public async Task <IActionResult> UpdateExchange(int id, [Bind("ID,Title")] Exchange exchange)
        {
            if (id != exchange.ID)
            {
                return(NotFound());
            }

            if (ModelState.IsValid)
            {
                try
                {
                    ExchangeUpdater.Update(_context);
                }
                catch (DbUpdateConcurrencyException)
                {
                    if (!ExchangeExists(exchange.ID))
                    {
                        return(NotFound());
                    }
                    else
                    {
                        throw;
                    }
                }
            }
            return(RedirectToAction(nameof(Index)));
        }
        public async Task <IActionResult> UpdateExchange(int?id)
        {
            if (id == null)
            {
                return(NotFound());
            }

            var exchange = await _context.Exchange
                           .FirstOrDefaultAsync(m => m.ID == id);

            if (exchange == null)
            {
                return(NotFound());
            }

            try
            {
                ExchangeUpdater.RemoveAllWatchedTokens(_context, (int)id);
                ExchangeUpdater.Update(_context);
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!ExchangeExists(exchange.ID))
                {
                    return(NotFound());
                }
                else
                {
                    throw;
                }
            }

            return(RedirectToAction(nameof(Details), new { id = exchange.ID }));
        }