public async Task <IActionResult> Facture(Guid id) { var facture = _formationService.GetFactureForId(id); DateTimeOffset offset = facture.Date ?? DateTimeOffset.Now; DateTime dateFacture = offset.DateTime; string idFacture = facture.NumericId.ToString("000"); facture.NoFacture = dateFacture.ToString("'F'yy'" + "-" + "'MMdd" + "-" + idFacture); return(View(facture)); }