Merge branch 'master' of github.com:rails/rails

* 'master' of github.com:rails/rails:
  For our build, stick with mail 2.5.x for now
  Correct result, previously showing wrong result
  Collapse PG default extractoin of most types to single regex
  Change wording of explanation about precision & scale of decimal numbers [ci skip]
  Cleaned up duplicated CHANGELOG entry [ci skip]
  reuse available belongs_to? method
  Convert StrongParameters cache to a hash. This fixes an unbounded memory leak demonstrated on @tenderlove's latest blog post:
  Partially revert deprecation of *_filter
  Pluralize params
  Add default_i18n_subject to the guides
  Fix regression on eager loading association based on SQL query rather than existing column.
  Relax mail gem constraint from ~> 2.5.4 to ~> 2.5, >= 2.5.4
  Keep column defaults in type cast form
  Return a null column when no column exists for an attribute
  Refactor XML serializer to not depend on `serialized_attributes`
  Test the serialized types of virtual columns in XML
  implement ActiveRecord::Base#pretty_print + changelog
  Remove duplicated HashWithIndifferentAccess#with_indifferent_access.

2 files changed, 8 insertions, 7 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
index 6cd4e43ddd..4e32b78e34 100644
--- a/activerecord/lib/active_record/attribute_methods/dirty.rb
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -94,8 +94,7 @@ module ActiveRecord
       end
 
       def _field_changed?(attr, old, value)
-        column = column_for_attribute(attr) || Type::Value.new
-        column.changed?(old, value)
+        column_for_attribute(attr).changed?(old, value)
       end
     end
   end
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index c3e601a208..5203b30462 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -72,18 +72,20 @@ module ActiveRecord
         @attributes.delete(attr_name)
         column = column_for_attribute(attr_name)
 
+        unless has_attribute?(attr_name) || self.class.columns_hash.key?(attr_name)
+          raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{attr_name}'"
+        end
+
         # If we're dealing with a binary column, write the data to the cache
         # so we don't attempt to typecast multiple times.
-        if column && column.binary?
+        if column.binary?
           @attributes[attr_name] = value
         end
 
-        if column && should_type_cast
+        if should_type_cast
           @raw_attributes[attr_name] = column.type_cast_for_write(value)
-        elsif !should_type_cast || @raw_attributes.has_key?(attr_name)
-          @raw_attributes[attr_name] = value
         else
-          raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{attr_name}'"
+          @raw_attributes[attr_name] = value
         end
       end
     end