Rake task to truncate all tables in Rails 3

Question

I would like to have a rake task for truncating all the tables. I have found one on the internet, but it is supposed only for Rails 2 and does not work for Rails 3 (problem is in getting a database connection).

rake db:reset is not an option, because I am using PostgreSQL and it also drops the user. Therefore migration fails. I only want to clear the data.

Do you guys have somehting for me?

Answer 1

I've found this via google, and then I got a much simpler solution than the one approved, so here it is: Use the database_cleaner gem. Here're the steps.

In your Gemfile (execute bundle after modifying):

gem 'database_cleaner' # you might want to limit this to the dev and staging group

With that gem in place, the statement DatabaseCleaner.clean_with :truncation will truncate the database. Adding it to a rake task is trivial:

# tasks/db/clean.rake

namespace :db do

  desc "Truncate all existing data"
  task :truncate => "db:load_config" do
    DatabaseCleaner.clean_with :truncation
  end

end

That's it. You can also use the DatabaseCleaner.clean_with :truncation line inside your db/seeds.rb file directly so that you don't forget to truncate the database before seeding.

Answer 2

So I edited the linked example into this:

namespace :db do
  desc "Truncate all existing data"
  task :truncate => "db:load_config" do
   begin
    config = ActiveRecord::Base.configurations[::Rails.env]
    ActiveRecord::Base.establish_connection
    case config["adapter"]
      when "mysql", "postgresql"
        ActiveRecord::Base.connection.tables.each do |table|
          ActiveRecord::Base.connection.execute("TRUNCATE #{table}")
        end
      when "sqlite", "sqlite3"
        ActiveRecord::Base.connection.tables.each do |table|
          ActiveRecord::Base.connection.execute("DELETE FROM #{table}")
          ActiveRecord::Base.connection.execute("DELETE FROM sqlite_sequence where name='#{table}'")
        end                                                                                                                               
       ActiveRecord::Base.connection.execute("VACUUM")
     end
    end
  end
end

This example is based on Chris Ledet's code bellow (thanks) and works with Rails 3.X.

Thanks for all hints.

Answer 3

According to Chris Ledet answer, this becomes much simpler:

ActiveRecord::Base.connection.tables.each do |table|
    ActiveRecord::Base.connection.execute("TRUNCATE TABLE #{table};")
end

Answer 4

To truncate db in Rails 6

rails db:truncate_all