in receive_file': undefined method file_id' for nil:NilClass (NoMethodError)

[unurgunite]

Hi! I'm writing a bot in Ruby for academic purposes and I'm stuck due to not knowing how to property work with the library and Telegram API itself, guess. My code is down below:

class Bot # :nodoc:
  attr_writer :token

  def initialize(token)
    @token = token
  end

  def receive_file(bot, message)
    file_id = message.document.file_id
    bot.api.get_file(chat_id: message.chat.id, file_id: file_id)
  end

  def start
    ::Telegram::Bot::Client.run(@token) do |bot|
      bot.listen do |message|
        case message.text
        when "/start"
          bot.api.send_message(chat_id: message.chat.id, text: "Hello, #{message.from.first_name}")
        when "/file"
          bot.api.send_message(chat_id: message.chat.id, text: "Send me file up to 20MB")
          receive_file(bot, message)
        when "/stop"
          bot.api.send_message(chat_id: message.chat.id, text: "Bye, #{message.from.first_name}")
        else
          p message
        end
      end
    end
  end
end

So, the problem lies in receive_file field, which throws the following error: in `receive_file': undefined method `file_id' for nil:NilClass (NoMethodError).
What did I do to get this result? I started a new Bot instance and typed a /file command and, expectedly, the program crashes with the above error. But if I just send a file to my bot, it will execute else condition branch, which is not surprising, cos the message does not fall under the pattern matching, but if I send the command in the same message along with the document, the code also execute else branch, what is now surprising for me. So, in my case I can only put all my logic of receiving a file under the else condition, what is not well and it seems to be a "code smell". All of the above aside, I'd like to wonder if there are any event handlers in the library for waiting on a document? I have the similar code, written in Python, which works well:

from pyrogram import Client, filters
import config

app = Client(session_name="Test", bot_token=config.TOKEN, api_id=config.api_id, api_hash=config.api_hash)

@app.on_message(filters.command("file"))
def get_document(client, msg):
    app.send_message(msg.chat.id, text="Send me a file")
    msg.download()
    app.send_message(msg.chat.id, text="Your file is downloading to server")

app.run()

There I send command /file with file and the document is downloading by the bot.
So, any ideas or solution for my problem?

[ivanovaleksey]

Hi, could you dump what a message looks like when you send the command along with a document?

[unurgunite]

Hi! Thanks for your reply. The message object contains the following information:

#<Telegram::Bot::Types::Message:0x000000012b0ba8e8 @message_id=2949, @from=#<Telegram::Bot::Types::User:0x000000012b0ba870 @id=123456789, @is_bot=false, @first_name="Foo", @last_name="Bar", @username="MyUserName", @language_code="ru", @can_join_groups=nil, @can_read_all_group_messages=nil, @supports_inline_queries=nil>, @chat=#<Telegram::Bot::Types::Chat:0x000000012b0ba370 @id=123456789, @first_name="Foo", @last_name="Bar", @username="MyUserName", @type="private", @title=nil, @all_members_are_administrators=nil, @photo=nil, @description=nil, @invite_link=nil, @pinned_message=nil, @permissions=nil, @slow_mode_delay=nil, @sticker_set_name=nil, @can_set_sticker_set=nil>, @date=1642352474, @text=nil, @entities=[], @sender_chat=nil, @forward_from=nil, @forward_from_chat=nil, @forward_from_message_id=nil, @forward_signature=nil, @forward_sender_name=nil, @forward_date=nil, @reply_to_message=nil, @via_bot=nil, @edit_date=nil, @media_group_id=nil, @author_signature=nil, @caption_entities=[#<Telegram::Bot::Types::MessageEntity:0x000000012b0b9740 @offset=0, @length=5, @type="bot_command", @url=nil, @user=nil, @language=nil>], @audio=nil, @document=#<Telegram::Bot::Types::Document:0x000000012b0b9a38 @file_name="Fuji.heic", @mime_type="image/heic", @thumb=#<Telegram::Bot::Types::PhotoSize:0x000000012b0b9998 @file_id="AAMCAgADGQEAAguFYeRPWepJ_ZwkC_3VBJ2_gGBNFSIAAgYTAAJaAAEhS_HPp29zf95DAQAHbQADIwQ", @file_unique_id="AQADBhMAAloAASFLcg", @file_size=6815, @width=320, @height=208>, @file_id="BQACAgIAAxkBAAILhWHkT1nqSf2cJAv91QSdv4BgTRUiAAIGEwACWgABIUvxz6dvc3_eQyME", @file_unique_id="AgADBhMAAloAASFL", @file_size=9239516>, @animation=nil, @game=nil, @photo=[], @sticker=nil, @video=nil, @voice=nil, @video_note=nil, @caption="/file", @contact=nil, @dice=nil, @location=nil, @venue=nil, @poll=nil, @new_chat_members=[], @left_chat_member=nil, @new_chat_title=nil, @new_chat_photo=[], @delete_chat_photo=nil, @group_chat_created=nil, @supergroup_chat_created=nil, @channel_chat_created=nil, @message_auto_delete_timer_changed=nil, @migrate_to_chat_id=nil, @migrate_from_chat_id=nil, @pinned_message=nil, @invoice=nil, @successful_payment=nil, @connected_website=nil, @passport_data=nil, @proximity_alert_triggered=nil, @voice_chat_started=nil, @voice_chat_ended=nil, @voice_chat_participants_invited=nil, @reply_markup=nil>

Not the most presentable view, but it turns out the only way, unfortunately

[ivanovaleksey]

I guess you could have dumped it as JSON but never mind.
Well, we can text=nil meanwhile caption=/file. I am not very much into Python but I can see this line. It kind of makes sense now, right? :)
I guess you could try doing something similar in your Ruby code