How to clear database before seeding in rails

Question

Is there a simple line of code I can include at the top of my seed file to clear out each table before inserting new seed data without running any rake commands to rollback tables or databases?

I was thinking something like:

[Foo, Bar].each{|class| class.destroy_all}

The point is I want to add new data where each new insertion starts from id: 1. What I want to avoid is deleting a table with 100 rows and when I add new data it's starting from 101.

I'm using SQLite locally and PostgreSQL through Heroku. This is my first SO question... how do I mark it answered? Also, after doing some more research, I found the database_cleaner gem whereby I just added `DatabaseCleaner.clean_with(:truncation)` at the top of my seed file and Bingo! :) Thanks for the help Vishal! — Jesse Novotny, Sep 23 '16 at 18:01
[How to mark question as answered](http://meta.stackexchange.com/questions/5234/how-does-accepting-an-answer-work) — Vishal Nagda, Sep 24 '16 at 11:36

score 11 · Accepted Answer · edited Jan 03 '17 at 16:30

Updated Answer

You've to install (OR you can add gem 'database_cleaner' to your Gemfile) a GEM called Database Cleaner which helps to clean your database without affecting your database schema._

To clean your database each time whenever you do rake db:seed then paste

# updated
require 'database_cleaner'

DatabaseCleaner.clean_with(:truncation)

on the top of your seed file. It'll clear your database and start count from 1 again.

Disclaimer : This updated answer is tested, and working perfectly in my system.

===========================================================================

Previous Untested Answer

Ya you can do that but it's depends on which database you're using.

Below I'm giving solution for some popular DBs.

In MySQL, TRUNCATE table; deletes all rows and resets the auto increment counter.

In PostgreSQL, it does not do this automatically. You can use TRUNCATE TABLE table RESTART IDENTITY;.

In SQLite, there is no TRUNCATE statement, instead, it's

DELETE FROM table;
DELETE FROM sqlite_sequence WHERE name='table';

You can also try this

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

You can select any one of the solution & implement it to your seed file.

I hope this will help you... ;)

Disclaimer : I've share my knowledge for the purpose of your help, but this solution was didn't tested.

`ActiveRecord::Base.connection.tables` could delete your migrations table... — Jay Killeen, Feb 16 '20 at 04:26

score 2 · Answer 2 · answered Sep 22 '16 at 18:35

2

You can use this command

rake db:reset

answered Sep 22 '16 at 18:35

Deepak Mahakale

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Ian Purton · Answer 3 · 2018-01-31T12:39:37.230

2

In my Rails 5 environment.

rails db:purge
rails db:migrate
rails db:seed

Or all together.

rails db:purge db:migrate db:seed

edited Jan 31 '18 at 12:39

answered Jan 05 '18 at 10:02

Ian Purton

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Nice. Don't forget you can chain these like `rails db:foo db:bar` – Jesse Novotny Jan 10 '18 at 18:33

score 1 · Answer 4 · answered May 24 '23 at 14:52

1

As of Rails 6, you can run

rails db:seed:replant

which will truncate the database before seeding.

answered May 24 '23 at 14:52

supernikio2

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score 0 · Answer 5 · answered Sep 22 '16 at 17:19

0

Before doing the rake db:seed.

rake db:purge

has recently been added to ActiveRecord in the master branch of rails 4.2.0.alpha

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

answered Sep 22 '16 at 17:19

Charan Kumar Borra

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Not sure if this resets the counts for new ids, but this is how to do it for sqlite3: `sql = "delete from sqlite_sequence where name = '#{table}'";ActiveRecord::Base.connection.execute(sql)` – Teddy Sep 22 '16 at 18:16

score 0 · Answer 6 · answered Sep 23 '16 at 18:02

After doing some more research on this topic, I found the 'database_cleaner' gem. After installing, I simply added DatabaseCleaner.clean_with(:truncation) at the top of my seed.rb and Bingo! It seems to have worked locally running SQLite and with PostgreSQL on Heroku. Thanks for all the input everyone! :)

shilovk · Answer 7 · 2021-04-25T18:24:01.463

Without removing(dropping) database:

rollback all migrations, for example if they < 1000 and after migrate and seed

STEP=1000 rails db:rollback && rails db:migrate && rails db:seed

or

rails db:purge && rails db:migrate && rails db:seed

With removing(dropping) database:

remove(drop) database + create database + migrate + seed

rails db:reset

or

rails db:drop && rails db:create && rails db:migrate && rails db:seed

How to clear database before seeding in rails

7 Answers7