db/migrate/20180113200119_move_species_to_revision.rb


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class MoveSpeciesToRevision < ActiveRecord::Migration[5.1]
  def up
    change_table :revisions do |t|
      t.references :species, null: true
    end

    Pokeviewer::Revision.all.each do |r|
      r.species_id = r.pokemon.species_id
      r.save!
    end

    remove_column :pokemon, :species_id

    change_column_null :revisions, :species_id, false

    add_foreign_key :revisions, :species,
      column: :species_id
  end

  def down
    def up
      change_table :pokemon do |t|
        t.references :species, null: true
      end

      Pokeviewer::Pokemon.all.each do |p|
        p.species_id = p.revisions.first.species_id
        p.save!
      end

      remove_column :revisions, :species_id

      change_column_null :pokemon, :species_id, false

      add_foreign_key :pokemon, :species,
        column: :species_id
    end
  end
end