ViewComponent is a framework for creating reusable, testable & encapsulated view components with Ruby on Rails, without the need for a JavaScript framework like Vue. They are rendered server-side and can be seamlessly used with template languages like Haml.

For more information, see the official documentation or this introduction video.

Browse components with Lookbook

We have a Lookbook in http://gdk.test:3000/rails/lookbook (only available in development mode) to browse and interact with ViewComponent previews.

Pajamas components

Some of the components of our Pajamas design system are available as a ViewComponent in app/components/pajamas.

We are still in the process of creating these components, so not every Pajamas component is available as ViewComponent. Reach out to the Foundations team if the component you are looking for is not yet available.

Available components

Consider this list a best effort. The full list can be found in app/components/pajamas. Also see our Lookbook (http://gdk.test:3000/rails/lookbook) for a more interactive way to browse our components.


The Pajamas::AlertComponent follows the Pajamas Alert specification.


By default this creates a dismissible info alert with icon:

= render "Almost done!")

You can set variant, hide the icons and more:

= render "All done!",
  variant: :success,
  dismissible: :false,
  show_icon: false)

For the full list of options, see its source.

The Pajamas::BannerComponent follows the Pajamas Banner specification.


In its simplest form the banner component looks like this:

= render 'Learn more', button_link: example_path,
  svg_path: 'illustrations/example.svg') do |c|
  - c.with_title { 'Hello world!' }
  %p Content of your banner goes here...

If you have a need for more control, you can also use the illustration slot instead of svg_path and the primary_action slot instead of button_text and button_link:

= render do |c|
  - c.with_illustration do
    = custom_icon('my_inline_svg')
  - c.with_title do
    Hello world!
  - c.with_primary_action do
    = render 'my_button_in_a_partial'

For the full list of options, see its source.


The Pajamas::ButtonComponent follows the Pajamas Button specification.


The button component has a lot of options but all of them have good defaults, so the simplest button looks like this:

= render do |c|
  = _('Button text goes here')

The following example shows most of the available options:

= render :secondary,
  variant: :danger,
  size: :small,
  type: :submit,
  disabled: true,
  loading: false,
  block: true) do |c|
  Button text goes here

You can also create button-like looking <a> tags, like this:

= render root_path) do |c|
  Go home

For the full list of options, see its source.


The Pajamas::CardComponent follows the Pajamas Card specification.


The card has one mandatory body slot and optional header and footer slots:

= render do |c|
  - c.with_header do
    I'm the header.
  - c.with_body do
    %p Multiple line
    %p body content.
  - c.with_footer do
    Footer goes here.

If you want to add custom attributes to any of these or the card itself, use the following options:

= render {id: "my-id"}, body_options: {data: { count: 1 }})

header_options and footer_options are available, too.

For the full list of options, see its source.

Checkbox tag

The Pajamas::CheckboxTagComponent follows the Pajamas Checkbox specification.

The name argument and label slot are required.

For example:

= render 'project[initialize_with_sast]',
  checkbox_options: { data: { testid: 'initialize-with-sast-checkbox', track_label: track_label, track_action: 'activate_form_input', track_property: 'init_with_sast' } }) do |c|
  - c.with_label do
    = s_('ProjectsNew|Enable Static Application Security Testing (SAST)')
  - c.with_help_text do
    = s_('ProjectsNew|Analyze your source code for known security vulnerabilities.')
    = link_to _('Learn more.'), help_page_path('user/application_security/sast/index'), target: '_blank', rel: 'noopener noreferrer', data: { track_action: 'followed' }

For the full list of options, see its source.


The Pajamas::CheckboxComponent follows the Pajamas Checkbox specification.

Pajamas::CheckboxComponent is used internally by the GitLab UI form builder and requires an instance of ActionView::Helpers::FormBuilder to be passed as the form argument. It is preferred to use the gitlab_ui_checkbox_component method to render this ViewComponent. To use a checkbox without an instance of ActionView::Helpers::FormBuilder use CheckboxTagComponent.

For the full list of options, see its source.


The Pajamas::ToggleComponent follows the Pajamas Toggle specification.

= render 'js-force-push-toggle',
  label: s_("ProtectedBranch|Toggle allowed to force push"),
  is_checked: protected_branch.allow_force_push,
  label_position: :hidden) do
  Leverage this block to render a rich help text. To render a plain text help text, prefer the `help` parameter.
The toggle ViewComponent is special as it depends on the Vue.js component. To actually initialize this component, make sure to call the initToggle helper from ~/toggles.

For the full list of options, see its source.


Layout components can be used to create common layout patterns used in GitLab.

Available components

Page heading

A standard page header with a page title and optional actions.


= render'Page title')) do |c|
  - c.with_actions do
    = buttons

For the full list of options, see its source.

Horizontal section

Many of the settings pages use a layout where the title and description are on the left and the settings fields are on the right. The Layouts::HorizontalSectionComponent can be used to create this layout.


= render { class: 'gl-mb-6' }) do |c|
  - c.with_title { _('Naming, visibility') }
  - c.with_description do
    = _('Update your group name, description, avatar, and visibility.')
    = link_to _('Learn more about groups.'), help_page_path('user/group/index')
  - c.with_body do
      = f.label :name, _('New group name')
      = f.text_field :name

For the full list of options, see its source.

Best practices

  • If you are about to create a new view in Haml, use the available components over creating plain Haml tags with CSS classes.
  • If you are making changes to an existing Haml view and see, for example, a button that is still implemented with plain Haml, consider migrating it to use a ViewComponent.
  • If you decide to create a new component, consider creating previews for it, too. This will help others to discover your component with Lookbook, also it makes it much easier to test its different states.