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ActiveRecord adapter for MySQL that report warnings.

The main usage is to progressively identify and fix MySQL warnings generated by legacy rails applications, and ultimately enable strict mode.

Alternatively it can be used to treat all MySQL warnings as errors.


Add this line to your application's Gemfile:

gem 'activerecord-pedantmysql2-adapter'

And then execute:

$ bundle

Finally in your database.yml:

adapter: pedant_mysql2

Or if you're using DATABASE_URL or the url key in database.yml, you can use the pedant-mysql2 URL scheme:

url: pedant-mysql2://host/database


By default it will raise warnings as errors. But you can define any behaviour yourself in an initializer.

You can report them to your exception tracker:

  PedantMysql2.on_warning = lambda { |warning| Airbrake.notify(warning) }

or totally silence them:


and to restore it to raising warnings as errors:


You can easily whitelist some types of warnings:

PedantMysql2.ignore(/Some warning I don't care about/i)

If you want to silence warnings for a limited scope, you can capture the warnings:

warnings = PedantMysql2.capture_warnings do
  # perform query that may raise an error you want to stifle


This gem is tested to be thread safe with a couple known exceptions.

PedantMysql2.ignore is not thread safe and should only be called during initialization of your app. Changing this within a thread while another is updating it could be problematic. PedantMysql2.on_warning= is not thread safe, this should also be called only during initialization.

If you find any other parts that are not thread-safe, please create an issue or PR.


Setting up the development environment is very straightforward. In order to keep the test as simple as possible we rely on your MySQL database to have a travis user and a pedant_mysql2_test database.

You can set this up easily using the following commands as your root MySQL user:

CREATE USER 'travis'@'localhost';
CREATE DATABASE pedant_mysql2_test;
GRANT ALL PRIVILEGES ON pedant_mysql2_test.* TO 'travis'@'localhost';


  1. Fork it ( )
  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 new Pull Request