ransack.rb

# Patch for ransack (https://github.com/ernie/ransack) to use scopes
# Helps migrating from Searchlogic or MetaSearch
# Place this file into config/initializer/ransack.rb of your Rails 3.2 project
#
# Usage:
#   class Debt < ActiveRecord::Base
#     scope_ransackable :overdue
#     scope :overdue, lambda { where(["status = 'open' AND due_date < ?", Date.today]) }
#   end
#
#   Ransack out of the box ignores scopes. Example:
#     Debt.search(:overdue => true, :amount_gteq => 10).result.to_sql
#      => "SELECT `debts`.* FROM `debts` AND (`debts`.`amount` >= 10.0)"
#
#   This is changed by the patch. Example:
#     Debt.search(:overdue => true).result.to_sql
#     => "SELECT `debts`.* FROM `debts`  WHERE `debts`.`status` = 'open' AND (due_date < '2012-11-23') AND (`debts`.`amount` >= 10.0)"
#
#   Only scopes that return ActiveRecord::Relation are supported.
#   Any other scope or method that is called via Ransack will throw an exception
#   and cause a database transaction rollback.
#
module Ransack
  class ScopeNotWhitelistedError < StandardError; end

  module Adapters
    module ActiveRecord
      module Base
        def scope_ransackable(*args)
          @ransackable_scopes ||= []
          @ransackable_scopes  += args.map(&:to_sym).reject { |scope| scope == :scope_ransackable }
          
          # make the custom scopes available in view, so that we can use view helpers
          # e.g. f.select :my_field instead of select_tag 'q[my_field]'
          # note: that means we need to override with :selected => value
          args.each do |method|
            Ransack::Search.define_method method do
              nil
            end
          end
        end

        def scope_is_ransackable?(scope)
          @ransackable_scopes ||= []
          @ransackable_scopes.include? scope.to_sym
        end

        def search_with_scopes(params = {}, options = {})
          ransack_scope = self
          ransack_params = {}

          # Extract params which refer to a scope
          transaction do
            (params||{}).each_pair do |k,v|
              if ransack_scope.respond_to?(k)
                if !scope_is_ransackable? k
                  raise ScopeNotWhitelistedError.new
                elsif (v == true)
                  ransack_scope = ransack_scope.send(k)
                else
                  ransack_scope = ransack_scope.send(k, v)
                end
                raise ArgumentError.new "#{k} is not a scope that returns an ActiveRecord::Relation" unless ransack_scope.is_a? ::ActiveRecord::Relation
              else
                ransack_params.merge!(k => v)
              end
            end
          end

          ransack_scope.search_without_scopes(ransack_params, options)
        end

        alias_method_chain :search, :scopes
        
        # refresh already existing ransack alias
        alias_method :ransack, :search
      end
    end
  end
end

it doesn't work in this way:

Debt.search({'combinator' => 'or', 'groupings' => { '0' => {'overdue' => true}, '1' => {'amount_gteq' => 10}}}).result.to_sql

result is:

SELECT "debts".* FROM "debts"  WHERE "debts"."amount" >= 10

but should be:

SELECT "debts".* FROM "debts"  WHERE (`debts`.`status` = 'open' AND (due_date < '2012-11-23')) OR (`debts`.`amount` >= 10.0)

What are you think about this?