Unpoly is an unobtrusive JavaScript framework for server-side web applications.
The unpoly-rails gem helps integrating Unpoly with Ruby on Rails applications.
This branch tracks the next major version, Unpoly 3.x.
If you're using Unpoly 2.x, use the 2.x-stable branch.
If you're using Unpoly 1.x or 0.x, use the 1.x-stable branch in the unpoly repository.
Add the following line to your Gemfile:
gem 'unpoly-rails'Now run bundle install and restart your development server.
If you're using esbuild or Webpacker, install the unpoly npm package to get Unpoly's frontend files.
Now import Unpoly from your application.js pack:
import 'unpoly/unpoly.js'
import 'unpoly/unpoly.css'You may need to import additional files, e.g. when migrating from an old Unpoly version.
If you're using the Asset Pipeline, this unpoly-rails gem also contains Unpoly's frontend files. The files are automatically added to the Asset Pipeline's search path.
Add the following line to your application.js manifest:
//= require unpolyAlso add the following line to your application.css manifest:
/*
*= require unpoly
*/You may need to require additional files, e.g. when migrating from an old Unpoly version.
This unpoly-rails gem implements the optional server protocol by providing the following helper methods to your controllers, views and helpers.
Use up? to test whether the current request is a fragment update:
up? # => true or falseTo retrieve the CSS selector that is being updated, use up.target:
up.target # => '.content'The Unpoly frontend will expect an HTML response containing an element that matches this selector. Your Rails app is free to render a smaller response that only contains HTML matching the targeted selector. You may call up.target? to test whether a given CSS selector has been targeted:
if up.target?('.sidebar')
render('expensive_sidebar_partial')
endFragment updates may target different selectors for successful (HTTP status 200 OK) and failed (status 4xx or 5xx) responses.
Use these methods to inspect the target for failed responses:
up.fail_target: The CSS selector targeted for a failed responseup.fail_target?(selector): Whether the given selector is targeted for a failed responseup.any_target?(selector): Whether the given selector is targeted for either a successful or a failed response
The server may instruct the frontend to render a different target by assigning a new CSS selector to the up.target property:
unless signed_in?
up.target = 'body'
render 'sign_in'
endThe frontend will use the server-provided target for both successful (HTTP status 200 OK) and failed (status 4xx or 5xx) responses.
Sometimes it's OK to render nothing, e.g. when you know that the current layer is to be closed.
In this case use head(:no_content):
class NotesController < ApplicationController
def create
@note = Note.new(note_params)
if @note.save
if up.layer.overlay?
up.layer.accept(@note.id)
head :no_content
else
redirect_to @note
end
end
end
endTo force Unpoly to set a document title when processing the response:
up.title = 'Title from server'This is useful when you skip rendering the <head> in an Unpoly request.
You may use up.emit to emit an event on the document after the
fragment was updated:
class UsersController < ApplicationController
def show
@user = User.find(params[:id])
up.emit('user:selected', id: @user.id)
end
endIf you wish to emit an event on the current layer
instead of the document, use up.layer.emit:
class UsersController < ApplicationController
def show
@user = User.find(params[:id])
up.layer.emit('user:selected', id: @user.id)
end
endTo test whether the current request is a form validation:
up.validate?When detecting a validation request, the server is expected to validate (but not save) the form submission and render a new copy of the form with validation errors. A typical saving action should behave like this:
class UsersController < ApplicationController
def create
user_params = params[:user].permit(:email, :password)
@user = User.new(user_params)
if up.validate?
@user.valid? # run validations, but don't save to the database
render 'form' # render form with error messages
elsif @user.save?
sign_in @user
else
render 'form', status: :bad_request
end
end
endYou may also access the names of the fields that triggered the validation request:
up.validate_names # => ['email', 'password']You may also test if a given field name is being validated:
up.validate_name?('email') # => trueWhen Unpoly reloads or polls a fragment, the server will often render the same HTML. You can configure your controller actions to only render HTML if the underlying content changed since an earlier request.
Only rendering when needed saves CPU time on your server, which spends most of its response time rendering HTML. This also reduces the bandwidth cost for a request/response exchange to ~1 KB.
