ActiveRecord View Migrations

view_migrations.md

Rake task to perform "view migrations" for using SQL Views with Rails. Avoids the need to copy or re-run multiple migrations when changes are made to queries providing view data.

Usage: rake db:views:load

Place SQL create statement for each view in a file as db/views/<view_name>.sql. Optionally include a numeric prefix such as 01_first_view.sql to order views that may have dependencies.

namespace :db do
  namespace :views do
    desc "Execute all stored View statements on DB connection"
    task :load => :environment do
      ActiveRecord::Base.establish_connection(ENV['RAILS_ENV'])
      
      views = Dir.glob("#{Rails.root.join('db', 'views')}/*")

      # First, drop all of the views the hard way
      views.each do |view|
        view_name = File.basename(view, '.sql').gsub(/^\d+_/, '')
        ActiveRecord::Base.connection.execute("DROP VIEW IF EXISTS #{view_name} CASCADE;")
      end

      # And now execute the create statements
      views.each do |view|
        view_name = File.basename(view, '.sql').gsub(/^\d+_/, '')
        sql = IO.read(Rails.root.join('db', 'views', view))
        ActiveRecord::Base.connection.execute(sql)
        puts "Created database view for #{view_name}"
      end
    end
  end
end