bot.send_media_group fails (python-telegram-bot)

Question

I need a handler for bot that will take a group of photos and videos, and will send them in one message along with the text to the group. The code below sends only separated messages:

def photo(update: Update, context: CallbackContext) -> None:
    global fwd_chat_id
    context.bot.send_media_group(chat_id=fwd_chat_id,
                                 media=[InputMediaPhoto(media=update.message.photo[0].file_id)])

photo_handler = MessageHandler(Filters.photo | Filters.video, photo)
dispatcher.add_handler(photo_handler)

But if I try to collect all photos first and then send them all I get "telegram.error.BadRequest: Message text is empty"

def photo(update: Update, context: CallbackContext) -> None:
    global fwd_chat_id, media_group
    if media_group == []:
        media_group.append(InputMediaPhoto(media=update.message.photo[0].file_id, caption='1'))
    else:
        media_group.append(InputMediaPhoto(media=update.message.photo[0].file_id))

photo_handler = MessageHandler(Filters.photo | Filters.video, photo)
dispatcher.add_handler(photo_handler)


def finish_photo_loading(update: Update, context: CallbackContext) -> None:
    global fwd_chat_id, media_group
    context.bot.send_media_group(chat_id=fwd_chat_id,
                                 media=media_group)

finish_handler = CommandHandler('finish', finish_photo_loading)
dispatcher.add_handler(finish_handler)

Answer 1

So my solution is to collect all sanded photos with:

context.bot_data[update.message.from_user.username + '_media']. \
append(InputMediaPhoto(media=update.message.photo[-1].file_id))

And then use send_media_group:

context.bot.send_media_group(chat_id=update.effective_chat.id,
                         media=context.bot_data[update.message.from_user.username+'_media'])

after getting command /finish