govuk-design-system-rails

GOV.UK Design System

This gem contains a Rails engine containing a Ruby on Rails port of some GOV.UK Design System components.

It was originally extracted from Ruby applications built by the Office for Product Safety and Standards (see: https://github.com/UKGovernmentBEIS/beis-opss/pull/1374) and is by no means complete. Not every component is implemented and some components may not behave in exactly the same way as the originals. The project does aim for feature parity and PRs are welcome.

Compatibility

You must include the govuk-frontend assets (CSS, JS, images, etc.) in your application in order to make use of this library. These assets are not bundled with this gem. This gem aims for parity with a specific version of the govuk-frontend library.

This gem's version	Compatible with govuk-frontend version
0.9.7	4.3.1
0.9.0	4.1.0
0.8.2	3.14.0

Installation

Add the following to your project's Gemfile:

gem "govuk-design-system-rails"

and run bundle install

Design System Components

The GOV.UK design system provides a reference implementation of its components in Nunjucks, which are unfortunately not supported on Ruby. In lieu of that, we are implementing ERB versions of the components that can be used throughout the applications.

Component implementations

Component implementations can be found in the components directory. They try to follow the nunjucks implementations as close as possible. In particular, we are keeping the interface the same (param names etc.) to make translating code between the macros usage and our implementation as close as possible. This means that we can use the documentation provided by design system for macro options, e.g. see macro options for radios

Notable differences from nunjucks:

• we are not allowing unescaped html in html attributes. Instead, the expected use-case is to build the required html and capture it, e.g.:

  <% html = capture do %>
    <h3>Custom html content</h3>
  <% end %>
  <%= govukLabel html: html, for: "someId" %>
  

  This renders most text and html attributes functionally identical, but we are choosing to keep both for consistency with nunjucks templates
• We extended the govukSelect component to streamline using it as accessible autocomplete component. Our version accepts extra options:
  • is_autocomplete, when true, makes the select an accessible autocomplete
  • show_all_values, when true and is_autocomplete true, makes the autocomplete show all values, as well as adds an 'x' to remove currently selected value.
• hidden fields in checkboxes, to account for rails checkboxes "gotcha". The default value is 0 but can be set through the 'unchecked_value' attribute. https://apidock.com/rails/ActionView/Helpers/FormHelper/check_box

Rails integration

To simplify working with rails form helpers, we are also providing a bit of "glue" which infers the values that it can from the form object and converts them into appropriate params for the view components. Those can be found in the form_components directory.

The intent of keeping this "glue" separate from the component implementations is to make keeping the components up to date with the corresponding macros as simple as possible.

The helpers accept a form parameter, when this is present, the form_components version of a component is used.