bin/db-switch

db-switch.rb

#!/usr/bin/env ruby

require(Dir.pwd + "/config/environment")

ActiveRecord::Base.configurations.configs_for(env_name: ActiveRecord::Tasks::DatabaseTasks.env).each do |db_config|
  ActiveRecord::Base.establish_connection(db_config.config)

  context = ActiveRecord::Base.connection.migration_context

  missing_migrations = []

  context.migrations_status.each do |status, version, name|
    # We're only interested in migrations that are currently applied
    next unless status == "up"

    # We're only interested in migrations being displayed as "***** NO FILE *****"
    next unless name.start_with?("*")

    raise "Unexpected version format: #{version.inspect} is not numeric" unless version =~ /\A[0-9]+\z/

    missing_migrations << version
  end

  next if missing_migrations.empty?


  puts
  puts "Missing migrations in #{db_config.spec_name}:"
  puts missing_migrations.map { |s| "  #{s}" }
  puts

  migration_sha = {}
  missing_migrations.each do |version|
    migration_sha[version] = nil
  end

  puts "% git rev-list --walk-reflogs HEAD"
  IO.popen("git rev-list --walk-reflogs HEAD") do |sha_list|
    until migration_sha.values.all?
      sha = sha_list.gets.chomp

      newly_found = []

      paths = Shellwords.join([*context.migrations_paths].map { |path| "#{path}/" })
      puts %(% git ls-tree --name-only #{sha} -- #{paths})
      migrate_files = %x(git ls-tree --name-only #{sha} -- #{paths}).lines.map(&:chomp)

      migrate_files.each do |filename|
        version = File.basename(filename).split("_", 2).first

        if migration_sha.key?(version) && migration_sha[version].nil?
          migration_sha[version] = [sha, filename]
          newly_found << version
        end
      end

      puts "    found #{newly_found.sort.join(", ")}" unless newly_found.empty?
    end
  end

  migration_files = []

  missing_migrations.each do |version|
    next unless migration_sha[version]

    sha, filename = migration_sha[version]

    puts %(% git cat-file blob #{sha}:#{Shellwords.escape filename})
    migration_script = %x(git cat-file blob #{sha}:#{Shellwords.escape filename})

    eval migration_script, nil, filename, 1
    $LOADED_FEATURES << File.expand_path(filename)

    migration_files << filename
  end

  puts

  dummy_context = ActiveRecord::MigrationContext.new(nil, ActiveRecord::Base.connection.migration_context.schema_migration)
  class << dummy_context
    attr_accessor :migration_files
  end
  dummy_context.migration_files = migration_files

  dummy_context.down

  if ActiveRecord::Base.dump_schema_after_migration
    ActiveRecord::Tasks::DatabaseTasks.dump_schema(db_config)
  end
end