What's the "ruby way" to parse a string for a single key/value?

Question

I am trying to parse a multi line string and get the rest of the line following a pattern.

text:

hello john
your username is: jj
thanks for signing up

I want to extract jj, aka everything after "your username is: "

One way:

text = "hello john\nyour username is: jj\nthanks for signing up\n"
match = text[/your username is: (.*)/]
value = $1

But this reminds me of perl... and doesn't "read" as naturally as I am told ruby should.

Is there a cleaner way? AKA A "ruby" way?

Thanks

Answer 1

The split command is mindbogglingly useful. It divides a string into an array of substrings, separating on whatever you pass in. If you don't give it any arguments, it splits on whitespace. So if you know the word you're looking for is the fifth "word" (splitting on both spaces and the return character), you can do this:

text = "hello john\nyour username is: jj\nthanks for signing up\n"
match=text.split[5]

..but perhaps that's not sufficiently self-documenting, or you want to allow for multi-word matches. You could do this instead:

midline=text.split("\n")[1]
match=midline.split("username is: ").last

Or perhaps this more terse way:

match=text[/username is: (.*)/,1]

Answer 2

Your code is pretty much the Ruby way. If you don't want to use the global $1, you can use the 2 arg version String#[]:

match = text[/your username is: (.*)/, 1]

Answer 3

Not sure if it's any more Ruby'ish, but another option:

>> text = "hello john\nyour username is: jj\nthanks for signing up\n"
>> text.match(/your username is: (.*)/)[1]
=> "jj"

Answer 4

There's also Regexp#match, which returns a MatchData object, which has all the information you could possibly want.

irb> match = /your username is: (.*)/.match "hello john\nyour username is: jj\nthanks for signing up\n"
#=> #<MatchData:0x557f94>
irb> match.pre_match
#=> "hello john\n"
irb> match.post_match
#=> "\nthanks for signing up\n"
irb> match[0]
#=> "your username is: jj"
irb> match[1]
#=> "jj"