public async Task <IActionResult> Add([FromBody] ItemAddModel model)
 {
     if (!ModelState.IsValid)
     {
         return(BadRequest(ModelState.GetErrorList()));
     }
     try
     {
         await _manager.AddAsync(model);
     }
     catch (Exception ex)
     {
         return(BadRequest(ex.Message));
     }
     return(Ok());
 }