User Guide / Get Started

Upgrade Guide

For most projects upgrading from Lookbook v1.x to v2.x will not require any code updates.

However there are a small number of breaking changes in v2.0 which may need some attention. These are detailed below:

File watching & dependencies

Lookbook now uses Rails’ native file watching system to detect changes when running in development.

Because of this the listen and actioncable gems are now optional dependencies and are no longer bundled with Lookbook.

Apps that do not include these gems in their Gemfile will no longer see live updates to the Lookbook UI after changing files - a manual refresh of the page will be required.

To enable live UI updates in development, add the listen and actioncable gems to the development group (if your app does already include them elsewhere):

# Gemfile
group :development do
  gem "listen"
  gem "actioncable"

'Examples' are now 'scenarios'

Methods within preview classes are now referred to as scenarios instead of examples - both in code and in documentation.

Variables and method names have been renamed accordingly, and the use of example/examples has been deprecated and will be removed in Lookbook 3.0.

Any custom panel templates or code that uses Lookbook’s Ruby API should be updated to reflect the naming change.

Preview group rendering

The view template used to render grouped scenarios together in a single preview has moved from lookbook/preview.html.erb to lookbook/previews/group.html.erb.

Apps that have customised the rendering of preview groups by placing an amended version of this template in their views directory will need to move it to match the new path.

Panel positions

It is no longer possible to provide a position option when adding custom inspector panels.

Which inspector panels to show (and what order they should be displayed in) is now set using the preview_inspector.drawer_panels config option. Read more →

API changes

Lookbook’s ‘entity’ classes have been renamed. This is unlikely to affect users directly but is documented here for completeness:

  • Preview -> PreviewEntity
  • PreviewExample -> ScenarioEntity
  • PreviewGroup -> ScenarioGroupEntity
  • RenderedExample -> RenderedScenarioEntity
  • Page -> PageEntity
  • Component -> RenderableEntity

A number of method names have also been changed (e.g. see the note on examples/scenarios above). Aliases have been put in place with deprecation warnings where this has been done.

Rake tasks

The lookbook:previews:preparse rake task (previously deprecated as no longer required) has been removed.


The ‘workbench’ app (previously run via the bin/workbench command) has been removed to reduce the maintence overhead of managing an additional separate app within the codebase.

It’s recommended to use the Lookbook demo app set up to reference a local copy of the Lookbook gem for testing the development of new features.

User Guide

Extending Lookbook