Class: Primer::Alpha::SelectPanel

Inherits:
Component
  • Object
show all
Defined in:
app/components/primer/alpha/select_panel.rb

Overview

Select panels allow for selecting from a large number of options and can be thought of as a more capable version of the traditional HTML ‘<select>` element.

Select panels:

  1. feature an input field at the top that allows an end user to filter the list of results.

  2. can render their items statically or dynamically by fetching results from the server.

  3. allow selecting a single item or multiple items.

  4. permit leading visuals like Octicons, avatars, and custom SVGs.

  5. can be used as form inputs in Rails forms.

## Static list items

The Rails SelectPanel component allows items to be provided statically or loaded dynamically from the server. Providing items statically is done using a fetch strategy of :local in combination with the item slot:

“‘erb <%= render(Primer::Alpha::SelectPanel.new(fetch_strategy: :local))) do |panel| %>

<% panel.with_show_button { "Select item" } %>
<% panel.with_item(label: "Item 1") %>
<% panel.with_item(label: "Item 2") %>

<% end %> “‘

## Dynamic list items

List items can also be fetched dynamically from the server and will require creating a Rails controller action to respond with the list of items in addition to rendering the SelectPanel instance. Render the instance as normal, providing your desired [fetch strategy](#fetch-strategies):

“‘erb <%= render(

Primer::Alpha::SelectPanel.new(
  fetch_strategy: :remote,
  src: search_items_path  # perhaps a Rails URL helper
)

) %> “‘

Define a controller action to serve the list of items. The SelectPanel component passes any filter text in the q= URL parameter.

“‘ruby class SearchItemsController < ApplicationController

def show
  # NOTE: params[:q] may be nil since there is no filter string available
  # when the panel is first opened
  @results = SomeModel.search(params[:q] || "")
end

end “‘

Responses must be HTML fragments, eg. have a content type of ‘text/html+fragment`. This content type isn’t available by default in Rails, so you may have to register it eg. in an initializer:

“‘ruby Mime::Type.register(“text/fragment+html”, :html_fragment) “`

Render a Primer::Alpha::SelectPanel::ItemList in the action’s template, search_items/show.html_fragment.erb:

“‘erb <%= render(Primer::Alpha::SelectPanel::ItemList.new) do |list| %>

<% @results.each do |result| %>
  <% list.with_item(label: result.title) do |item| %>
    <% item.with_description(result.description) %>
  <% end %>
<% end %>

<% end %> “‘

### Selection consistency

The SelectPanel component automatically “remembers” which items have been selected across item fetch requests, meaning the controller that renders dynamic list items does not (and should not) remember these selections or persist them until the user has confirmed them, either by submitting the form or otherwise indicating completion. The SelectPanel component does not include unconfirmed selection data in requests.

## Fetch strategies

The list of items can be fetched from a remote URL, or provided as a static list, configured using the fetch_strategy attribute. Fetch strategies are summarized below.

  1. :remote: a query is made to the URL in the src attribute every time the input field changes.

  2. :eventually_local: a query is made to the URL in the src attribute when the panel is first opened. The

    results are "remembered" and filtered in-memory for all subsequent filter operations, i.e. when the input
field changes.

  3. :local: the list of items is provided statically ahead of time and filtered in-memory. No requests are made

    to the server.

## Customizing filter behavior

If the fetch strategy is :remote, then filtering is handled server-side. The server should render a Primer::Alpha::SelectPanel::ItemList (an alias of <%= link_to_component(Primer::Alpha::ActionList) %>) in the response containing the filtered list of items. The component achieves remote fetching via the [remote-input-element](github.com/github/remote-input-element), which sends a request to the server with the filter string in the q= parameter. Responses must be HTML fragments, eg. have a content type of ‘text/html+fragment`.

### Local filtering

If the fetch strategy is :local or :eventually_local, filtering is performed client-side. Filter behavior can be customized in JavaScript by setting the filterFn attribute on the instance of SelectPanelElement, eg:

“‘javascript document.querySelector(“select-panel”).filterFn = (item: HTMLElement, query: string): boolean => 

// return true if the item should be displayed, false otherwise

“‘

The element’s default filter function uses the value of the data-filter-string attribute, falling back to the element’s innerText property. It performs a case-insensitive substring match against the filter string.

