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: open_graph_cache.rb
    path of file: ./repos/diaspora/app/models
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

class OpenGraphCache < ApplicationRecord
  validates :title, :presence => true
  validates :ob_type, :presence => true
  validates :image, :presence => true
  validates :url, :presence => true

  has_many :posts

  acts_as_api
  api_accessible
    
  def fetch_and_save_opengraph_data!
    uri = URI.parse(url.start_with?("http") ? url : "http://#{url}")
    uri.normalize!
    object = OpenGraphReader.fetch!(uri)

    return unless object

    self.title = object.og.title.truncate(255)
    self.ob_type = object.og.type
    self.image = object.og.image.url
    self.url = object.og.url
    self.description = object.og.description
    if object.og.video.try(:secure_url) && secure_video_url?(object.og.video.secure_url)
      self.video_url = object.og.video.secure_url
    end