MonkeyPatch CanCan to use OUTER JOINs (requires squeel)

gistfile1.rb

require "cancan/model_adapters/active_record_adapter"

class CanCan::ModelAdapters::ActiveRecordAdapter
  # use squeel's symbol-predicates to convert all joins into outer joins
  # see https://github.com/ryanb/cancan/issues/374
  def clean_joins(joins_hash)
    joins = []
    joins_hash.each do |name, nested|
      name = name.outer if nested.is_a? Hash
      joins << (nested.empty? ? name : {name => clean_joins(nested)})
    end
    joins
  end

end