How to delete all data from all tables in Rails?

Question

I can do Post.delete_all to delete all my posts, but what if I want to delete all posts, comments, blogs, etc.?

How do I iterate over all my models and

Answer 1

You can have finer control with:

rake db:drop:all

And then create the database without running the migrations,

rake db:create:all

Then run all your migrations,

rake db:migrate 

You can also do:

mysqladmin drop databasename

Answer 2

In Rails 6, you can do rails db:truncate_all to remove all data without dropping any tables.

If you would like to seed your db after that, you could also do rails db:seed:replant to truncate all data and seed database

Answer 3

rake db:reset 

It recreates your table from migrations.

As suggested in the comments, a faster way to do it (but you have to add a new rake task) is:

namespace :db do
  desc "Truncate all tables"
  task :truncate => :environment do
    conn = ActiveRecord::Base.connection
    tables = conn.execute("show tables").map { |r| r[0] }
    tables.delete "schema_migrations"
    tables.each { |t| conn.execute("TRUNCATE #{t}") }
  end
end

Response copied from: answer on SO.

Answer 4

You could list all the models in the seed-file (seeds.rb), and simply run

rake db:seed

The seed file would then look something like this:

Model1.delete_all
Model2.delete_all
Model3.delete_all
Model4.delete_all
Model5.delete_all
Model6.delete_all
Model7.delete_all

...

rake db:reset is too much for your job here. That will completely kill off your database and rebuild it from scratch, running all migrations etc. To run the seed command is faster.

Answer 5

# fast truncation of all tables that need truncations (select is 10x faster then truncate)
# http://grosser.it/2012/07/03/rubyactiverecord-fastest-way-to-truncate-test-database/
def truncate_all_tables
  connection = ActiveRecord::Base.connection
  connection.disable_referential_integrity do
    connection.tables.each do |table_name|
      next if connection.select_value("SELECT count(*) FROM #{table_name}") == 0
      connection.execute("TRUNCATE TABLE #{table_name}")
    end
  end
end

Answer 6

If you want to delete only the data without touching the tables while using it inside your application or rails console :

Rails.application.eager_load!
ActiveRecord::Base.connection.disable_referential_integrity do
  ApplicationRecord.descendants.each do |model|
    model.delete_all
  end
end

With this code, you don't have to bother with referencing manually your models and/or with foreign key constraints (thanks to disable_referential_integrity).
ApplicationRecord.descendants returns only true application models unlike ActiveRecord::Base.descendants (no more ApplicationRecord, schema_migrations and ar_internal_metadata).