Range Component Attributes

This gem creates attributes for the lower and upper bounds of a range on an ActiveRecord object. These attributes are automatically populated when a record is loaded and they are written to the underlying range when a record is saved. This makes it easier to work with ActiveRecord validations and form helpers.

Add this line to your application's Gemfile:

gem 'range_component_attributes'

And then execute:

$ bundle

Or install it yourself as:

$ gem install range_component_attributes

Include RangeComponentAttributes module in classes you want to work with range components. You can include it in ActiveRecord::Base or ApplicationRecord if you want it available in all models.

Use class method range_component_attributes to create range component attributes.

class Widget < ActiveRecord::Base
  include RangeComponentAttributes

  range_component_attributes :valid_dates,
    lower_name: :valid_from,
    upper_name: :valid_to,
    type_converter: DateConverter.new,
    crossed_bounds_message: "must be less than valid to"

  range_component_attributes :valid_prices,
    lower_name: :min_price,
    upper_name: :max_price,
    lower_type_converter: DecimalConverter.new,
    upper_type_converter: DecimalConverter.new(blank_value: Float::INFINITY)
end

widget = Widget.new min_price: "10", max_price: "20"
widget.valid_prices #=> 0.1e2...0.2e2

range_component_attributes creates attributes corresponding to the lower and upper bounds of range_name. lower_name and upper_name controls the names of these attributes.

type_converter is a callable object that converts its argument to the proper type. There are builtin type converters IntegerConverter, DecimalConverter, FloatConverter, and DateConverter.

In addition, lower_type_converter and upper_type_converter can be separately specified. This is especially useful when the attributeould behave differently for blank values. For example, the upper bound mant to consider a blank value as Float::INFINITY.

exclude_end controls whether the end is exclusive or not. Ranges are automatically normalized to this type. This is useful because PostgreSQL automatically normalizes ranges of discrete values to exclusive ends. e.g. [1, 10] becomes [1,11). RangeComponentAttributes will handle this so the exact bound values persist even when PostgreSQL has changed them.

Validations are automatically added that create an error if an assignment to bounds attribute fails due to a type conversion error. In addition, a validation checks that the lower bound is less than the upper bound. This error message can be customized by supplying crossed_bounds_message.

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

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.

To run the tests, first run rake db:setup. This creates a database called range_component_attributes_test and load database_structure.sql into it. Then run rake.

Bug reports and pull requests are welcome on GitHub at https://github.com/ccsalespro/range_component_attributes.

The gem is available as open source under the terms of the MIT License.