Mysql2::Error: All parts of a PRIMARY KEY must be NOT NULL; if you need NULL in a key, use UNIQUE instead

Question

I have created a demo application in rails 3.2.9 and ruby versiion 2.0.0 . After scaffolding Blog model I am trying to migrate it, but having following

Answer 1

config/initializers/abstract_mysql2_adapter.rb

require 'active_record/connection_adapters/mysql2_adapter'

class ActiveRecord::ConnectionAdapters::Mysql2Adapter
  NATIVE_DATABASE_TYPES[:primary_key] = "int(11) auto_increment PRIMARY KEY"
end