使用FromSql方法（Linq）的实体框架核心输出参数在存储过程中不起作用

Question

I am trying to get output value from the dbcontext using the method FromSql(...) .

If i execute it on SSMS, it works but not working in EF core.

My SP param:

  @totalItems VARCHAR(MAX) OUTPUT 

I've removed other params for readable and point out the issue. The records are coming but the OUTPUT parameter is always null .

Linq

IQeryable<T> = _context.Set<T>().FromSql("Sp_Todo @totalItems OUTPUT", // i also tried with OUT or without both Out/Output but no luck
 new SqlParameter("@totalItems", SqlDbType.Varchar)
 { Direction = ParameterDirection.Output});

Answer 1

I don't' have access to your whole code, but nothing ever gets executed against your queryable source until you try to enumerate it. So, probably it didn't run the Stored Procedure when you tried to get the OUTPUT.

To force immediate query evaluation you can do it:

 IQueryable<T> foo = _context.Set<T>().FromSql("Sp_Todo @totalItems OUTPUT", new SqlParameter("@totalItems", SqlDbType.Varchar) { Direction = ParameterDirection.Output });
 //totalItems output still null
 var bar = foo.ToList()
 //totalItems output not null anymore

Here's how I'm doing it:

var _companyCode = new SqlParameter("CompanyCode", "HST");
var _sMsg = new SqlParameter("sMsg", "")
{
    Direction = ParameterDirection.Output,
    SqlDbType = SqlDbType.VarChar
};

var sql = "exec temp_get_company @CompanyCode, @sMsg OUTPUT";

var result = context.Set<Company>().FromSql(sql, _companyCode, _sMsg).ToList();

var yourOutput = _sMsg.Value.ToString();