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Preview Layouts

Lookbook uses whichever layout template has been specified in the ViewComponent config to yield rendered previews into.

If none has been specified then the default application layout will be used, as per the default ViewComponent behaviour.

It is strongly recommended to use a standalone preview layout for previews so it can be customised without the chance of affecting the main application.

To set a custom layout for all previews, use the view_component.default_preview_layout config option:

# config/application.rb
# Set the default layout to app/views/layouts/component_preview.html.erb
config.view_component.default_preview_layout = "component_preview"

See the ViewComponent docs for more info.

Example preview layout

A basic preview layout template is shown below. It uses display variables to allow the background color and and the maximum width of the wrapper to be set on a per-preview basis.

<!-- app/views/layouts/component_preview.html.erb -->
<!DOCTYPE html>
<html style="background-color: <%= params[:lookbook][:display][:bg_color] || "white" %>">
  <title>Component Preview</title>
  <meta name="viewport" content="width=device-width,initial-scale=1">
  <%= stylesheet_pack_tag 'application', media: 'all' %>
  <%= javascript_pack_tag 'application' %>
<body style="padding: 20px">
  <div style="
    margin-left: auto;
    margin-right: auto;
    max-width: <%= params[:lookbook][:display][:max_width] || "100%" %>
    <%= yield %> <!-- rendered preview will be injected here -->

Preview helpers

Lookbook includes a few helpers that are only accessible in preview templates and can be used to help clean up display param and custom data access, if desired.


Returns a display parameter value or optional fallback.

lookbook_display <name> <fallback?>
Type: Symbol
<div style="max-width: <%= lookbook_display(:max_width, "100%") %>">...</div>


Returns a custom data property property value or optional fallback.

lookbook_data <name> <fallback?>
Type: Symbol
<p>Made by <%= lookbook_data(:company_name, "Acme Widgets") %></p>