bigdir/app/models/user_extensions.rb

class UserExtensions < ActiveRecord::Base
  belongs_to :user
  attr_accessible :user_id,:birthday,:brief_introduction,:gender,:location,:occupation,:work_experience,:zip_code,:identity, :technical_title,:student_id
  #this method was used to update the table user_extensions
  def update_user_extensions(birthday=nil,brief_introduction=nil,
                              gender=nil,location=nil,occupation=nil,work_experience=nil,zip_code=nil)
     self.birthday = birthday
     self.brief_introduction = brief_introduction
     self.gender = gender
     self.location = location
     self.occupation = occupation
     self.work_experience = work_experience
     self.zip_code = zip_code
     self.save
  end
  
  def get_brief_introduction
     return self.brief_introduction
  end
  
  def self.introduction(user, message)
    unless user.user_extensions.nil?
       info = user.user_extensions
       info.brief_introduction = message
       info.save
    else
       info = UserExtensions.new
       info.user_id = user.id
       info.brief_introduction = message
       info.save
    end
  end
end