1 files changed, 19 insertions, 7 deletions

diff --git a/activemodel/lib/active_model/validations/length.rb b/activemodel/lib/active_model/validations/length.rb
index e4a1f9e80a..ddfd8a342e 100644
--- a/activemodel/lib/active_model/validations/length.rb
+++ b/activemodel/lib/active_model/validations/length.rb
@@ -1,10 +1,10 @@
 module ActiveModel
 
-  # == Active Model Length Validator
+  # == Active \Model Length \Validator
   module Validations
-    class LengthValidator < EachValidator #:nodoc:
-      MESSAGES  = { :is => :wrong_length, :minimum => :too_short, :maximum => :too_long }.freeze
-      CHECKS    = { :is => :==, :minimum => :>=, :maximum => :<= }.freeze
+    class LengthValidator < EachValidator # :nodoc:
+      MESSAGES  = { is: :wrong_length, minimum: :too_short, maximum: :too_long }.freeze
+      CHECKS    = { is: :==, minimum: :>=, maximum: :<= }.freeze
 
       RESERVED_OPTIONS  = [:minimum, :maximum, :within, :is, :tokenizer, :too_short, :too_long]
 
@@ -14,6 +14,10 @@ module ActiveModel
           options[:minimum], options[:maximum] = range.min, range.max
         end
 
+        if options[:allow_blank] == false && options[:minimum].nil? && options[:is].nil?
+          options[:minimum] = 1
+        end
+
         super
       end
 
@@ -37,10 +41,13 @@ module ActiveModel
         value = tokenize(value)
         value_length = value.respond_to?(:length) ? value.length : value.to_s.length
         errors_options = options.except(*RESERVED_OPTIONS)
-        
+
         CHECKS.each do |key, validity_check|
           next unless check_value = options[key]
-          next if value_length.send(validity_check, check_value)
+
+          if !value.nil? || skip_nil_check?(key)
+            next if value_length.send(validity_check, check_value)
+          end
 
           errors_options[:count] = check_value
 
@@ -58,6 +65,10 @@ module ActiveModel
           options[:tokenizer].call(value)
         end || value
       end
+
+      def skip_nil_check?(key)
+        key == :maximum && options[:allow_nil].nil? && options[:allow_blank].nil?
+      end
     end
 
     module HelperMethods
@@ -79,7 +90,8 @@ module ActiveModel
       #
       # Configuration options:
       # * <tt>:minimum</tt> - The minimum size of the attribute.
-      # * <tt>:maximum</tt> - The maximum size of the attribute.
+      # * <tt>:maximum</tt> - The maximum size of the attribute. Allows +nil+ by
+      #   default if not used with :minimum.
       # * <tt>:is</tt> - The exact size of the attribute.
       # * <tt>:within</tt> - A range specifying the minimum and maximum size of
       #   the attribute.