Regex in Ruby: expression not found

Question

I'm having trouble with a regex in Ruby (on Rails). I'm relatively new to this.

The test string is: http://www.xyz.com/017010830343?$ProdLarge$

I am trying to remove "$ProdLarge$". In other words, the $ signs and anything between.

My regular expression is: \$\w+\$

Rubular says my expression is ok. http://rubular.com/r/NDDQxKVraK

But when I run my code, the app says it isn't finding a match. Code below:

some_array.each do |x|
   logger.debug "scan #{x.scan('\$\w+\$')}"
   logger.debug "String? #{x.instance_of?(String)}"

   x.gsub!('\$\w+\$','scl=1')

   ...

My logger debug line shows a result of "[]". String is confirmed as being true. And the gsub line has no effect.

What do I need to correct?

You're passing a string containing a regex instead of an actual regex. — Dave Newton
– Dave Newton, Commented Jan 14, 2013 at 20:13

Nikita Kouevda · Accepted Answer · 2013-01-14 20:11:41Z

5

Use /regex/ instead of 'regex':

> "http://www.xyz.com/017010830343?$ProdLarge$".gsub(/\$\w+\$/, 'scl=1')
=> "http://www.xyz.com/017010830343?scl=1"

answered Jan 14, 2013 at 20:11

Nikita Kouevda

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the Tin Man · Accepted Answer · 2013-01-15 01:26:57Z

2

Don't use a regex for this task, use a tool designed for it, URI. To remove the query:

require 'uri'

url = URI.parse('http://www.xyz.com/017010830343?$ProdLarge$')
url.query = nil

puts url.to_s
=> http://www.xyz.com/017010830343

To change to a different query use this instead of url.query = nil:

url.query = 'scl=1'

puts url.to_s
=> http://www.xyz.com/017010830343?scl=1

URI will automatically encode values if necessary, saving you the trouble. If you need even more URL management power, look at Addressable::URI.

edited Jan 15, 2013 at 1:26

answered Jan 15, 2013 at 1:21

the Tin Man

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2 Comments

bigwinner Over a year ago

thanks. I didn't realize URI was so handy. In this particular app, I believe need to use some form of regex because the queries can actually get a lot more complex than the example here. But I'll apply this somewhere.

the Tin Man Over a year ago

We can't help you unless you show accurate examples of what you're up against. Add your other examples to your original question by editing it.

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