如何用Ruby Telegram Bot访问Contact对象的phone_number字段？

I'm trying to implement a Telegram bot that requests a user's phone number and performs operations on it. Here's my Ruby code:

Telegram::Bot::Client.run(token) do |bot|
  bot.listen do |message|
    case message
    when Telegram::Bot::Types::CallbackQuery
    when Telegram::Bot::Types::Message
      case message.text
      when '/help'
        bot.api.send_message(
          chat_id: message.chat.id,
          text: 'Display help.'
        )
      end
      if message.contact.phone_number == "1111111" #undefined method
        bot.api.send_message(
          chat_id: message.chat.id,
          text: 'Number received.'
        )
      end
    else
      bot.api.send_message(
        chat_id: message.chat.id,
        text: 'Unknown command.'
      )
    end
  end
end

I can get the Contact object, but when accessing the phone_number field, I get an "undefined method" error. How do I correctly access this field using the Telegram Bot Ruby wrapper library?

The error you're seeing is almost certainly because not all Message objects have a contact attribute—only messages where the user explicitly sends a contact will have this value set. For regular text messages (like /help), message.contact is nil, so calling .phone_number on it throws the undefined method 'phone_number' for nil:NilClass error.

Here's how to fix this:

1. Check if the contact exists first #

Before accessing phone_number, verify that message.contact is not nil. You can do this in a few ways:

Option 1: Use a presence check

Telegram::Bot::Client.run(token) do |bot|
  bot.listen do |message|
    case message
    when Telegram::Bot::Types::CallbackQuery
      # Handle callback queries here if needed
    when Telegram::Bot::Types::Message
      case message.text
      when '/help'
        bot.api.send_message(
          chat_id: message.chat.id,
          text: 'Display help.'
        )
      end

      # Only process if a contact was sent
      if message.contact.present?
        if message.contact.phone_number == "1111111"
          bot.api.send_message(
            chat_id: message.chat.id,
            text: 'Number received.'
          )
        else
          bot.api.send_message(
            chat_id: message.chat.id,
            text: "Got your number: #{message.contact.phone_number}"
          )
        end
      end
    else
      bot.api.send_message(
        chat_id: message.chat.id,
        text: 'Unknown command.'
      )
    end
  end
end

Option 2: Use Ruby's safe navigation operator (&.)

If you're using Ruby 2.3 or newer, the safe navigation operator lets you safely access nested attributes without checking for nil first:

if message.contact&.phone_number == "1111111"
  bot.api.send_message(
    chat_id: message.chat.id,
    text: 'Number received.'
  )
end

This will return nil (instead of throwing an error) if message.contact is nil, so the condition will simply fail silently.

2. Verify the Contact object's attributes #

For the telegram-bot-ruby library, the Telegram::Bot::Types::Contact class does have a phone_number attribute that maps directly to the Telegram API's phone_number field. As long as you're working with a valid Contact instance (not nil), this attribute will be available.

The key fix here is ensuring you only attempt to access phone_number when a contact has actually been sent by the user.

内容的提问来源于stack exchange，提问作者Carrein