When a fragment is reloaded, Unpoly sends an If-Modified-Since request header with the fragment's earlier Last-Modified time. It also sends an If-None-Match header with the fragment's earlier ETag.
Rails' conditional GET support lets you compare and set modification times and ETags with methods like #fresh_when or #stale?:
class MessagesController < ApplicationController
def index
@messages = current_user.messages.order(time: :desc)
# If the request's ETag and last modification time matches the given `@messages`,
# does not render and send a a `304 Not Modified` response.
# If the request's ETag or last modification time does not match, we will render
# the `index` view with fresh `ETag` and `Last-Modified` headers.
fresh_when(@messages)
end
endWhen your Content Security Policy disallows eval(), Unpoly cannot directly run callbacks HTML attributes. This affects [up-] attributes like [up-on-loaded] or [up-on-accepted]. See Unpoly's CSP guide for details.
The following callback would crash the fragment update with an error like Uncaught EvalError: call to Function() blocked by CSP:
link_to 'Click me', '/path, 'up-follow': true, 'up-on-loaded': "alert()"Unpoly lets your work around this by prefixing your callback with your response's CSP nonce:
link_to 'Click me', '/path', 'up-follow': true, 'up-on-loaded': 'nonce-kO52Iphm8BAVrcdGcNYjIA== alert()')To keep your callbacks compact, you may use the up.safe_callback helper for this:
link_to 'Click me', '/path, 'up-follow': true, 'up-on-loaded': up.safe_callback("alert()")For this to work you must also include the <meta name="csp-nonce"> tag in the <head> of your initial page. Rails has a csp_meta_tag helper for that purpose.
Note
Prefixing nonces only works for [up-on...] attributes. You cannot use it for native HTML attributes like [onclick].
Calling up.context will return the context object of the targeted layer.
The context is a JSON object shared between the frontend and the server. It persists for a series of Unpoly navigation, but is cleared when the user makes a full page load. Different Unpoly layers will usually have separate context objects, although layers may choose to share their context scope.
You may read and change the context object. Changes will be sent to the frontend with your response.
class GamesController < ApplicationController
def restart
up.context[:lives] = 3
render 'stage1'
end
endKeys can be accessed as either strings or symbols:
puts "You have " + up.layer.context[:lives] + " lives left"
puts "You have " + up.layer.context['lives'] + " lives left"You may delete a key from the frontend by calling up.context.delete:
up.context.delete(:foo)You may replace the entire context by calling up.context.replace:
context_from_file = JSON.parse(File.read('context.json))
up.context.replace(context_from_file)up.context is an alias for up.layer.context.
Use the methods below to interact with the layer of the fragment being targeted.
Note that fragment updates may target different layers for successful (HTTP status 200 OK) and failed (status 4xx or 5xx) responses.
Returns the mode of the targeted layer (e.g. "root" or "modal").
Returns whether the targeted layer is the root layer.
Returns whether the targeted layer is an overlay (not the root layer).
Returns the context object of the targeted layer.
See documentation for up.context, which is an alias for up.layer.context.
Accepts the current overlay.
Does nothing if the root layer is targeted.
Note that Rails expects every controller action to render or redirect.
Your action should either call up.render_nothing or respond with text/html content matching the requested target.
Dismisses the current overlay.
Does nothing if the root layer is targeted.
Note that Rails expects every controller action to render or redirect.
Your action should either call up.render_nothing or respond with text/html content matching the requested target.
Emits an event on the targeted layer.
Returns the mode of the layer targeted for a failed response.
Returns whether the layer targeted for a failed response is the root layer.
Returns whether the layer targeted for a failed response is an overlay.
Returns the context object of the layer targeted for a failed response.
The Unpoly frontend caches server responses for a few minutes, making requests to these URLs return instantly.
Only GET requests are cached. The entire cache is expired after every non-GET request (like POST or PUT).
