photo.rb

class Photo < ActiveRecord::Base
  belongs_to :post, :class_name => "Forem::Post"

  has_attached_file :attachment,
    path: ":rails_root/public/system/attachments/:id/:style/:filename",
    url: "/system/attachments/:id/:style/:filename",
    styles: {
      display: "450x450>",
      thumbnail: "70x70#"
    },
    convert_options: { all: "-quality 100" },
    processors: [:thumbnail, :compression]

  validates_attachment_presence :attachment
  validates_attachment :attachment, content_type: {
    content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"]
  }
end