1 files changed, 61 insertions, 9 deletions

diff --git a/activemodel/lib/active_model/validations/acceptance.rb b/activemodel/lib/active_model/validations/acceptance.rb
index ac5e79859b..c5c0cd4636 100644
--- a/activemodel/lib/active_model/validations/acceptance.rb
+++ b/activemodel/lib/active_model/validations/acceptance.rb
@@ -3,22 +3,73 @@ module ActiveModel
   module Validations
     class AcceptanceValidator < EachValidator # :nodoc:
       def initialize(options)
-        super({ allow_nil: true, accept: "1" }.merge!(options))
+        super({ allow_nil: true, accept: ["1", true] }.merge!(options))
         setup!(options[:class])
       end
 
       def validate_each(record, attribute, value)
-        unless value == options[:accept]
+        unless acceptable_option?(value)
           record.errors.add(attribute, :accepted, options.except(:accept, :allow_nil))
         end
       end
 
       private
+
       def setup!(klass)
-        attr_readers = attributes.reject { |name| klass.attribute_method?(name) }
-        attr_writers = attributes.reject { |name| klass.attribute_method?("#{name}=") }
-        klass.send(:attr_reader, *attr_readers)
-        klass.send(:attr_writer, *attr_writers)
+        klass.include(LazilyDefineAttributes.new(AttributeDefinition.new(attributes)))
+      end
+
+      def acceptable_option?(value)
+        Array(options[:accept]).include?(value)
+      end
+
+      class LazilyDefineAttributes < Module
+        def initialize(attribute_definition)
+          define_method(:respond_to_missing?) do |method_name, include_private=false|
+            super(method_name, include_private) || attribute_definition.matches?(method_name)
+          end
+
+          define_method(:method_missing) do |method_name, *args, &block|
+            if attribute_definition.matches?(method_name)
+              attribute_definition.define_on(self.class)
+              send(method_name, *args, &block)
+            else
+              super(method_name, *args, &block)
+            end
+          end
+        end
+      end
+
+      class AttributeDefinition
+        def initialize(attributes)
+          @attributes = attributes.map(&:to_s)
+        end
+
+        def matches?(method_name)
+          attr_name = convert_to_reader_name(method_name)
+          attributes.include?(attr_name)
+        end
+
+        def define_on(klass)
+          attr_readers = attributes.reject { |name| klass.attribute_method?(name) }
+          attr_writers = attributes.reject { |name| klass.attribute_method?("#{name}=") }
+          klass.send(:attr_reader, *attr_readers)
+          klass.send(:attr_writer, *attr_writers)
+        end
+
+        protected
+
+        attr_reader :attributes
+
+        private
+
+        def convert_to_reader_name(method_name)
+          attr_name = method_name.to_s
+          if attr_name.end_with?("=")
+            attr_name = attr_name[0..-2]
+          end
+          attr_name
+        end
       end
     end
 
@@ -38,9 +89,10 @@ module ActiveModel
       # Configuration options:
       # * <tt>:message</tt> - A custom error message (default is: "must be
       #   accepted").
-      # * <tt>:accept</tt> - Specifies value that is considered accepted.
-      #   The default value is a string "1", which makes it easy to relate to
-      #   an HTML checkbox. This should be set to +true+ if you are validating
+      # * <tt>:accept</tt> - Specifies a value that is considered accepted.
+      #   Also accepts an array of possible values. The default value is
+      #   an array ["1", true], which makes it easy to relate to an HTML
+      #   checkbox. This should be set to, or include, +true+ if you are validating
       #   a database column, since the attribute is typecast from "1" to +true+
       #   before validation.
       #