Ruby regular expression to get users names after @ symbol

Question

How can I get the username without the @ symbol? That's everything between @ and any non-word character.

message = <<-MESSAGE
From @victor with love,
To @andrea,
and CC goes to @ghost
MESSAGE

Using a Ruby regular expression, I tried

username_pattern = /@\w+/

I will like to get the following output

message.scan(username_pattern)
#=> ["victor", "andrea", "ghost"]

The [twitter-text](https://github.com/twitter/twitter-text) gem can [extract](https://github.com/twitter/twitter-text/tree/master/rb#extraction) @-mentions. — Stefan, Sep 19 '18 at 13:52
Still waiting for an answer that is deserving of the green checkmark? — Cary Swoveland, Oct 24 '19 at 05:57

score 3 · Answer 1 · answered Sep 19 '18 at 06:45

3

Use look behind

(?<=@)\w+

this will leave @ symbol regex

answered Sep 19 '18 at 06:45

Nambi_0915

At the moment this is the best answer which fulfils the requirements. Can you please explain the `?<=` in the regex? Thank you. – victorhazbun Sep 19 '18 at 06:54
1

`?<=` is the look behind operator. It matches from the character next to it and not itself. `\w+` will match the words or digits continuously without any space or anyother special characters – Nambi_0915 Sep 19 '18 at 06:57
2

Best to be precise. `(?<=@)` is a *positive* look-behind expression. It means that the string `"@"` must immediately precede the match that follows, but is not part of the match. `\w+` matches a sequence of one or more *word characters*, namely, letters (uppercase or lowercase), digits or underscores (`"_"`). – Cary Swoveland Sep 19 '18 at 07:20

spickermann · Answer 2 · 2018-09-19T06:52:41.700

1

I would go with:

message.scan(/(?<=@)\w+/)
#=> ["victor","andrea","ghost"]

You might want to read about look-behind regexp.

edited Sep 19 '18 at 06:52

answered Sep 19 '18 at 06:47

spickermann

It also matches the `,` at the end in `andrea,` – Nambi_0915 Sep 19 '18 at 06:48
I believe we don't want to include the `,`. – victorhazbun Sep 19 '18 at 06:49
@victorhazbun, but you wrote in the question: _everything between @ and space_. – spickermann Sep 19 '18 at 06:49
Thanks @spickermann, I just updated the SO question description. Sorry. – victorhazbun Sep 19 '18 at 06:51
1

@victorhazbun: Updated my answer to address your updated question. – spickermann Sep 19 '18 at 06:53
@spickermann thanks for pointing out the "look-behind regexp" link. – victorhazbun Sep 19 '18 at 06:55

score 1 · Answer 3 · answered Sep 19 '18 at 06:55

1

You could match the @ and then capture one or more times a word character in a capturing group

@(\w+)

username_pattern = /@(\w+)/

answered Sep 19 '18 at 06:55

The fourth bird

score 0 · Answer 4 · answered Sep 19 '18 at 08:07

0

Try this

irb(main):010:0> message.scan(/@(\w+)/m).flatten
=> ["victor", "andrea", "ghost"]

answered Sep 19 '18 at 08:07

anjali rai

4 Answers4