### ‘SelectPanel`s as form inputs

‘SelectPanel`s can be used as form inputs. They behave very similarly to how HTML `<select>` boxes behave, and play nicely with Rails’ built-in form mechanisms. Pass arguments via the form_arguments: argument, including the Rails form builder object and the name of the field. Each list item must also have a value specified in ‘content_arguments: { data: { value: } }`.

“‘erb <% form_with(model: Address.new) do |f| %>

<%= render(Primer::Alpha::SelectPanel.new(form_arguments: { builder: f, name: "country" })) do |menu| %>
  <% countries.each do |country|
    <% menu.with_item(label: country.name, content_arguments: { data: { value: country.code } }) %>
  <% end %>
<% end %>

<% end %> “‘

The value of the ‘data: { value: … }` argument is sent to the server on submit, keyed using the name provided above (eg. `“country”`). If no value is provided for an item, the value of that item is the item’s label. Here’s the corresponding AddressesController that might be written to handle the form above:

“‘ruby class AddressesController < ApplicationController

def create
  puts "You chose #{address_params[:country]} as your country"
end

private

def address_params
  params.require(:address).permit(:country)
end

end “‘

If items are provided dynamically, things become a bit more complicated. The form_for or form_with method call happens in the view that renders the SelectPanel, which means the form builder object but isn’t available in the view that renders the list items. In such a case, it can be useful to create an instance of the form builder maually:

“‘erb <% builder = ActionView::Helpers::FormBuilder.new(

"address",  # the name of the model, used to wrap input names, eg 'address[country_code]'
nil,        # object (eg. the Address instance, which we can omit)
self,       # template
{}          # options

) %> <%= render(Primer::Alpha::SelectPanel::ItemList.new(

form_arguments: { builder: builder, name: "country" }

)) do |list| %>

<% countries.each do |country| %>
  <% menu.with_item(label: country.name, data: { value: country.code }) %>
<% end %>

<% end %> “‘

### JavaScript API

‘SelectPanel`s render a `<select-panel>` custom element that exposes behavior to the client.

#### Utility methods

  • ‘show()`: Manually open the panel. Under normal circumstances, a show button is used to show the panel, but this method exists to support unusual use-cases.

  • ‘hide()`: Manually hides (closes) the panel.

#### Query methods

  • ‘getItemById(itemId: string): Element`: Returns the item’s HTML ‘<li>` element. The return value can be passed as the item argument to the other methods listed below.

  • ‘isItemChecked(item: Element): boolean`: Returns true if the item is checked, false otherwise.

  • ‘isItemHidden(item: Element): boolean`: Returns true if the item is hidden, false otherwise.

  • ‘isItemDisabled(item: Element): boolean`: Returns true if the item is disabled, false otherwise.

NOTE: Item IDs are special values provided by the user that are attached to SelectPanel list items as the data-item-id HTML attribute. Item IDs can be provided by passing an item_id: attribute when adding items to the panel, eg:

“‘erb <%= render(Primer::Alpha::SelectPanel.new) do |panel| %>

<% panel.with_item(item_id: "my-id") %>

<% end %> “‘

The same is true when rendering ‘ItemList`s:

“‘erb <%= render(Primer::Alpha::SelectPanel::ItemList.new) do |list| %>

<% list.with_item(item_id: "my-id") %>

<% end %> “‘

#### State methods

  • ‘enableItem(item: Element)`: Enables the item, i.e. makes it clickable by the mouse and keyboard.

  • ‘disableItem(item: Element)`: Disables the item, i.e. makes it unclickable by the mouse and keyboard.

  • ‘checkItem(item: Element)`: Checks the item. Only has an effect in single- and multi-select modes.

  • ‘uncheckItem(item: Element)`: Unchecks the item. Only has an effect in multi-select mode, since items cannot be unchecked in single-select mode.

