ActiveRecord::DatabaseValidations

An ActiveRecord extension that lets you use your database validations.

• Converts ActiveRecord::StatementInvalid related to database validations on ActiveRecord::Base#save into a validation error.
• Quickly add pre-save validations according to your database validations.

Currently supports mysql and postgresql. Feel free to help support more.

Add this line to your application's Gemfile:

gem 'activerecord-database_validations'

And then execute:

$ bundle

Or install it yourself as:

$ gem install activerecord-database_validations

This extension is included into ActiveRecord::Base automatically, so all you need to do is use it.

# == Schema Information
#
# Table name: users
#
#  id              :integer          not null, primary key
#  username        :string           not null
#  group_id        :integer
#  inviter_id      :integer
#
# Indexes
#
#  index_boards_on_group_id_and_username (group_id,username) UNIQUE
#
# Foreign Keys
#
#  add_foreign_key "users", "users", column: "inviter_id"
#

class User < ActiveRecord::Base
  validates_database
  # This is an alias to (which can be used separately):
  # validates_database_not_null
  # validates_database_unique
  # validates_database_foreign_key
end

# validates_database_not_null
u = User.new
u.valid?
=> false
u.errors.messages
=> { :username => ["can't be blank"] }

# validates_database_unique
u1 = User.new(group_id: 5, username: "somename")
u1.save
=> true
u2 = User.new(group_id: 5, username: "somename")
u2.save
=> false
u2.errors.messages
=> { :username => ["has already been taken"] }

# validates_database_foreign_key
u1 = User.new(username: "anothername", inviter_id: -1)
u1.save
=> false
u1.errors.messages
=> { inviter_id: ["is not included in the list"] }

As mentioned above you can use a specific validation type, and any of these validates_database* methods can also receive the :message option (and sometimes other validation options depending on the back-end used to preform the actual validation).

You don't really have to do anything but specify the right validations in your schema (or migrations). On knows database validation errors ActiveRecord::Base#save will return false, ActiveRecord::Base#save! will raise an ActiveRecord::RecordInvalid, and ActiveRecord::Base#errors will show the error on the specific field.

• Pre-save does not handle race conditions (::validates_database_unique and ::validates_database_foreign_key). This is the actual reason behind using database validations. So between the time the check was made and the time the record was saved:
  • There could be an extra record that would make the new record fail the unique validation.
  • The referenced record could have been deleted that would make the foreign key validation fail.
• On-save only happens if the application validations succeeded. This means you will not see the error on the failing field (in ActiveRecord::Base#errors). That said, it will also only show one error, so if two database validations failed only one field will show an error.
• Pre-save does an extra query for ::validates_database_unique and ::validates_database_foreign_key, so if time is of the essence let the on-save validation catch the error, otherwise it's best to add the full ::validates_database to your model.

• You do not have any control over on-save validations, the logic is applied if you want it or not on every ActiveRecord::Base. If you can think of a reason why it shouldn't, please file an issue.
• When the unique index is on multiple columns mysql and postgresql (and maybe others) do not fail if any of the columns is nil. With this in mind, the error is added on the last column of the index.

To run the tests you must have a user and a database set up in the supported databases.

As MySQL root:

CREATE USER 'gemtester'@'localhost';
CREATE DATABASE activerecord_database_validations_test;
GRANT ALL ON `activerecord_database_validations_test`.* TO 'gemtester'@'localhost';

As Postgresql root:

CREATE USER gemtester;
CREATE DATABASE activerecord_database_validations_test;
GRANT ALL PRIVILEGES ON DATABASE activerecord_database_validations_test TO gemtester;
\c activerecord_database_validations_test postgres
GRANT ALL ON SCHEMA public TO gemtester;

After checking out the repo, run bin/setup to install dependencies. Then, run bin/console for an interactive prompt that will allow you to experiment.

1. Fork it (https://github.com/odedniv/activerecord-database_validations/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

This consists of 3 simple steps:

1. Add an adapter gem as a development dependency in activerecord-database_validations.gemspec.
2. Add adapter configuration to spec/db/adapters.rb.
3. Add new patterns for error matching in lib/activerecord/database_validations/rescues.rb.

Of course make sure rspec doesn't fail, and create a new Pull Request!