Migrate from Ghost JSON into Jekyll Markdown Files

migrate_ghost_to_jekyll.rb

#!/usr/bin/env ruby

require 'fileutils'
require 'json'
require 'date'
require 'yaml'

FileUtils.mkdir_p("_posts")
FileUtils.mkdir_p("_drafts")
FileUtils.mkdir_p("_data")

$json = JSON.parse File.read(ARGV.pop), symbolize_names: true

unless $json[:data].nil?
  posts = $json[:data][:posts]
else
  posts = $json[:db].first[:data][:posts]
end

def there_are_tags?
  @tags ||=
    $json[:db] &&
    $json[:db].first[:data][:posts_tags] &&
    $json[:db].first[:data][:tags]
end

@imported = Hash.new(0)

class Post
  # the source of the post
  attr_reader :post

  def initialize post
    @post = post
  end

  def import
    puts "Importing #{ filename }"
    File.write filename, full_body
  end

  def draft?
    post[:status] == 'draft'
  end

  private

  def folder
    draft? ? '_drafts' : '_posts'
  end

  def filename
    File.join folder, basename
  end

  def date
    case post[:published_at]
    when String
      DateTime.parse(post[:published_at])
    when Integer
      Time.at(post[:published_at] / 1000).utc.to_datetime
    end
  end

  def front_matter
    front_matter_hash = {
      'layout'            => 'single',
      'title'             => post[:title],
      'header'            => {
        'image'   => post[:image],
        'caption' => "Photo credit: [**Unsplash**](https://unsplash.com)"
      },
      'meta_title'        => post[:meta_title],
      'meta_description'  => post[:meta_description]
    }
    unless draft?
      front_matter_hash['date'] = date.strftime('%Y-%m-%d %H:%M:%S') if date
    end
    front_matter_hash['tags'] = tags if tags && !tags.empty?
    front_matter_hash
  end

  def slug
    post[:slug]
  end

  def tags
    if there_are_tags?
      post_tags = $json[:db].first[:data][:posts_tags].select do |pt|
        pt[:post_id] == post[:id]
      end
      tags_ids = post_tags.map { |pt| pt[:tag_id] }
      tags = $json[:db].first[:data][:tags].select do |t|
        tags_ids.include? t[:id]
      end
      tags.map { |t| t[:slug] }
    end
  end

  def full_body
    front_matter.to_yaml + "---\n\n" + post[:markdown]
  end

  def basename
    if draft?
      "#{ slug }.markdown"
    else
      "#{ date.strftime('%Y-%m-%d') }-#{ slug }.markdown"
    end
  end
end

posts.each do |post|
  post = Post.new post
  post.import
  @imported[:posts] += 1
  @imported[:drafts] += 1 if post.draft?
end

tags = $json[:db].first[:data][:tags].map do |tg|
  {
    'name': tg[:name],
    'slug': tg[:slug],
    'description': tg[:description],
    'meta_title': tg[:meta_title],
    'meta_description': tg[:meta_description],
    'image': tg[:image]
  }
end

puts "Importing tags"
File.write "_data/tags.yml", tags.to_yaml

puts "#{ @imported[:posts] } posts imported ( #{ @imported[:drafts] } draft )"