Are there any 'protected' names you should

Question

This question already has an answer here:

• Reserved names with ActiveRecord models 4 answers

I'm new to Rails and I just wondered if there were any protected names you should avoid using in your models? For example, would the following be valid:

class CreateModel < ActiveRecord::Migration
  def change
    create_table :model do |t|
      t.string :hash
      t.integer :count

      t.timestamps
    end
  end
end

I realise has probably isn't a great name for a property, but it's a pure example.

Edit: All the responses were good, but I've chosen my accepted answer because it contains a link to a huge list of protected attributes.

Answer 1

I can remember only two:

1. type, because Rails treats this property as a type of parent object in polymorphic objects.
2. order and any other SQL commands/statements/etc., because Rails generating SQL queries is using them and usually an exception occurs.

Answer 2

Avoid class names, if they are defined:

!!defined? Class  # => true
!!defined? Model  # => false

Avoid column names within this list:

• id - Reserved for primary keys
• lock_version
• type - single table inheritance and must contain a class name
• table_name_count - Reserved for counter cache
• position - Reserved for acts_as_list
• parent_id - Reserved for acts_as_tree
• lft - Reserved for acts_as_nested_set
• rgt - Reserved for acts_as_nested_set
• quote - Method in ActiveRecord::Base which is used to quote SQL
• template

Answer 3

I personally ran into an issue where I named my model record:

• https://github.com/rails/rails/issues/11645
• ActiveRecord belongs_to association does not save foreign_key (Rails 4)

Other than that:

• http://reservedwords.herokuapp.com/
• Reserved names with ActiveRecord models

Answer 4

I had an issues with an external db and a column named "hash". The offending column can be ignored in this manner:

class SomeClass < ActiveRecord::Base
  class << self # Class methods
    alias :all_columns :columns 

    def columns 
      all_columns.reject {|c| c.name == 'hash'} 
    end 
  end 
end