add example to ActiveModel::MissingAttributeError [ci skip]

1 files changed, 8 insertions, 0 deletions

diff --git a/activemodel/lib/active_model/attribute_methods.rb b/activemodel/lib/active_model/attribute_methods.rb
index eb06250060..b1bef4b1e1 100644
--- a/activemodel/lib/active_model/attribute_methods.rb
+++ b/activemodel/lib/active_model/attribute_methods.rb
@@ -3,6 +3,14 @@ require 'active_support/deprecation'
 
 module ActiveModel
   # Raised when an attribute is not defined.
+  #
+  #   class User < ActiveRecord::Base
+  #     has_many :pets
+  #   end
+  #
+  #   user = User.first
+  #   user.pets.select(:id).first.user_id
+  #   # => ActiveModel::MissingAttributeError: missing attribute: user_id
   class MissingAttributeError < NoMethodError
   end
   # == Active Model Attribute Methods