Fix regression from [1631] that caused an attribute to be set to nil if it was assigned false

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1709 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/base.rb

@@ -1200,7 +1200,7 @@ module ActiveRecord #:nodoc:
       # Returns the value of attribute identified by <tt>attr_name</tt> after it has been type cast (for example,
       # "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
       def read_attribute(attr_name)
-        if value = @attributes[attr_name]
+        if !(value = @attributes[attr_name]).nil?
           if column = column_for_attribute(attr_name)
             if unserializable_attribute?(attr_name, column)
               unserialize_attribute(attr_name)

activerecord/test/base_test.rb

@@ -180,6 +180,12 @@ class BasicsTest < Test::Unit::TestCase
     assert_equal "Still another topic: part 2", topic.title
   end
 
+  def test_read_attribute_when_false
+    topic = topics(:first)
+    topic.approved = false
+    assert_equal 0, topic.approved, "approved should be 0"
+  end
+
   def test_preserving_date_objects
     # SQL Server doesn't have a separate column type just for dates, so all are returned as time
     if ActiveRecord::ConnectionAdapters.const_defined? :SQLServerAdapter