👀 Lookbook 👀

A native development UI for ViewComponent

--- **Lookbook gives [ViewComponent](http://viewcomponent.org/)-based projects a _ready-to-go_ development UI for navigating, inspecting and interacting with component previews.** It uses (and extends) the native [ViewComponent preview functionality](https://viewcomponent.org/guide/previews.html), so you don't need to learn a new DSL or create any extra files to get up and running. Lookbook uses [RDoc/Yard-style comment tags](#annotating-preview-files) to extend the capabilities of ViewComponent's previews whilst maintaining compatability with the standard preview class format, so you can add or remove Lookbook at any time without having to rework your code. ![Lookbook UI](.github/assets/lookbook_screenshot.png) ### Features - Tree-style navigation menu with live search/filter - Resizable preview window for responsive testing - Highlighted preview source code and HTML output - Auto-updating UI when component or preview files are updated _(Rails v6.0+ only)_ - Use comment tag annotations for granular customisation of the preview experience - Fully compatible with standard the ViewComponent preview system - [**Experimental**] In-browser live editable preview parameters (similar to Storybook Controls/Knobs) ## Lookbook demo If you want to have a quick play with Lookbook, the easiest way is to [give the demo app](https://github.com/allmarkedup/lookbook-demo) a spin. It's a basic Rails/ViewComponent app with a few test components included to tinker with. The [demo app repo](https://github.com/allmarkedup/lookbook-demo) contains instructions on how to get it up and running. ## Installing ### 1. Add as a dependency Add Lookbook to your `Gemfile` somewhere **after** the ViewComponent gem. For example: ```ruby gem "view_component", require: "view_component/engine" gem "lookbook" ``` ### 2. Mount the Lookbook engine You then need to mount the Lookbook engine (at a path of your choosing) in your `routes.rb` file: ```ruby Rails.application.routes.draw do if Rails.env.development? mount Lookbook::Engine, at: "/lookbook" end end ``` The `at` property determines the root URL that the Lookbook UI will be served at. > If you would like to expose the Lookbook UI in production as well as in development, just remove the `if Rails.env.development?` condition from around the mount statement. Then you can start your app as normal and navigate to `http://localhost:3000/lookbook` (or whatever mount path you specified) to view your component previews in the Lookbook UI. ## Usage You don't need to do anything special to see your ViewComponent previews and examples in Lookbook - just create them as normal and they'll automatically appear in the Lookbook UI. Preview templates, custom layouts and even bespoke [preview controllers](https://viewcomponent.org/guide/previews.html#configuring-preview-controller) should all work as you would expect. > If you are new to ViewComponent development, checkout the ViewComponent [documentation](https://viewcomponent.org/guide/) on how to get started developing your components and [creating previews](https://viewcomponent.org/guide/previews.html). ## Annotating preview files Lookbook parses [Yard-style comment tags](https://rubydoc.info/gems/yard/file/docs/Tags.md) in your preview classes to customise and extend the standard ViewComponent preview experience: ```ruby # @label Basic Button # @display bg_color #fff class ButtonComponentPreview < ViewComponent::Preview # Primary button # --------------- # This is the button style you should use for most things. # # @label Primary def default render ButtonComponent.new do "Click me" end end # Button with icon # ---------------- # This example uses dynamic preview parameters # which can be edited live in the Lookbook UI # # @param text # @param icon select [heart, cog, alert] def icon(text: "Spread the love", icon: "heart") render ButtonComponent.new(icon: icon) do text end end # Inverted button # --------------- # For light-on-dark screens # # @display bg_color #000 def secondary render ButtonComponent.new(style: :inverted) do "Click me" end end # Unicorn button # --------------- # This button style is still a **work in progress**. # # @hidden def secondary render ButtonComponent.new do "Click me" end end # @!group More examples def short_text render ButtonComponent.new do "Go" end end def long_text render ButtonComponent.new do "Click here to do this thing because it's the best way to do it" end end def emoji_text render ButtonComponent.new do "👀📗" end end # @!endgroup end ``` **Tags** are just strings identified by their `@` prefix - for example `@hidden`. Tags are always placed in a comment above the relevant preview class or example method. The following Lookbook-specific tags are available for use: * [`@label`](#label-tag) * [`@display`](#display-tag) * [`@!group ... @!endgroup`](#group-tag) * [`@hidden`](#hidden-tag) * [`@param`](#param-tag) [⚠️ **experimental!** - requires [feature opt-in](#experimental-features) ⚠️]