#### Events

|Name |Type |Bubbles |Cancelable | |:——————–|:——————————————|:——-|:———-| |itemActivated |‘CustomEvent<ItemActivatedEvent>` |Yes |No | |beforeItemActivated|`CustomEvent<ItemActivatedEvent>` |Yes |Yes | |dialog:open |`CustomEvent<HTMLDialogElement>` |No |No | |panelClosed |`CustomEvent<SelectPanelElement>` |Yes |No |

_Item activation_

The ‘<select-panel>` element fires an itemActivated event whenever an item is activated (eg. clicked) via the mouse or keyboard.

“‘typescript document.querySelector(“select-panel”).addEventListener(

"itemActivated",
(event: CustomEvent<ItemActivatedEvent>) => {
  event.detail.item     // Element: the <li> item that was activated
  event.detail.checked  // boolean: whether or not the result of the activation checked the item
}

) “‘

The beforeItemActivated event fires before an item is activated. Canceling this event will prevent the item from being activated.

“‘typescript document.querySelector(“select-panel”).addEventListener(

"beforeItemActivated",
(event: CustomEvent<ItemActivatedEvent>) => {
  event.detail.item      // Element: the <li> item that was activated
  event.detail.checked   // boolean: whether or not the result of the activation checked the item
  event.preventDefault() // Cancel the event to prevent activation (eg. checking/unchecking)
}

) “‘

Constant Summary collapse

ItemList =

The component that should be used to render the list of items in the body of a SelectPanel.

Primer::Alpha::ActionList
DEFAULT_PRELOAD = 
false
DEFAULT_FETCH_STRATEGY = 
:remote
FETCH_STRATEGIES = 
[
  DEFAULT_FETCH_STRATEGY,
  :eventually_local,
  :local
]
DEFAULT_SELECT_VARIANT = 
:single
SELECT_VARIANT_OPTIONS = 
[
  DEFAULT_SELECT_VARIANT,
  :multiple,
  :none,
].freeze

Constants inherited from Component

Component::INVALID_ARIA_LABEL_TAGS

Constants included from Status::Dsl

Status::Dsl::STATUSES

Constants included from ViewHelper

ViewHelper::HELPERS

Constants included from TestSelectorHelper

TestSelectorHelper::TEST_SELECTOR_TAG

Constants included from FetchOrFallbackHelper

FetchOrFallbackHelper::InvalidValueError

Constants included from Primer::AttributesHelper

Primer::AttributesHelper::PLURAL_ARIA_ATTRIBUTES, Primer::AttributesHelper::PLURAL_DATA_ATTRIBUTES

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Component

deprecated?, generate_id

Methods included from JoinStyleArgumentsHelper

#join_style_arguments

Methods included from TestSelectorHelper

#add_test_selector

Methods included from FetchOrFallbackHelper

#fetch_or_fallback, #fetch_or_fallback_boolean, #silence_deprecations?

Methods included from ClassNameHelper

#class_names

Methods included from Primer::AttributesHelper

#aria, #data, #merge_aria, #merge_data, #merge_prefixed_attribute_hashes

Methods included from ExperimentalSlotHelpers

included

Methods included from ExperimentalRenderHelpers

included

Constructor Details

#initialize(src: nil, title: "Menu", id: self.class.generate_id, size: :small, select_variant: DEFAULT_SELECT_VARIANT, fetch_strategy: DEFAULT_FETCH_STRATEGY, no_results_label: "No results found", preload: DEFAULT_PRELOAD, dynamic_label: false, dynamic_label_prefix: nil, dynamic_aria_label_prefix: nil, body_id: nil, list_arguments: {}, form_arguments: {}, show_filter: true, open_on_load: false, anchor_align: Primer::Alpha::Overlay::DEFAULT_ANCHOR_ALIGN, anchor_side: Primer::Alpha::Overlay::DEFAULT_ANCHOR_SIDE, **system_arguments) ⇒ SelectPanel

Returns a new instance of SelectPanel.

Parameters:

  • src (String) (defaults to: nil) —

    The URL to fetch search results from.

  • title (String) (defaults to: "Menu") —

    The title that appears at the top of the panel.

  • id (String) (defaults to: self.class.generate_id) —

    The unique ID of the panel.

