1 files changed, 26 insertions, 26 deletions

diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index fb6473b7c7..e626227e7e 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -18,6 +18,8 @@ module ActiveRecord
       include TimeZoneConversion
       include Dirty
       include Serialization
+
+      delegate :column_for_attribute, to: :class
     end
 
     AttrNames = Module.new {
@@ -192,6 +194,26 @@ module ActiveRecord
             []
           end
       end
+
+      # Returns the column object for the named attribute.
+      # Returns a +ActiveRecord::ConnectionAdapters::NullColumn+ if the
+      # named attribute does not exist.
+      #
+      #   class Person < ActiveRecord::Base
+      #   end
+      #
+      #   person = Person.new
+      #   person.column_for_attribute(:name) # the result depends on the ConnectionAdapter
+      #   # => #<ActiveRecord::ConnectionAdapters::SQLite3Column:0x007ff4ab083980 @name="name", @sql_type="varchar(255)", @null=true, ...>
+      #
+      #   person.column_for_attribute(:nothing)
+      #   # => #<ActiveRecord::ConnectionAdapters::NullColumn:0xXXX @name=nil, @sql_type=nil, @cast_type=#<Type::Value>, ...>
+      def column_for_attribute(name)
+        name = name.to_s
+        columns_hash.fetch(name) do
+          ConnectionAdapters::NullColumn.new(name)
+        end
+      end
     end
 
     # If we haven't generated any methods yet, generate them, then
@@ -287,11 +309,6 @@ module ActiveRecord
       }
     end
 
-    # Placeholder so it can be overriden when needed by serialization
-    def attributes_for_coder # :nodoc:
-      attributes
-    end
-
     # Returns an <tt>#inspect</tt>-like string for the value of the
     # attribute +attr_name+. String attributes are truncated upto 50
     # characters, Date and Time attributes are returned in the
@@ -344,23 +361,6 @@ module ActiveRecord
       !value.nil? && !(value.respond_to?(:empty?) && value.empty?)
     end
 
-    # Returns the column object for the named attribute. Returns +nil+ if the
-    # named attribute not exists.
-    #
-    #   class Person < ActiveRecord::Base
-    #   end
-    #
-    #   person = Person.new
-    #   person.column_for_attribute(:name) # the result depends on the ConnectionAdapter
-    #   # => #<ActiveRecord::ConnectionAdapters::SQLite3Column:0x007ff4ab083980 @name="name", @sql_type="varchar(255)", @null=true, ...>
-    #
-    #   person.column_for_attribute(:nothing)
-    #   # => nil
-    def column_for_attribute(name)
-      # FIXME: should this return a null object for columns that don't exist?
-      self.class.columns_hash[name.to_s]
-    end
-
     # Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
     # "2004-12-12" in a date column is cast to a date object, like Date.new(2004, 12, 12)). It raises
     # <tt>ActiveModel::MissingAttributeError</tt> if the identified attribute is missing.
@@ -443,16 +443,16 @@ module ActiveRecord
 
     # Filters the primary keys and readonly attributes from the attribute names.
     def attributes_for_update(attribute_names)
-      attribute_names.select do |name|
-        column_for_attribute(name) && !readonly_attribute?(name)
+      attribute_names.reject do |name|
+        readonly_attribute?(name)
       end
     end
 
     # Filters out the primary keys, from the attribute names, when the primary
     # key is to be generated (e.g. the id attribute has no value).
     def attributes_for_create(attribute_names)
-      attribute_names.select do |name|
-        column_for_attribute(name) && !(pk_attribute?(name) && id.nil?)
+      attribute_names.reject do |name|
+        pk_attribute?(name) && id.nil?
       end
     end