Move writing unknown column exception to null attribute

Making this change revealed several subtle bugs related to models with
no primary key, and anonymous classes. These have been fixed as well,
with regression tests added.

2 files changed, 2 insertions, 9 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index 1c81a5b71b..cadad60ddd 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -83,12 +83,9 @@ module ActiveRecord
         end
 
         def get_primary_key(base_name) #:nodoc:
-          return 'id' if base_name.blank?
-
-          case primary_key_prefix_type
-          when :table_name
+          if base_name && primary_key_prefix_type == :table_name
             base_name.foreign_key(false)
-          when :table_name_with_underscore
+          elsif base_name && primary_key_prefix_type == :table_name_with_underscore
             base_name.foreign_key
           else
             if ActiveRecord::Base != self && table_exists?
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index 94fce2db60..b3c8209a74 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -70,10 +70,6 @@ module ActiveRecord
         attr_name = attr_name.to_s
         attr_name = self.class.primary_key if attr_name == 'id' && self.class.primary_key
 
-        unless has_attribute?(attr_name) || self.class.columns_hash.key?(attr_name)
-          raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{attr_name}'"
-        end
-
         if should_type_cast
           @attributes.write_from_user(attr_name, value)
         else