1 files changed, 19 insertions, 4 deletions
diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index aa92343f76..609c6e8cab 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -56,7 +56,7 @@ module ActiveRecord
       #   # => false
       def instance_method_already_implemented?(method_name)
         if dangerous_attribute_method?(method_name)
-          raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord"
+          raise DangerousAttributeError, "#{method_name} is defined by Active Record"
         end
 
         if superclass == Base
@@ -163,8 +163,22 @@ module ActiveRecord
     #   person.respond_to('age?')   # => true
     #   person.respond_to(:nothing) # => false
     def respond_to?(name, include_private = false)
+      name = name.to_s
       self.class.define_attribute_methods unless self.class.attribute_methods_generated?
-      super
+      result = super
+
+      # If the result is false the answer is false.
+      return false unless result
+
+      # If the result is true then check for the select case.
+      # For queries selecting a subset of columns, return false for unselected columns.
+      # We check defined?(@attributes) not to issue warnings if called on objects that
+      # have been allocated but not yet initialized.
+      if defined?(@attributes) && @attributes.present? && self.class.column_names.include?(name)
+        return has_attribute?(name)
+      end
+
+      return true
     end
 
     # Returns +true+ if the given attribute is in the attributes hash, otherwise +false+.
@@ -328,13 +342,14 @@ module ActiveRecord
     end
 
     def attribute_method?(attr_name) # :nodoc:
+      # We check defined? because Syck calls respond_to? before actually calling initialize.
       defined?(@attributes) && @attributes.include?(attr_name)
     end
 
     private
 
     # Returns a Hash of the Arel::Attributes and attribute values that have been
-    # type casted for use in an Arel insert/update method.
+    # typecasted for use in an Arel insert/update method.
     def arel_attributes_with_values(attribute_names)
       attrs = {}
       arel_table = self.class.arel_table
@@ -348,7 +363,7 @@ 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) && !pk_attribute?(name) && !readonly_attribute?(name)
+        column_for_attribute(name) && !readonly_attribute?(name)
       end
     end