🏷 @label

Used to replace the auto-generated navigation label for the item with ``. ```ruby @label ``` > Available for preview classes & example methods. ```ruby # @label Preview Label class FooComponentPreview < ViewComponent::Preview # @label Example Label def default end end ```

🏷 @display

The `@display` tag lets you pass custom parameters to your preview layout so that the component preview can be customised on a per-example basis. ```ruby # @display bg_color #eee class FooComponentPreview < ViewComponent::Preview # @display max_width 500px # @display wrapper true def default end end ``` The `@display` tag can be applied at the preview (class) or at the example (method) level, and takes the following format: ```ruby @display ``` - `` must be a valid Ruby hash key name, without quotes or spaces - `` will be parsed using the [Ruby YAML parser](https://yaml.org/YAML_for_ruby.html) to resolve the value These display parameters can then be accessed via the `params` hash in your preview layout using `params[:lookbook][:display][]`: ```html Preview Layout

<% if params[:lookbook][:display][:wrapper] == true %>

<% else %> <%= yield %> <% end %>

``` > By default ViewComponent will use your default application layout for displaying the rendered example. However it's often better to create a seperate layout that you can customise and use specifically for previewing your components. See the ViewComponent [preview docs](https://viewcomponent.org/guide/previews.html) for instructions on how to set that up. Any `@display` params set at the preview (class) level with be merged with those set on individual example methods. #### Global display params Global (fallback) display params can be defined via a configuration option: ```ruby # config/application.rb config.lookbook.preview_display_params = { bg_color: "#fff", max_width: "100%" } ``` Globally defined display params will be available to all previews. Any preview or example-level `@display` values with the same name will take precedence and override a globally-set one.

🔖 `@!group ... @!endgroup`

For smaller components, it can often make sense to render a set of preview examples in a single window, rather than representing them as individual items in the navigation which can start to look a bit cluttered. You can group a set of examples by wrapping them in `@!group ` / `@!endgroup` tags within your preview file: ```ruby class HeaderComponentPreview < ViewComponent::Preview def standard render Elements::HeaderComponent.new do "Standard header" end end # @!group Sizes def small render Elements::HeaderComponent.new(size: 12) do "Small header" end end def medium render Elements::HeaderComponent.new(size: 16) do "Small header" end end def big render Elements::HeaderComponent.new(size: 24) do "Small header" end end # @!endgroup end ``` The example above would display the `Sizes` examples grouped together on a single page, rather than as indiviual items in the navigation:

You can have as many groups as you like within a single preview class, but each example can only belong to one group.

🏷 `@hidden`

Used to temporarily exclude an item from the Lookbook navigation. The item will still be accessible via it's URL. Can be useful when a component (or a variant of a component) is still in development and is not ready to be shared with the wider team. > Available for both preview classes & example methods. ```ruby # @hidden class FooComponentPreview < ViewComponent::Preview # @hidden def default end end ```

🚧 @param (experimental)

> ⚠️ This feature is currently flagged as an **experimental** feature which requires [feature opt-in](#experimental-features) to use. Its API and implementation may change in the future. The `@param` tag provides the ability to specify **editable preview parameters** which can be changed in the Lookbook UI in order to customise the rendered output on the fly, much like the [Controls (knobs) addon](https://storybook.js.org/addons/@storybook/addon-controls) for Storybook. Each `@param` will have an associated form field generated for it. The values for each field will be handled as [dynamic preview params](https://viewcomponent.org/guide/previews.html#:~:text=It%E2%80%99s%20also%20possible%20to%20set%20dynamic%20values%20from%20the%20params%20by%20setting%20them%20as%20arguments%3A) when rendering the example. The `@param` tag takes the following format: ```ruby @param ``` - `` - name of the dynamic preview param - `` - input field type to generate in the UI - `` - YAML-encoded field options, used for some field types #### Input types The following **input field types** are available for use: 📝 **Text-style inputs** - Single line fields, useful for short strings of text or numbers. ```ruby @param text @param email @param number @param url @param tel ``` > The above types only differ in the validation constraints they impose on the input field. 