I am very new to learning APS.NET Core Web API and I am having trouble with a result I am getting from a stored procedure I am running using FromSqlRaw

I have a class for input:

public class DevInput
{
   public string DevID { get; set;}
   public int Source { get; set;}
}

and I have a class for output:

public class DevOutput
{
   public string Name{ get; set;}
   public string Cost { get; set; }
   public string OrdQty { get; set;}
   public string Model { get; set}
}

I am mapping the return from a SQL stored procedure to said class with:

public class DevOutputController : ControlleBase
{
   private readonly DevContext _context;

   public DevOutputContoller(DevContext context)
   {
      _context = context
   }

   [HttpPost]
   public async Task<ActionResult<IEnumerable<DevOutput>>> GetOutput(DevInput input)
   {
      string sp = "Exec DevSearch '" + input.DevID + "', " + input.Source + ""
   
      return await _context.DevOutput.FromSqlRaw(sp).ToListAsync
   }
}

This is working fine except sometimes the “Cost” returned from the stored procedure is a decimal type, and sometimes a string type depending on what sql table the “Cost” value is retrieved from

I am wondering if there is a way that I can convert whatever is returned from the stored procedure to a string so that it can properly be mapped to my output class