如何使用Ruby / Rails在字符串中查找特定单词

Question

I got a few string like so:

TFjyg9780878_867978-DGB097908-78679iuhi698_widesky_light_87689uiyhk

AND

TFjyg9780878_867978-DGB097908-78679iuhi698_sky_light_87689uiyhk

AND

TFjyg9780878_867978-DGB097908-78679iuhi698_widesky_dark_87689uiyhk

AND

TFjyg9780878_867978-DGB097908-78679iuhi698_sky_dark_87689uiyhk

I need to check whether the strings above has one of the widesky_light , sky_light , widesky_dark and sky_dark with exactitude so I wrote this:

if my_string.match("widesky_light")
  ...
end 

For each variant, but the problem I'm having is because sky_light and widesky_light are similar, my code is not working properly. I believe the solution to the above would be a regex, but I've spend the afternoon yesterday trying to get it to work without much success.

Any suggestions?

EDIT

A caveat: in this string (as example): TFjyg9780878_867978-DGB097908-78679iuhi698_widesky_light_87689uiyhk , the part after widesky_light , which is _87689uiyhk is optional, meaning that sometimes I have it, sometimes I don't, so a solution would not be able to count on _string_ .

Answer 1

Looks like you just need to reorder your if statements

if my_string.match(/widesky_light/)
  return 'something'
end
if my_string.match(/sky_light/)
  return 'something'
end

Answer 2

Maybe something like this:

case my_string
when /_(sky_light)/
  # just sky_light
when /sky_light/
  # widesky_light
when /_(sky_dark)/
  # just sky_dark
when /sky_dark/
  # widesky_dark
else
  puts "I don't like"
end

Answer 3

Regex

1st regex : extract word for further checking

Here's a regex which only matches the interesting part :

(?<=_)[a-z_]+(?=(?:_|\b))

It means lowercase word with possible underscore inside, between 2 underscores or after 1 underscore and before a word boundary . If you need some logic depending on the case (widesky, sky, light or dark), you could use this solution.

Here in action.

2nd regex : direct check if one of 4 words is present

If you just want to know if any of the 4 cases is present :

(?<=_)(?:wide)?sky_(?:dark|light)(?=(?:_|\b))

Here in action, with either _something_after or nothing.

Case statement

list = %w(
  TFjyg9780878_867978-DGB097908-78679iuhi698_widesky_light_87689uiyhk
  TFjyg9780878_867978-DGB097908-78679iuhi698_sky_light_87689uiyhk
  TFjyg9780878_867978-DGB097908-78679iuhi698_widesky_dark_87689uiyhk
  TFjyg9780878_867978-DGB097908-78679iuhi698_sky_dark_87689uiyhk
  TFjyg9780878_867978-DGB097908-78679iuhi698_trash_dark_87689uiyhk
)

list.each do |string|
  case string
  when /widesky_light/ then puts "widesky light found!"
  when /sky_light/     then puts "sky light found!"
  when /widesky_dark/  then puts "widesky dark found!"
  when /sky_dark/      then puts "sky dark found!"
  else                      puts "Nothing found!"
  end
end

In this order, the case statement should be fine. widesky_dark won't match twice, for example.