portfolio_item.rb

class PortfolioItem
  include Mongoid::Document
  include Mongoid::Slug
  include ComparableByIndex
  include CanBePublished

  embedded_in :portfolio, inverse_of: :portfolio_items
  field :title
  slug :title, history: true, scope: :portfolio
  field :client, type: String
  field :description
  field :date, type: Date
  embeds_many :images, cascade_callbacks: true
  validates_presence_of :title
  
  def ext_title
    client.nil? ? title : "#{title} - #{client}"
  end

  def get_image_index(image)
    if image.nil?
      return -1
    end
    idx = images.sorted.published.entries.index { |x| x.id == image.id }
    return idx || -1
  end

  def next_image(image)
    index = get_image_index(image)
    (index + 1) == images.published.count ? nil : images.sorted.published.entries[index + 1]
  end

  def previous_image(image)
    index = get_image_index(image)
    index == 0 ? nil : images.published.sorted.entries[index - 1]
  end

end