DatabaseConsistency

The main goal of the project is to provide an easy way to check the consistency of the database constraints with the application validations.

Currently, we can:

• find missing null constraints (ColumnPresenceChecker)
• find missing length validations (LengthConstraintChecker)
• find missing presence validations (NullConstraintChecker)
• find missing foreign keys for BelongsTo associations (BelongsToPresenceChecker)
• find missing unique indexes for uniqueness validation (MissingUniqueIndexChecker)
• find missing index for HasOne and HasMany associations (MissingIndexChecker)

We also provide flexible configuration (example) and integrations

We support the following databases: SQLite3, PostgreSQL and MySQL. We support any framework or pure ruby which uses ActiveRecord.

Check out the database_validations to have faster and reliable uniqueness validations and BelongsTo associations using ActiveRecord.

Installation

Add this line to your application's Gemfile:

gem 'database_consistency', group: :development, require: false

And then execute:

bundle install

Usage

In the root directory of your Rails project just run bundle exec database_consistency.

Non Rails projects

For any other framework or pure ruby, you can copy the following code and create a file database_consistency_runner.rb.

# First of all, you need to load all models
# The following example is for Rails, but it can be anything  
require_relative 'config/environment'
Rails.application.eager_load!

# Now start the check
require 'database_consistency'
result = DatabaseConsistency.run
exit result

Now, just start the script: bundle exec ruby database_consistency_runner.

Configuration

You can configure the gem to skip some of its checks using .database_consistency.yml file. By default, every checker is enabled.

There is also a way to pass settings through environment variables (they will have priority over settings from .database_consistency.yml file). You can pass LOG_LEVEL=DEBUG and/or COLOR=1.

How it works?

ColumnPresenceChecker

Imagine your model has a validates :email, presence: true validation on some field but doesn't have not-null constraint in the database. In that case, your model's definition assumes (in most cases) you won't have null values in the database but it's possible to skip validations or directly write improper data in the table.

To avoid the inconsistency and be always sure your value won't be null you should add not-null constraint.

allow_nil/allow_blank/if/unless	database	status
at least one provided	required	fail
at least one provided	optional	ok
all missing	required	ok
all missing	optional	fail

LengthConstraintChecker

Imagine your model has limit constraint on some field in the database but doesn't have validates :email, length: { maximum: <VALUE> } validation. In that case, you're sure that you won't have values with exceeded length in the database. But each attempt to save the a value with exceeded length on that field will be rolled back with error raised and without errors on your object. Mostly, you'd like to catch it properly and for that length validator exists.

We fail if any of following conditions are satisfied:

• there is no length validation for the column
• there is length validation for the column but with greater limit than in database, so some values will still throw an error

NullConstraintChecker

Imagine your model has not-null constraint on some field in the database but doesn't have validates :email, presence: true validation. In that case, you're sure that you won't have null values in the database. But each attempt to save the nil value on that field will be rolled back with error raised and without errors on your object. Mostly, you'd like to catch it properly and for that presence validator exists.

We fail if the column satisfies the following conditions:

• column is required in the database
• column is not a primary key (we don't need need presence validators for primary keys)
• model records timestamps and column's name is not created_at or updated_at
• column is not used for any Presence or Inclusion validators or BelongsTo association
• column has not a default value
• column has not a default function

BelongsToPresenceChecker

Imagine your model has a validates :user, presence: true or belongs_to :user, optional: false (since Rails 5+ optional is false by default). In both cases, you assume your instance has a persisted relation with another model which can be not true. For example, we can skip validations or remove connected instance after insert and etc. So, to keep your data consistency, in most cases, you should define a foreign key constraint in the database. It will ensure your relation exists.

We fail if the following conditions are satisfied:

• belongs_to association is not polymorphic
• belongs_to association has presence validator
• there is no foreign key constraint

MissingUniqueIndexChecker

Imagine your model has a validates :email, uniqueness: true validation but has no unique index in the database. As general problem your validation can be skipped or there is possible duplicates insert because of race condition. To keep your data consistent you should cover your validation with proper unique index in the database (if possible). It will ensure you don't have duplicates.

We fail if the following conditions are satisfied:

• there is no unique index for the uniqueness validation

MissingIndexChecker

Imagine your model has a has_one :user association but has no index in the database. In this case querying the database to get the associated instance can be very inefficient. Mostly, you'll need an index to process such queries fast.

We fail if the following conditions are satisfied:

• there is no index for the HasOne or HasMany association
• it has a through option

Example

$ bundle exec database_consistency
fail User code column is required in the database but do not have presence validator
fail Company note column has limit in the database but do not have length validator
fail User phone column should be required in the database
fail User name column is required but there is possible null value insert
fail User name+email model should have proper unique index in the database
fail User company model should have proper foreign key in the database
fail Company user associated model should have proper index in the database
fail Country users associated model should have proper index in the database

See rails-example project for more details.

Integrations

Configuration example for overcommit gem.

PreCommit:
  DatabaseConsistency:
    enabled: true
    quiet: false
    command: ['bundle', 'exec', 'database_consistency']

Development

After checking out the repo, run bundle install to install dependencies. You need to have installed and running postgresql and mysql. And for each adapter manually create a database called database_consistency_test accessible by your local user.

MySQL

# user is your local user from $whoami command
mysql -uroot --password
mysql> CREATE DATABASE database_consistency_test;
mysql> CREATE USER user@localhost IDENTIFIED BY '';
mysql> GRANT ALL PRIVILEGES ON database_consistency_test.* TO user@localhost;

PostgreSQL

psql postgres
postgres=# CREATE DATABASE database_consistency_test;

Then, run bundle exec rspec to run the tests.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

Code of Conduct

Everyone interacting in the DatabaseConsistency project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

Changelog

DatabaseConsistency's changelog is available here.

Copyright

Copyright (c) Evgeniy Demin. See LICENSE.txt for further details.