📝 **Textarea** - Multi-line textarea field for longer-form content. ```ruby @param textarea ``` 📝 **Select box** - Dropdown select field for selecting from a list of known options. ```ruby @param select ``` `` should be a [YAML array](https://yaml.org/YAML_for_ruby.html#simple_inline_array) of options which must be formatted in the same style as the input for Rails' [`options_for_select`](https://apidock.com/rails/v6.0.0/ActionView/Helpers/FormOptionsHelper/options_for_select) helper: ```ruby # Basic options: # @param theme select [primary, secondary, danger] # With custom labels (each item itself an array of [label, value]): # @param theme select [[Primary theme, primary], [Secondary theme, secondary], [Danger theme, danger]] # With empty option (`~` in YAML) # @param theme select [~, primary, secondary, danger] ``` > **Note**: In most cases YAML does not require quoting of strings, however if you are running into issues check out the [Ruby YAML docs](https://yaml.org/YAML_for_ruby.html) for a complete syntax reference. 📝 **Toggle** - On/off switch for toggling boolean values. ```ruby @param toggle ``` #### Default values Default values are specified as part of the preview example method parameters in the usual Ruby way: ```ruby def button(content: "Click me", theme: "primary", arrow: false) # ... end ``` These will be used as the default values for the param fields. > Note that the default values are **not** evaluated at runtime, so you cannot use method calls to generate the defaults. Only static default values are supported. #### Type casting values Most dynamic param values are passed to the example method as strings, with the following exceptions: - `toggle` input - values are cast to booleans - `number` input - values are cast to integers In some cases, you may want to type cast the parameter value to something else (for example a `Symbol`) before using it when initializing the component. To help with this, a `type` option can be specified in the `@param` definition to automatically cast the dynamic value to a different type: ```ruby # @param [] ``` In the example below, the value of the `theme` param (by default a string) will be automatically cast to a Symbol, ready for use in instantiating the component. ```ruby # @param theme [Symbol] select [primary, secondary, danger] def default(theme: :primary) render Elements::ButtonComponent.new(theme: theme) do "Click me" end end ``` The supported types to cast to are: - `String` - *default for all except `toggle` inputs* - `Boolean` - *default for `toggle` inputs* - `Symbol` - `Date` - `DateTime` - `Integer` - `Float` The following structured types are also available but should be considered **experimental** - you may run into bugs! - `Hash` - *value string converted to Hash using the Ruby YAML parser* - `Array` - *value string converted to Array using the Ruby YAML parser* #### Full example: ```ruby class ButtonComponentPreview < ViewComponent::Preview # The params defined below will be editable in the UI: # # @param content text # @param theme select [primary, secondary, danger] # @param arrow toggle def default(content: "Click me", theme: "primary", arrow: true) render Elements::ButtonComponent.new(theme: theme, arrow: arrow) do content end end end ```

### Adding notes All comment text other than tags will be treated as markdown and rendered in the **Notes** panel for that example in the Lookbook UI. ```ruby # @hidden class ProfileCardComponentPreview < ViewComponent::Preview # Profile Card # ------------ # Use the default profile card component whenever you need to represent a user. def default end end ```

## Configuration Lookbook will use the ViewComponent [configuration](https://viewcomponent.org/api.html#configuration) for your project to find and render your previews so you generally you won't need to configure anything separately. However the following Lookbook-specific config options are also available: ### UI auto-refresh > ⚠️ UI auto-refresh is only supported in Rails v6.0+ Disable/enable the auto-updating of the Lookbook UI when files change. Enabled by default. ```ruby config.lookbook.auto_refresh = false # default is true ``` By default Lookbook will listen for changes in any [preview directories](https://viewcomponent.org/api.html#preview_paths) as well as in the [components directory](config.view_component.preview_paths) itself. If you wish to add additional paths to listen for changes in, you can use the `listen_paths` option: ```ruby config.lookbook.listen_paths << Rails.root.join('app/other/directory') ```

Experimental features opt-in

