parameters.rb

require 'date'
require 'bigdecimal'
require 'stringio'

require 'active_support/concern'
require 'active_support/core_ext/hash/indifferent_access'
require 'active_support/core_ext/array/wrap'
require 'action_controller'
require 'action_dispatch/http/upload'

module ActionController
  class ParameterMissing < IndexError
    attr_reader :param

    def initialize(param)
      @param = param
      super("param is missing or the value is empty: #{param}")
    end
  end

  class UnpermittedParameters < IndexError
    attr_reader :params

    def initialize(params)
      @params = params
      super("found unpermitted parameters: #{params.join(", ")}")
    end
  end

  class Parameters < ActiveSupport::HashWithIndifferentAccess
    attr_accessor :permitted
    alias :permitted? :permitted
    
    cattr_accessor :action_on_unpermitted_parameters, :instance_accessor => false

    # Never raise an UnpermittedParameters exception because of these params
    # are present. They are added by Rails and it's of no concern.
    NEVER_UNPERMITTED_PARAMS = %w( controller action )

    def initialize(attributes = nil)
      super(attributes)
      @permitted = false
    end

    def permit!
      each_pair do |key, value|
        value = convert_hashes_to_parameters(key, value)
        Array.wrap(value).each do |_|
          _.permit! if _.respond_to? :permit!
        end
      end

      @permitted = true
      self
    end

    def require(key)
      self[key].presence || raise(ActionController::ParameterMissing.new(key))
    end

    alias :required :require

    def permit(*filters)
      params = self.class.new

      filters.each do |filter|
        case filter
        when Symbol, String
          permitted_scalar_filter(params, filter)
        when Hash then
          hash_filter(params, filter)
        end
      end

      unpermitted_parameters!(params) if self.class.action_on_unpermitted_parameters

      params.permit!
    end

    def [](key)
      convert_hashes_to_parameters(key, super)
    end

    def fetch(key, *args)
      convert_hashes_to_parameters(key, super, false)
    rescue KeyError, IndexError
      raise ActionController::ParameterMissing.new(key)
    end

    def slice(*keys)
      self.class.new(super).tap do |new_instance|
        new_instance.instance_variable_set :@permitted, @permitted
      end
    end

    def dup
      self.class.new(self).tap do |duplicate|
        duplicate.default = default
        duplicate.instance_variable_set :@permitted, @permitted
      end
    end

    protected
      def convert_value(value)
        if value.class == Hash
          self.class.new_from_hash_copying_default(value)
        elsif value.is_a?(Array)
          value.dup.replace(value.map { |e| convert_value(e) })
        else
          value
        end
      end

    private

      def convert_hashes_to_parameters(key, value, assign_if_converted=true)
        converted = convert_value_to_parameters(value)
        self[key] = converted if assign_if_converted && !converted.equal?(value)
        converted
      end

      def convert_value_to_parameters(value)
        if value.is_a?(Array)
          value.map { |_| convert_value_to_parameters(_) }
        elsif value.is_a?(Parameters) || !value.is_a?(Hash)
          value
        else
          self.class.new(value)
        end
      end

      #
      # --- Filtering ----------------------------------------------------------
      #

      # This is a white list of permitted scalar types that includes the ones
      # supported in XML and JSON requests.
      #
      # This list is in particular used to filter ordinary requests, String goes
      # as first element to quickly short-circuit the common case.
      #
      # If you modify this collection please update the README.
      PERMITTED_SCALAR_TYPES = [
        String,
        Symbol,
        NilClass,
        Numeric,
        TrueClass,
        FalseClass,
        Date,
        Time,
        # DateTimes are Dates, we document the type but avoid the redundant check.
        StringIO,
        IO,
        ActionDispatch::Http::UploadedFile,
        Rack::Test::UploadedFile,
      ]

      def permitted_scalar?(value)
        PERMITTED_SCALAR_TYPES.any? {|type| value.is_a?(type)}
      end

      def array_of_permitted_scalars?(value)
        if value.is_a?(Array)
          value.all? {|element| permitted_scalar?(element)}
        end
      end

      def permitted_scalar_filter(params, key)
        if has_key?(key) && permitted_scalar?(self[key])
          params[key] = self[key]
        end

        keys.grep(/\A#{Regexp.escape(key.to_s)}\(\d+[if]?\)\z/).each do |key|
          if permitted_scalar?(self[key])
            params[key] = self[key]
          end
        end
      end

      def array_of_permitted_scalars_filter(params, key, hash = self)
        if hash.has_key?(key) && array_of_permitted_scalars?(hash[key])
          params[key] = hash[key]
        end
      end

      def hash_filter(params, filter)
        filter = filter.with_indifferent_access

        # Slicing filters out non-declared keys.
        slice(*filter.keys).each do |key, value|
          next unless value

          if filter[key] == []
            # Declaration {:comment_ids => []}.
            array_of_permitted_scalars_filter(params, key)
          else
            # Declaration {:user => :name} or {:user => [:name, :age, {:adress => ...}]}.
            params[key] = each_element(value) do |element, index|
              if element.is_a?(Hash)
                element = self.class.new(element) unless element.respond_to?(:permit)
                element.permit(*Array.wrap(filter[key]))
              elsif filter[key].is_a?(Hash) && filter[key][index] == []
                array_of_permitted_scalars_filter(params, index, value)
              end
            end
          end
        end
      end

      def each_element(value)
        if value.is_a?(Array)
          value.map { |el| yield el }.compact
          # fields_for on an array of records uses numeric hash keys.
        elsif fields_for_style?(value)
          hash = value.class.new
          value.each { |k,v| hash[k] = yield(v, k) }
          hash
        else
          yield value
        end
      end

      def fields_for_style?(object)
        object.is_a?(Hash) && object.all? { |k, v| k =~ /\A-?\d+\z/ && v.is_a?(Hash) }
      end

      def unpermitted_parameters!(params)  
        return unless self.class.action_on_unpermitted_parameters
        
        unpermitted_keys = unpermitted_keys(params)

        if unpermitted_keys.any?  
          case self.class.action_on_unpermitted_parameters  
          when :log
            name = "unpermitted_parameters.action_controller"
            ActiveSupport::Notifications.instrument(name, :keys => unpermitted_keys)
          when :raise  
            raise ActionController::UnpermittedParameters.new(unpermitted_keys)  
          end  
        end  
      end  
  
      def unpermitted_keys(params)  
        self.keys - params.keys - NEVER_UNPERMITTED_PARAMS
      end
  end

  module StrongParameters
    extend ActiveSupport::Concern

    included do
      rescue_from(ActionController::ParameterMissing) do |parameter_missing_exception|
        render :text => "Required parameter missing: #{parameter_missing_exception.param}", :status => :bad_request
      end
    end

    def params
      @_params ||= Parameters.new(request.parameters)
    end

    def params=(val)
      @_params = val.is_a?(Hash) ? Parameters.new(val) : val
    end
  end
end