwd,@val out", e, y, val); 

Stored Proc :

CREATE PROCEDURE proc_Bgcheck_login
(
    @emp_no int,
    @pwd varchar(255),
    @val int output
)as
BEGIN
    SET @val=0;
    DECLARE @count int;
    SELECT @count=COUNT(*) FROM tbl_User_Login where [Emp No]=@emp_no and [Password]=@pwd;
    IF (@count = 1)
        BEGIN
            SET @val=1;
            RETURN @val;
        END
    ELSE
        RETURN @val;
END
GO

Few questions, I need to ask :

1. Is it good practice, to call StoredProc inside GetMethod, like I did.
2. How to implement the DTO(Data Transfer Object) for this method? I googled down, but didn't got the concept for that.
3. Debugging method inside Controller, how to do that line by line ?

PS : For the error, I went through different sites and threads of StackOverflow, but none resolved my solution.

Answer 1

The error :

Must declare Scalar Variable @empid is resolved .

As mentioned by @amit, I haven't passed the parameters for the @empid and @pwd .

So, the correct way to pass the parameter was :

var retVal = dbcontext.Database.SqlQuery<tbl_User_Login>
            ("Exec proc_Bgcheck_login @empid,@pwd,@val ",e,y, val).ToList();

Thanks.