discourse/plugins/discourse-calendar/db/migrate/20200226183018_create_calendar_events.rb

# frozen_string_literal: true

class CreateCalendarEvents < ActiveRecord::Migration[5.2]
  def change
    create_table :calendar_events do |t|
      t.integer :topic_id, null: false
      t.integer :post_id
      t.integer :post_number
      t.integer :user_id
      t.string :username
      t.string :description
      t.datetime :start_date, null: false
      t.datetime :end_date
      t.string :recurrence
      t.string :region
      t.timestamps

      t.index :topic_id
      t.index :post_id
      t.index :user_id
    end

    # Data structure stored in 'calendar-details' custom field is complex and
    # difficult to transform using SQL only. It is safer to extract all calendar
    # events again.
    begin
      calendar_topic_ids = DB.query_single(<<~SQL)
        SELECT topic_id
        FROM posts
        JOIN post_custom_fields ON posts.id = post_custom_fields.post_id
        WHERE post_custom_fields.name = 'calendar-details'
           OR post_custom_fields.name = 'calendar-holidays'
      SQL

      # this is not ideal we should be using SQL here but this will work around bad schema
      ActiveRecord::Base.connection.query_cache.clear
      Post.reset_column_information # rubocop:disable Discourse/NoResetColumnInformationInMigrations
      Post.where(topic_id: calendar_topic_ids).each { |post| CalendarEvent.update(post) }

      execute "DELETE FROM post_custom_fields WHERE name = 'calendar-details' OR name = 'calendar-holidays'"
    rescue => e
      STDERR.puts e.message
      STDERR.puts e.backtrace.join("\n")
    end
  end
end