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Escape underscore characters in string containing URLs for markdown – Telegram API

Given a string such as: 

"The user foo_bar has a Twitter account: https://twitter.com/foo_bar"

In order to be sent in markdown mode by the Telegram bots API, it should be formatted as:

"The user foo_bar has a Twitter account: [https://twitter.com/foo_bar]"

(Adding [] to url could be done using regex).

Is it possible to write a function in Python that can escape certain characters such as _ or * in a text, but only when these characters are not contained within a URL?

Here is an example without checking character location:

original_text = 'The user foo_bar has a Twitter account: https://twitter.com/foo_bar'
formatting_url = re.sub(
    'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*(),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+', r'[g<0>]', original_text)
escaping_char = formatting_url.replace('*', '*').replace('_', '_')
print(escaping_char)

Output:

The user foo_bar has a Twitter account: [https://twitter.com/foo_bar]

Where the _ in url is also be replaced.

Tags:

2

Answers


  1. 0

    First add brackets to the url using regex. Then you can iterate over each letter of the string, add an escape character whenever you see one when outside of a url. You can raise a flag whenever you see character [ or ] to know if you are inside a url:

    s = "The user foo_bar has a Twitter account: [https://twitter.com/foo_bar]"
in_url = False
output = ""
for letter in s:
    if letter == "[":
        in_url = True
        output += letter
    elif letter == "]":
        in_url = False
        output += letter
    elif letter == "_":
        if in_url:
            output += "_"
        else:
            output += "_"
    else:
        output += letter
print(output)
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  2. 0

    If you are using python-telegram-bot – then there is a method for escaping text (for both Markdown versions 1 and 2). If you need to add link there – propose to format it separately and concatenate these strings.

    >>> from telegram.utils.helpers import escape_markdown

>>> a = "The user foo_bar has a Twitter account: https://twitter.com/foo_bar"

>>> escape_markdown(a)
'The user foo\_bar has a Twitter account: https://twitter.com/foo\_bar'

>>> escape_markdown(a, version=2)
'The user foo\_bar has a Twitter account: https://twitter\.com/foo\_bar'
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