Purge or recreate a Ruby on Rails database - ruby-on-rails

Question

I have a dev Ruby on Rails database full of data. I want to delete everything and rebuild the database. I'm thinking of using something like:
rake db:recreate
Is this possible?

Answer 1

I know two ways to do this:
This will reset your database and reload your current schema with all:
rake db:reset db:migrate
This will destroy your db and then create it and then migrate your current schema:
rake db:drop db:create db:migrate
All data will be lost in both scenarios.

Answer 2

On Rails 4, all needed is
$ rake db:schema:load
That would delete the entire contents on your DB and recreate the schema from your schema.rb file, without having to apply all migrations one by one.

Answer 3

I use the following one liner in Terminal.
$ rake db:drop && rake db:create && rake db:migrate && rake db:schema:dump && rake db:test:prepare
I put this as a shell alias and named it remigrate
By now, you can easily "chain" Rails tasks:
$ rake db:drop db:create db:migrate db:schema:dump db:test:prepare # db:test:prepare no longer available since Rails 4.1.0.rc1+

Answer 4

Update: In Rails 5, this command will be accessible through this command:
rails db:purge db:create db:migrate RAILS_ENV=test
As of the newest rails 4.2 release you can now run:
rake db:purge
Source: commit
# desc "Empty the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:drop:all to drop all databases in the config). Without RAILS_ENV it defaults to purging the development and test databases."
task :purge => [:load_config] do
ActiveRecord::Tasks::DatabaseTasks.purge_current
end
It can be used together like mentioned above:
rake db:purge db:create db:migrate RAILS_ENV=test

Answer 5

Depending on what you're wanting, you can use…
rake db:create
…to build the database from scratch from config/database.yml, or…
rake db:schema:load
…to build the database from scratch from your schema.rb file.

Answer 6

From the command line run
rake db:migrate:reset

Answer 7

In Rails 6 there is a convenient way for resetting DB and planting seeds again:
rails db:seed:replant # Truncates tables of each database for current environment and loads the seeds
https://weblog.rubyonrails.org/2019/3/15/this-week-in-rails-security-fixes-bulk-insert-and-upsert-seeds-replanting/

Answer 8

Use like
rake db:drop db:create db:migrate db:seed
All in one line. This is faster since the environment doesn't get reloaded again and again.
db:drop - will drop database.
db:create - will create database (host/db/password will be taken from config/database.yml)
db:migrate - will run existing migrations from directory (db/migration/.rb)*.
db:seed - will run seed data possible from directory (db/migration/seed.rb)..
I usually prefer:
rake db:reset
to do all at once.
Cheers!

Answer 9

Just issue the sequence of the steps: drop the database, then re-create it again, migrate data, and if you have seeds, sow the database:
rake db:drop db:create db:migrate db:seed
Since the default environment for rake is development, in case if you see the exception in spec tests, you should re-create db for the test environment as follows:
RAILS_ENV=test rake db:drop db:create db:migrate
In most cases the test database is being sowed during the test procedures, so db:seed task action isn't required to be passed. Otherwise, you shall to prepare the database:
rake db:test:prepare
or
RAILS_ENV=test rake db:seed
Additionally, to use the recreate task you can add into Rakefile the following code:
namespace :db do
task :recreate => [ :drop, :create, :migrate ] do
if ENV[ 'RAILS_ENV' ] !~ /test|cucumber/
Rake::Task[ 'db:seed' ].invoke
end
end
end
Then issue:
rake db:recreate

Answer 10

You can manually do:
rake db:drop
rake db:create
rake db:migrate
Or just rake db:reset, which will run the above steps but will also run your db/seeds.rb file.
An added nuance is that rake db:reset loads directly from your schema.rb file as opposed to running all the migrations files again.
You data gets blown away in all cases.

