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.

Answer 1

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.

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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.

Answer 2

You can use this command

rake db:reset

Answer 3

In my Rails 5 environment.

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

Or all together.

rails db:purge db:migrate db:seed