public IHttpActionResult GetUsers([FromUri] string senderID) { List <IUser> result = new List <IUser>(); if (!LoggedUsers.Contains(senderID)) { return(Content(HttpStatusCode.Unauthorized, "Not logged in.")); } //other rights? try { (DbAdmin.GetAll()).ToList().ForEach(a => result.Add(a)); (DbCustomer.GetAll()).ToList().ForEach(c => result.Add(c)); (DbDriver.GetAll()).ToList().ForEach(d => result.Add(d)); } catch (Exception e) { Trace.Write($"Error on 'GetUsers()'. Error message: {e.Message}"); Trace.Write($"[STACK_TRACE] {e.StackTrace}"); return(InternalServerError(e)); } return(Ok(result)); }