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 to delete_all over all my models and run the delete_all method?

Answer 1

 rake db:reset 

He recreates the table from the migrations.

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

 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 

Answer copied from: answer to SO .

Answer 2

You can have finer control with:

 rake db:drop:all 

And then create the database without performing the migration,

 rake db:create:all 

Then run all your migrations,

 rake db:migrate 

You can also do:

 mysqladmin drop databasename 

Answer 3

If you are trying to do this from code instead of the command line, say, from the Test::Unit::TestCase#teardown , you can do either

 class MyTest < Test::Unit::TestCase def teardown ActiveRecord::Base.subclasses.each(&:delete_all) end end 

or

 class MyTest < Test::Unit::TestCase def teardown Rake::Task['db:reset'].invoke end end 

I warn you: although not very fast. You are certainly better off conducting transactional tests.

Answer 4

If you just want to start a new job with a new set of empty tables, you can first make sure that you have a modern schema definition in db / schema.rb:

 rake db:schema:dump 

and then:

 rake db:schema:load 

which has the effect of dropping tables and then re-creating them without using your entire migration battery.

Answer 5

A faster way to simply delete table rows is to use the TRUNCATE command.

Many other answers seem to ignore the difference between deleting rows and rolling back the table. Deleting a table destroys table data and schema; that you need to take additional steps to recreate the tables. Sean McLeary's answer was the best I've seen, so I used it as a starting point. However, I think it is better to use the TRUNCATE command, because it should be faster, and also resets keys with auto-increment. Also, using map instead of each shortens the code a bit.

 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 

Answer 6

rails db:purge

was recently added to ActiveRecord in the main rail branch 4.2.0.alpha

https://github.com/rails/rails/commit/e2f232aba15937a4b9d14bd91e0392c6d55be58d

Answer 7

You can list all the models in the seed file (seeds.rb) and just run

 rake db:seed 

Then the seed file will 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 too much for your work here. This will completely destroy your database and rebuild it from scratch, doing all the migrations, etc. To run the seed command faster.

Answer 8

Accepted answer with Postgres db:

 namespace :db do desc "Truncate all tables" task :truncate => :environment do conn = ActiveRecord::Base.connection postgres = "SELECT tablename FROM pg_catalog.pg_tables WHERE schemaname='public'" tables = conn.execute(postgres).map { |r| r['tablename'] } tables.delete "schema_migrations" tables.each { |t| conn.execute("TRUNCATE \"#{t}\"") } end end 

Answer 9

This will work for Rails 4.

 (ActiveRecord::Base.connection.tables - ['schema_migrations']).each do |table| table.classify.constantize.destroy_all end 

Answer 10

If you want to delete only data without touching the tables, 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 worry about manually referencing your models and / or with foreign key constraints (due to disabling integration_refractivity).
ApplicationRecord.descendants returns only true application models, unlike ActiveRecord :: Base.descendants (no more than ApplicationRecord, schema_migrations and ar_internal_metadata).

Answer 11

We lost our place in Stack Overflow without mentioning the database_cleaner gem :

Database Cleaner is a set of strategies for cleaning your database in Ruby. The initial use was to ensure a clean state during testing. Each strategy is a small code, but it is the code that is usually required in any ruby ​​application that tests the database.

According to the “strategy”, Mr. Maby means: truncation, transaction and deletion.

ActiveRecord, DataMapper, Sequel, MongoMapper, Mongoid and CouchPotato are supported.

The following is a snippet of code from "Cleaning the README Database" :

 require 'database_cleaner' DatabaseCleaner.strategy = :truncation # then, whenever you need to clean the DB DatabaseCleaner.clean 

Answer 12

 # 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 13

I know this is an old question, but I thought it might help someone. This is a very quick way to clear all data from a database.

 tables = [] ActiveRecord::Base.connection.execute("show tables").each { |r| tables << r[0] } tables = tables - ["schema_migrations"] tables.each do |table| ActiveRecord::Base.connection.execute("DELETE FROM #{table} WHERE 1 = 1") end 

I use this technique in certain specifications in the after(:all) block. This is much faster and more effective than any of the Rake Rake tasks for cleaning, migrating, reselling the database.

BTW: I am sure this will most likely fail if you apply foreign key constraints on the database side.

Answer 14

My 50 cents for cleaning db and the ability to start the migration again (in cases where you cannot delete the database, for example AWS RDS):

 # get connection conn = ActiveRecord::Base.connection # find all tables needed to be removed tables = conn.execute("SELECT * FROM pg_catalog.pg_tables WHERE schemaname='public' AND tablename<>'schema_migrations'").to_a.map { |r| r['tablename'] } # remove all tables except schema_migrations tables.each { |t| conn.execute("DROP TABLE #{t}") } # clean migrations table conn.execute("TRUNCATE TABLE schema_migrations") 

And now you can run rake db:migrate so that your db is in a clean state.

Answer 15

In Rails 6, you can do rails db:truncate_all to delete all data without deleting the tables.

If after that you want to populate your database, you can also do rails db:seed:replant to truncate all the data and the database.

Answer 16

Based on @Vlad Zloteanu's answer, here is a version for deleting all tables, saving user records and login sessions along with some meta-information. Feel free to customize the list of tables to suit your requirements.

 # lib/tasks/db/truncate.rake namespace :db do desc 'Truncate all tables except users state and meta' task truncate: :environment do conn = ActiveRecord::Base.connection tables = conn.tables - %w[ sessions users roles users_roles schema_migrations ar_internal_metadata ] tables.each { |t| conn.execute("TRUNCATE #{t}") } puts "Truncated tables\n================\n#{tables.sort.join("\n")}" end end