1 files changed, 55 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/validations/acceptance.rb b/activemodel/lib/active_model/validations/acceptance.rb
new file mode 100644
index 0000000000..ac5e79859b
--- /dev/null
+++ b/activemodel/lib/active_model/validations/acceptance.rb
@@ -0,0 +1,55 @@
+module ActiveModel
+
+  module Validations
+    class AcceptanceValidator < EachValidator # :nodoc:
+      def initialize(options)
+        super({ allow_nil: true, accept: "1" }.merge!(options))
+        setup!(options[:class])
+      end
+
+      def validate_each(record, attribute, value)
+        unless value == options[:accept]
+          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)
+      end
+    end
+
+    module HelperMethods
+      # Encapsulates the pattern of wanting to validate the acceptance of a
+      # terms of service check box (or similar agreement).
+      #
+      #   class Person < ActiveRecord::Base
+      #     validates_acceptance_of :terms_of_service
+      #     validates_acceptance_of :eula, message: 'must be abided'
+      #   end
+      #
+      # If the database column does not exist, the +terms_of_service+ attribute
+      # is entirely virtual. This check is performed only if +terms_of_service+
+      # is not +nil+ and by default on save.
+      #
+      # 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
+      #   a database column, since the attribute is typecast from "1" to +true+
+      #   before validation.
+      #
+      # There is also a list of default options supported by every validator:
+      # +:if+, +:unless+, +:on+, +:allow_nil+, +:allow_blank+, and +:strict+.
+      # See <tt>ActiveModel::Validation#validates</tt> for more information.
+      def validates_acceptance_of(*attr_names)
+        validates_with AcceptanceValidator, _merge_attributes(attr_names)
+      end
+    end
+  end
+end