How to integrate with an existing database schema

You have an application with your own database schema, and you want to integrate it with Social Stream's migrations.

The most straightforward way is modifying the db/migrate/xxxxxxxxxxxxxx_create_social_stream.social_stream_base_engine.rb migration Social Stream has created in the installation process. This is an example:

class CreateSocialStream < ActiveRecord::Migration
  def up # You will probably have to redefine the method because this example is not revertable

    ...

    change_table "users" do |t| # change_table instead of create_table
      # Comment or remove the fields that you already have
      # t.string   "encrypted_password",     :limit => 128, :default => "",     :null => false
      # t.string   "password_salt"
      # t.string   "reset_password_token"
      # t.datetime "reset_password_sent_at"
      # t.datetime "remember_created_at"
      # t.integer  "sign_in_count",                         :default => 0
      # t.datetime "current_sign_in_at"
      # t.datetime "last_sign_in_at"
      # t.string   "current_sign_in_ip"
      # t.string   "last_sign_in_ip"
      # t.string   "authentication_token"
      # t.datetime "created_at",                                                :null => false
      # t.datetime "updated_at",                                                :null => false
      t.integer  "actor_id"
      t.string   "language"
    end

    # Reassign attributes so they are passed to actor association
    User.all.each do |u|
      u.name = u.read_attribute(:name)
      u.email = u.read_attribute(:email)
      u.actor!.created_at = u.created_at
      u.actor!.updated_at = u.updated_at
      u.save!
    end

    # Remove columns from users, actors' columns are used now
    change_table(:users) do |t|
      t.remove :name
      t.remove :email
    end

    User.reset_column_information

    ...
end