allow proc for brands option

lib/active_model/credit_card_number_validator.rb

@@ -15,15 +15,35 @@
 #     attr_accessor :number
 #     include ActiveModel::Validations
 #     validates :number, credit_card_number: {except: [:maestro]}
-#   end
+#  end
+#
+#  Proc can be used as well
+#
+#  class CreditCard
+#     attr_accessor :number, :card_type
+#     include ActiveModel::Validations
+#     validates :number, credit_card_number: {brands: ->{|record|  Array(record.accepted_brands) }  }
+#
+#     def accepted_brands
+#       if card_type == 'Maestro'
+#         :maestro
+#       elsif card_type == 'American Express'
+#         :amex
+#       else
+#         :visa
+#       end
+#     end
+#
+#  end
+#
 #
 
 module ActiveModel
   module Validations
     class CreditCardNumberValidator < EachValidator
 
       def validate_each(record, attribute, value)
-        record.errors.add(attribute) unless credit_card_valid?(value, extract_brands(options))
+        record.errors.add(attribute) unless credit_card_valid?(value, extract_brands(record, options))
       end
 
       def credit_card_valid?(number, brands = [])
@@ -32,17 +52,27 @@ def credit_card_valid?(number, brands = [])
 
       protected
 
-      def extract_brands(options)
-         if options.has_key?(:brands)
-           options[:brands] == :any ? [] : Array(options[:brands])
-         elsif options.has_key?(:only)
-           Array(options[:only])
-         elsif options.has_key?(:except)
-           Array(CreditCardValidations::Detector.brands.keys) - Array(options[:except])
-         else
-           []
-         end
+      def extract_brands(record, options)
+        if options.has_key?(:brands)
+          with_brands(record, options[:brands])
+        elsif options.has_key?(:only)
+          Array(options[:only])
+        elsif options.has_key?(:except)
+          Array(CreditCardValidations::Detector.brands.keys) - Array(options[:except])
+        else
+          []
+        end
+
+      end
 
+      def with_brands(record, brands)
+        if brands.is_a?(Proc)
+          brands.call(record)
+        elsif options[:brands] == :any
+          []
+        else
+          Array(options[:brands])
+        end
       end
 
     end

spec/active_model_spec.rb

@@ -4,14 +4,30 @@
 
   let(:model) { CreditCard.new }
 
+  describe "Proc support" do
+    it "should be valid if brands from proc valid" do
+       card = model.dup
+       card.card_type =  "Master Card"
+       card.number6 =  CreditCardValidations::Factory.random(:visa)
+       card.valid?.must_equal false
+       card.number6 =  CreditCardValidations::Factory.random(:mastercard)
+       card.valid?.must_equal true
+
+    end
+
+  end
+
   describe "Any Brand" do
-    it "should be alid for all prepared valid numbers" do
+    it "should be valid for all prepared valid numbers" do
       VALID_NUMBERS.each do |_, numbers|
 
         numbers.each do |number|
           card = model
           card.number4 = number
           card.number5 = number
+          unless card.valid?
+            p card.errors
+          end
           card.valid?.must_equal true
 
         end

spec/models/credit_card.rb

@@ -1,9 +1,19 @@
 class CreditCard
-  attr_accessor :number, :number2, :number3, :number4, :number5
+  attr_accessor :number, :number2, :number3, :number4, :number5, :number6, :card_type
   include ActiveModel::Validations
   validates :number, credit_card_number: {brands: [:amex, :maestro]} , allow_blank: true
   validates :number2, credit_card_number: {only: [:amex, :maestro]},  allow_blank: true
   validates :number3, credit_card_number: {except: [:amex, :maestro]} , allow_blank: true
   validates :number4, credit_card_number: {brands: :any}  , allow_blank: true
   validates :number5, credit_card_number: true , allow_blank: true
+  validates :number6, credit_card_number: { brands: ->(record){ record.supported_brand } } , allow_blank: true
+
+
+  def supported_brand
+    {
+      "Master Card" => :mastercard,
+      "Visa" => :visa
+    }[self.card_type]
+  end
+
 end