带正则表达式的gsub删除一个字符

Question

I have an article model (article.rb):

class Article < ActiveRecord::Base
  attr_accessible :name, :content
end

I have a gsub like this in my article.rb:

self.content.gsub!(/anylink[^']/i, "<%= link_to 'anylink', 'http://website.com/anylink' %>")

This substitutes the word "anylink" in the text of an article with the "link_to 'anylink', 'http://website.com/anylink'" to create an automatic link. When there is already a "link_to..." , it will NOT substitute since I excluded the ' after anylink in the regular expression.

It works, but the problem is that it deletes the next character following "anylink" . Eg it converts:

"Have a look at anylink and see"

to

"Have a look at anylinkand see"

"anylink" in this second phrase now is a hyperlink, so everything is fine except the missing space that has been deleted during the gsub operation. Any ideas why and how I can avoid this?

Answer 1

String#gsub replaces the whole matching part of your pattern with your replacement, which is here the anylink string and one character which is not an apostrophe.

So it would replace the following Strings for example:

• anylinkA
• anylink.
• anylink!

If you want to keep your character, you could create a match and put that after the replacement:

self.content.gsub!(/anylink([^'])/i, "<%= link_to 'anylink', 'http://website.com/anylink' %>\\1")

Here the matching group ([^']) will match on the character and the escaped \\1 will put that char after your replacement.

But I recommend you to use the \\b to match the word boundary :

self.content.gsub!(/\banylink\b/i, "<%= link_to 'anylink', 'http://website.com/anylink' %>")

So with this solution the word anylink will be replaced by the gsub and it can be preceded or followed any character but not an alphanumeric.

If you want to replace all matches in self.content , add g regexp modifier:

self.content.gsub!(/\banylink\b/ig, "<%= link_to 'anylink', 'http://website.com/anylink' %>")