Some features may occasionally be released behind a 'experimental' feature flag while they are being tested and refined, to allow people to try them out and provide feedback. > ⚠️ **Please note:** Experimental features should be considered to be **subject to extensive change** and breaking changes to them may be made within point releases - these features are **not** considered to be covered by [semver](https://semver.org/) whilst flagged as 'experimental'. ⚠️ #### Opting into specific features (recommended) To opt into individual experimental features, include the name of the feature in the `experimental_features` config option: ```ruby config.lookbook.experimental_features = ["feature_name"] ``` The current experimental features that can be opted into are: - `params`: Live-editable, dynamic preview parameters ([read more](#param-tag)). Include `"params"` in the `experimental_features` config option to opt in. #### Opting into all experimental features (not recommended!) If you want to live life on the bleeding-edge you can opt-in to all current **and future** experimental features (usual caveats apply): ```ruby config.lookbook.experimental_features = true ``` ## Keyboard shortcuts Lookbook provides a few keyboard shortcuts to help you quickly move around the UI. - `f` - move focus to the nav filter box - `Esc` [when focus is in nav filter box] - Clear contents if text is present, or return focus to the UI if the box is already empty - `s` - Switch to Source tab in the inspector - `o` - Switch to Output tab in the inspector - `n` - Switch to Notes tab in the inspector - `r` - Refresh the preview (useful if using something like Faker to generate randomised data for the preview) - `w` - Open the standalone rendered preview in a new window ## Troubleshooting #### Blank preview window Certain setups (for example when using `Rack::LiveReload`) can cause an issue with the way that the preview iframe displays the rendered component preview (i.e. using the `srcdoc` attribute to avoid extra requests). If you are seeing a blank preview window, but the source and output tabs are both displaying code as expected, you can disable the use of the `srcdoc` attribute using the following configuration option: ```ruby config.lookbook.preview_srcdoc = false ``` ## Contributing Lookbook is very much a small hobby/side project at the moment. I'd love to hear from anyone who is interested in contributing but I'm terrible at replying to emails or messages, so don't be surprised if I take forever to get back to you. It's not personal 😜 ### Developing on a local version of Lookbook The quickest way to get a development version of Lookbook up and running is to use the [lookbook-demo](https://github.com/allmarkedup/lookbook-demo) app and link it to a local version of the Lookbook gem: #### Initial setup: 1. Clone this repository somewhere on your machine - `git clone git@github.com:allmarkedup/lookbook.git` 2. Also pull down the [lookbook-demo](https://github.com/allmarkedup/lookbook-demo) repository to your machine 3. In the `Gemfile` of the `lookbook-demo` repository, replace `gem "lookbook", '>= 0.1', git: "https://github.com/allmarkedup/lookbook", branch: "main"` with `gem "lookbook", path: "../path/to/lookbook"` (use the path to your local copy of lookbook) 4. Install dependencies - from the root of the parent project run `bundle install` #### Starting development 1. From within the `lookbook` root directory run the comand `npm run dev` (this will make sure the CSS/JS is recompiled if/when you make changes to the UI) 2. From within the `lookbook-demo` root directory run `npm run start` - this will start a server and build the demo assets Point your browser to http://localhost:3000/lookbook to see the UI. You can then make and test changes to the Lookbook code in your local copy of lookbook repo. PRs are welcome if you add anything useful :-) > Note that changes to files in the Lookbook `lib/` directory will require a server restart in order to have them applied. #### Tests You can run the tests from within the `lookbook` root directory with the `rake test` command. ## License The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).