The server may override these defaults. For instance, the server can expire Unpoly's client-side response cache, even for GET requests:
up.cache.expireYou may also expire a single URL or URL pattern:
up.cache.expire('/notes/*')You may also prevent cache expiration for an unsafe request:
up.cache.expire(false)Here is an longer example where the server uses careful cache management to avoid expiring too much of the client-side cache:
def NotesController < ApplicationController
def create
@note = Note.create!(params[:note].permit(...))
if @note.save
up.cache.expire('/notes/*') # Only expire affected entries
redirect_to(@note)
else
up.cache.expire(false) # Keep the cache fresh because we haven't saved
render 'new'
end
end
...
endInstead of expiring pages from the cache you may also evict. The difference is that expired pages can still be rendered instantly and are then revalidated with the server. Evicted pages are erased from the cache.
You may also expire all entries matching an URL pattern:
To evict the entire client-side cache:
up.cache.evictYou may also evict a single URL or URL pattern:
up.cache.evict('/notes/*')unpoly-rails patches redirect_to
so Unpoly-related request and response headers are preserved for the action you redirect to.
Accessing Unpoly-related request headers through helper methods like up.target will automatically add a Vary response header. This is to indicate that the request header influenced the response and the response should be cached separately for each request header value.
For example, a controller may access the request's X-Up-Mode through the up.layer.mode helper:
def create
# ...
if up.layer.mode == 'modal' # Sets Vary header
up.layer.accept
else
redirect_to :show
end
endunpoly-rails will automatically add a Vary header to the response:
Vary: X-Up-ModeThere are cases when reading an Unpoly request header does not necessarily influence the response, e.g. for logging. In that cases no Vary header should be set. To do so, call the helper method inside an up.no_vary block:
up.no_vary do
Rails.logger.info("Unpoly mode is " + up.layer.mode.inspect) # No Vary header is set
endNote that accessing response.headers[] directly never sets a Vary header:
Rails.logger.info("Unpoly mode is " + response.headers['X-Up-Mode']) # No Vary header is setunpoly-rails installs a before_action into all controllers which echoes the request's URL as a response header X-Up-Location and the request's
HTTP method as X-Up-Method.
unpoly-rails sets an _up_method cookie that Unpoly needs to detect the request method for the initial page load.
If the initial page was loaded with a non-GET HTTP method, Unpoly will fall back to full page loads for all actions that require pushState.
The reason for this is that some browsers remember the method of the initial page load and don't let the application change it, even with pushState. Thus, when the user reloads the page much later, an affected browser might request a POST, PUT, etc. instead of the correct method.
Unpoly lets you submit forms via AJAX by using the form[up-submit] selector or up.submit() function.
For Unpoly to be able to detect a failed form submission, the form must be re-rendered with a non-200 HTTP status code. We recommend to use either 400 (bad request) or 422 (unprocessable entity).
To do so in Rails, pass a :status option to render:
class UsersController < ApplicationController
def create
user_params = params[:user].permit(:email, :password)
@user = User.new(user_params)
if @user.save?
sign_in @user
else
render 'form', status: :bad_request
end
end
endBefore you create a pull request, please have some discussion about the proposed change by opening an issue on GitHub.
- Install the Ruby version from
.ruby-version(currently 2.3.8) - Install Bundler by running
gem install bundler - Install dependencies by running
bundle install - Run
bundle exec rspec
The tests run against a minimal Rails app that lives in spec/dummy.
Install the unpoly-rails and unpoly repositories into the same parent folder:
projects/
unpoly/
unpoly-rails/
During development unpoly-rails will use assets from the folder assets/unpoly-dev, which is symlinked against the dist folder of the ``unpoly` repo.
Before packaging the gem, a rake task will copy symlinked files assets/unpoly-dev/* to assets/unpoly/*. The latter is packaged into the gem and distributed.
projects/
unpoly/
dist/
unpoly.js
unpoly.css
unpoly-rails
assets/
unpoly-dev -> ../../unpoly/dist
unpoly.js -> ../../unpoly/dist/unpoly.js
unpoly.css -> ../../unpoly/dist/unpoly.css
unpoly
unpoly.js
unpoly.css
Making a new release of unpoly-rails involves the following steps:
- Make a new build of unpoly (
npm run build) - Make a new release of the unpoly npm package
- Bump the version in
lib/unpoly/rails/version.rbto match that in Unpoly'spackage.json - Commit and push the changes
- Run
rake gem:release