You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: user.rb
    path of file: ./repos/airbnb-clone/app/models
    
    the code of the file until where you have to start completion: class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable,
         :omniauthable
  validates :full
    
  def self.from_omniauth(auth)
    user = User.where(email: auth.info.email).first
    if user
      return user
    else
      where(provider: auth.provider, uid: auth.uid).first_or_create do |user|
        user.fullname = auth.info.name
        user.provider = auth.provider
        user.uid = auth.uid
        user.email = auth.info.email
        user.image = auth.info.image
        user.password = Devise.friendly_token[0, 20]
      end
    end