Having trouble with a search and replace using regular exrpession in Rails

Question

I'm using Rails 4.2.3. I am trying got replace a parameter in my URL with the same value but adding “1” to it. So for instance if my URL is

http://replace.mydomein.com/profiles/152/expanded?embed=true&page=2

I would want the result after the substitution to be

http://replace.mydomein.com/profiles/152/expanded?embed=true&page=3

So I'm trying this

url = url.sub(/(\&<=page=)\d+/) {|m| m.to_i+1}

but it is having no effect on my URL. Passing “ http://replace.mydomein.com/profiles/152/expanded?embed=true&page=2 ” as an argument yields the same result. What am I doing wrong in my regular expression above?

Answer 1

You only need to replace the \\& in your regex to ?

url = url.sub(/(?<=page=)\d+/) { |m| m.to_i.next }

Because the syntax for a positive lookbehind (?<= is like that.