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Valle automatically creates validations for the minimum and maximum values of fields in your ActiveRecord model(s). No more worrying that string lengths or ID values will exceed the permissible DB limits!

For example, the maximum length of the string type in PostgreSQL is 255. Valle creates the following validator for you, so you no longer need to write it by hand:

validates :field_name, length: { maximum: 255 }

Note: If you do not do this (and usually you are) and try to enter 2147483648 into a field of type integer (see the Numeric types section of PostgreSQL docs), you will get a 500 error.


PG::Error: ERROR:  value "2147483648" is out of range for type integer
: SELECT  "users".* FROM "users"  WHERE "users"."id" = $1 LIMIT 1

Supported ActiveRecord field types

  • :primary_key
  • :integer
  • :string
  • :text


Add this line to your application's Gemfile:

gem 'valle'

And then execute:

$ bundle

Or install it yourself:

$ gem install valle

If you are using other framework than Rails (e.g. Sinatra), call Valle::Hooks.init method during the boot process.


By default, this gem adds validators to all your ActiveRecord models. If that is the behavior you want, you don't need to tweak it.

However, you can skip some of them by adding the file config/initializers/valle.rb containing:

Valle.configure do |config|
  config.exclude_models = %w(Post)

Also, you can disable it temporarily by setting the enabled configuration option to false.

Valle.configure do |config|
  config.enabled = false

Disabling Valle on specific attributes

There are cases where you need to skip validation for a particular attribute (see #4). For example, CarrierWave stores images temporarily in attributes, so calling save on them will fail because of its LengthValidator (255 characters maximum). You can disable Valle for such fields using the exclude_attributes configuration option:

Valle.configure do |config|
  config.exclude_attributes = {
    'User' => %w(image)


There is a similar gem, called validates_lengths_from_database. It solves only one part of the problem — applicable to strings. Valle, however, is designed to work with all possible field types.


Docker container

If you have docker installed on your machine, you can spin up a sandbox and run test suite in a few seconds:

$ docker build -t valle .
$ docker run -it --rm -v "$PWD":/usr/src/lib valle bundle exec rake

Or simply use Makefile commands:

$ make docker_build
$ make docker_test

Debugging Cucumber tests

Uncomment @announce-output tag at the top of the .feature file.


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Added some feature')
  4. Run test suite (rake test_suite)
  5. Push to the branch (git push origin my-new-feature)
  6. Create new Pull Request


Original authors:

Thank you to all our amazing contributors!


Valle is released under the MIT License.

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