Answer 11

You can use this following command line:
rake db:drop db:create db:migrate db:seed db:test:clone

Answer 12

To drop a particular database, you can do this on rails console:
$rails console
Loading development environment
1.9.3 > ActiveRecord::Migration.drop_table(:<table_name>)
1.9.3 > exit
And then migrate DB again
$bundle exec rake db:migrate

Answer 13

On rails 4.2, to remove all data but preserve the database
$ bin/rake db:purge && bin/rake db:schema:load
https://github.com/rails/rails/blob/4-2-stable/activerecord/CHANGELOG.md

Answer 14

You can use
db:reset - for run db:drop and db:setup or
db:migrate:reset - which runs db:drop, db:create and db:migrate.
dependent at you want to use exist schema.rb

Answer 15

According to Rails guide, this one liner should be used because it would load from the schema.rb instead of reloading the migration files one by one:
rake db:reset

Answer 16

Because in development , you will always want to recreate the database,you can define a rake task in your lib/tasks folder like that.
namespace :db do
task :all => [:environment, :drop, :create, :migrate] do
end
end
and in terminal you will run
rake db:all
it will rebuild your database

Answer 17

3 options, same result:
1. All steps:
$ rake db:drop # deletes the database for the current env
$ rake db:create # creates the database for the current env
$ rake db:schema:load # loads the schema already generated from schema.rb / erases data
$ rake db:seed # seed with initial data
2. Reset:
$ rake db:reset # drop / schema:load / seed
3. Migrate:reset:
$ rake db:migrate:reset # drop / create / migrate
$ rake db:seed
Notes:
If schema:load is used is faster than doing all migrations, but same result.
All data will be lost.
You can run multiple rakes in one line.
Works with rails 3.

Answer 18

I think the best way to run this command:
**rake db:reset** it does db:drop, db:setup
rake db:setup does db:create, db:schema:load, db:seed

Answer 19

Simply you can run
rake db:setup
It will drop database, create new database and populate db from seed if you created seed file with some data.

Answer 20

I use:
rails db:drop to delete the databases.
rails db:create to create the databases based on config/database.yml
The previous commands may be replaced with rails db:reset.
Don't forget to run rails db:migrate to run the migrations.

Answer 21

I've today made quite a few changes to my rails schema. I realised I needed an additional two models in a hierarchy and some others to be deleted. There were many little changes required to the models and controllers.
I added the two new models and created them, using:
rake db:migrate
Then I edited the schema.rb file. I manually removed the old models that were no longer required, changed the foreign key field as required and just reordered it a bit to make it clearer to me. I deleted all the migrations, and then re-ran the build via:
rake db:reset
It worked perfectly. All the data has to be reloaded, of course. Rails realised the migrations had been deleted and reset the high-water mark:
-- assume_migrated_upto_version(20121026094813, ["/Users/sean/rails/f4/db/migrate"])

Answer 22

TL;DR - I use this rake script during development to blow away everything, including the schema file, then rebuild directly from migration scripts. It rebuilds both dev and test databases simultaneously. It's the only way I've found to guarantee everything lines up the way I expect. Been using it for years without a problem.
# lib/tasks/db_rebuild.rake
require 'fileutils'
namespace :db do
desc "Create DB if it doesn't exist, then migrate and seed"
task :build do
Rake::Task["db:create"].invoke
Rake::Task["db:migrate"].invoke
Rake::Task["db:seed"].invoke
end
desc "Drop database and rebuild directly from migrations (ignores schema.rb)"
task :rebuild do
raise "Task not permitted in production." if ENV["RAILS_ENV"] == "production"
puts "*** Deleting schema.rb"
system "rm -f #{Rails.root.join("db", "schema.rb")}"
puts "*** Deleting seed lock files"
system "rm -f #{Rails.root.join("db", ".loaded*")}"
puts "*** Recreate #{ENV['RAILS_ENV']} database"
begin
Rake::Task['environment'].invoke
ActiveRecord::Base.connection
rescue ActiveRecord::NoDatabaseError
# database doesn't exist yet, just create it.
Rake::Task["db:build"].invoke
rescue Exception => e
raise e
else
Rake::Task["db:environment:set"].invoke
# https://github.com/rails/rails/issues/26319#issuecomment-244015760
# ENV["DISABLE_DATABASE_ENVIRONMENT_CHECK"] = '1'
Rake::Task["db:drop"].invoke
Rake::Task["db:build"].invoke
end
Rake::Task["db:retest"].invoke
end
desc "Recreate the test DB"
task :retest do
system("rake db:drop db:build RAILS_ENV=test")
end
end
Rationale - The problem with all the provided solutions is that native Rake tasks provided by Rails rely on schema.rb. When I am doing heavy data modeling, I make changes directly to the migration files; only after they've been committed upstream do we treat them as immutable. But if I make changes to the migration file, they aren't reflected in schema.rb.
The other problem is the distinction between dev and test environments. Rails db tasks handle them independently, but in my experience dev and test databases should always maintain parity, which means I had to run lots of duplicative database cleanup when developing.