VCR with placeholders

some_spec.rb

use_vcr_cassette 'some/cassette', :tag => :bad_staging_api

spec_helper.rb

set_wildcards_for_response = lambda do |response|
  wildcards = {
    '<CHECK_IN>'      => %w( InDate EffectiveStartDate ),
    '<CHECK_OUT>'     => %w( OutDate EffectiveEndDate ),
    '<TOTAL_RATE>'    => %w( TotalRate )
  }

  wildcards.each do |wildcard, attributes|
    attributes.each {|attribute| response.body.gsub!(/#{attribute}\=["']([^"']+)["']/, "#{attribute}=\"#{wildcard}\"") }
  end
  response
end

replace_wildcards = lambda do |response|
  response.body.gsub!('<CHECK_IN>', Time.zone.today.to_s(:db))
  response.body.gsub!('<CHECK_OUT>', (Time.zone.today + 4.days).to_s(:db))
  response.body.gsub!('<TOTAL_RATE>', "836.00")
  response
end

VCR.configure do |c|
  include VCR::CustomPlaceholders
  c.cassette_library_dir = Rails.root.join('spec/fixtures/vcr_cassettes')
  c.hook_into :webmock
  c.default_cassette_options = { :record => :new_episodes }

  newly_recorded_bad_staging_api_request = lambda do |req|
    VCR.current_cassette &&
    VCR.current_cassette.tags.include?(:bad_staging_api) &&
    req.recordable?
  end

  #Ensure first test run applies forced test values (irrelevent content such as date)
  c.after_http_request(newly_recorded_bad_staging_api_request) do |req, res|
    set_wildcards_for_response[res]
    replace_wildcards[res]
  end

  c.before_record(:bad_staging_api) do |interaction, cassette|
    set_wildcards_for_response[interaction.response]
  end

  # Needed for subsequent test runs...
  c.before_playback(:bad_staging_api) do |interaction|
    replace_wildcards[interaction.response]
  end 
end

Perfect, i started down that path but screwed it up by putting it within the VCR.configure context, and not using the #[] syntax. Much cleaner now, and working perfectly in the app.

Example gist edited to reflect updates.