Cleaning parameters from string url in Ruby

10 May 12

Today I had to make sure that a url wasn’t containing a certain parameter, and if it was I needed to clean it form the params.

Let’s assume a resource like

* RESOURCE
  * url

When saving that resource I need to make sure that the a param ‘user_ref’ is not present from the url. This param can or cannot have values.

So we start with a simple test

require 'spec_helper'

describe Resource do

  describe 'cleaning user_ref param' do

     before do 
        @empty_param = FactoryGirl.create(:resource, :url => "http://google.com?param1=1&clickref=¶m3")
        @full_param      = FactoryGirl.create(:resource, :url => "http://google.com?param1=1&clickref=remove-me¶m3")
        @clean_url        = FactoryGirl.create(:resource, :url => "http://google.com?param1=1")
     end

    it "should remove empty click ref params and keep other params" do
       @empty_param.url.should eql("http://google.com?param1=1¶m3")
    end

    it "should remove full click ref params and keep other params" do
       @full_param.url.should eql("http://google.com?param1=1¶m3")
    end

    it "should still save url without click ref params and keep other params" do
       @clean_url.url.should eql("http://google.com?param1=1")
    end

  end
end

After testing different Regexps (and I have to admin I’m not a master of them, so maybe the solution is somewhere else), I finally found Addressable Gem and everything became easy again.

EDIT: Theo Cushion sent me a better cleaner solution via email, please check the bottom of the post

In the Resource model I have

class Resource < ActiveRecord::Base

....

before_save :clean_clickref

....

protected

def clean_clickref

  if self.url
      require 'addressable/uri'

      uri = Addressable::URI.parse(self.url)
      params = uri.query_values

      if params
        uri.query_values = params.except('clickref')
        self.url = uri.to_s
      end

    end
  end

end

EDIT: This is Theo Cushion’s solution, using the url setter. Way nicer, and we don’t need the :before_save

class Resource < ActiveRecord::Base
  ....
  def url=(value)
    require 'addressable/uri'
    result = if value.is_a? String
      uri = Addressable::URI.parse value
      uri.query_values = uri.query_values.except( 'clickref' ) if uri.query_values

      uri.to_s
    else
      nil
    end

    write_attribute :url, result
  end
  ....
end

This is easy enough and readable enough and make the tests pass, time for the next feature!

Nicolas Alpi

Technical Director

Occasional hiker and sheep enthusiast who loves playing and exploring with his kids.

Nicolas Alpi

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