  • size (Symbol) (defaults to: :small) —

    The size of the panel. <%= one_of(Primer::Alpha::Overlay::SIZE_OPTIONS) %>

  • select_variant (Symbol) (defaults to: DEFAULT_SELECT_VARIANT) —

    <%= one_of(Primer::Alpha::ActionList::SELECT_VARIANT_OPTIONS) %>

  • fetch_strategy (Symbol) (defaults to: DEFAULT_FETCH_STRATEGY) —

    <%= one_of(Primer::Alpha::SelectPanel::FETCH_STRATEGIES) %>

  • no_results_label (String) (defaults to: "No results found") —

    The label to display when no results are found.

  • preload (Boolean) (defaults to: DEFAULT_PRELOAD) —

    Whether to preload search results when the page loads. If this option is false, results are loaded when the panel is opened.

  • dynamic_label (Boolean) (defaults to: false) —

    Whether or not to display the text of the currently selected item in the show button.

  • dynamic_label_prefix (String) (defaults to: nil) —

    If provided, the prefix is prepended to the dynamic label and displayed in the show button.

  • dynamic_aria_label_prefix (String) (defaults to: nil) —

    If provided, the prefix is prepended to the dynamic label and set as the value of the aria-label attribute on the show button.

  • body_id (String) (defaults to: nil) —

    The unique ID of the panel body. If not provided, the body ID will be set to the panel ID with a “-body” suffix.

  • list_arguments (Hash) (defaults to: {}) —

    Arguments to pass to the underlying <%= link_to_component(Primer::Alpha::ActionList) %> component. Only has an effect for the local fetch strategy.

  • form_arguments (Hash) (defaults to: {}) —

    Form arguments to pass to the underlying <%= link_to_component(Primer::Alpha::ActionList) %> component. Only has an effect for the local fetch strategy.

  • show_filter (Boolean) (defaults to: true) —

    Whether or not to show the filter input.

  • open_on_load (Boolean) (defaults to: false) —

    Open the panel when the page loads.

  • anchor_align (Symbol) (defaults to: Primer::Alpha::Overlay::DEFAULT_ANCHOR_ALIGN) —

    The anchor alignment of the Overlay. <%= one_of(Primer::Alpha::Overlay::ANCHOR_ALIGN_OPTIONS) %>

  • anchor_side (Symbol) (defaults to: Primer::Alpha::Overlay::DEFAULT_ANCHOR_SIDE) —

    The side to anchor the Overlay to. <%= one_of(Primer::Alpha::Overlay::ANCHOR_SIDE_OPTIONS) %>



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# File 'app/components/primer/alpha/select_panel.rb', line 331

def initialize(
  src: nil,
  title: "Menu",
  id: self.class.generate_id,
  size: :small,
  select_variant: DEFAULT_SELECT_VARIANT,
  fetch_strategy: DEFAULT_FETCH_STRATEGY,
  no_results_label: "No results found",
  preload: DEFAULT_PRELOAD,
  dynamic_label: false,
  dynamic_label_prefix: nil,
  dynamic_aria_label_prefix: nil,
  body_id: nil,
  list_arguments: {},
  form_arguments: {},
  show_filter: true,
  open_on_load: false,
  anchor_align: Primer::Alpha::Overlay::DEFAULT_ANCHOR_ALIGN,
  anchor_side: Primer::Alpha::Overlay::DEFAULT_ANCHOR_SIDE,
  **system_arguments
)
  if src.present?
    url = URI(src)
    query = url.query || ""
    url.query = query.split("&").push("experimental=1").join("&")
    @src = url
  end

  @panel_id = id
  @body_id = body_id || "#{@panel_id}-body"
  @preload = fetch_or_fallback_boolean(preload, DEFAULT_PRELOAD)
  @select_variant = fetch_or_fallback(SELECT_VARIANT_OPTIONS, select_variant, DEFAULT_SELECT_VARIANT)
  @fetch_strategy = fetch_or_fallback(FETCH_STRATEGIES, fetch_strategy, DEFAULT_FETCH_STRATEGY)
  @no_results_label = no_results_label
  @show_filter = show_filter
  @dynamic_label = dynamic_label
  @dynamic_label_prefix = dynamic_label_prefix
  @dynamic_aria_label_prefix = dynamic_aria_label_prefix

  @system_arguments = deny_tag_argument(**system_arguments)
  @system_arguments[:id] = @panel_id
  @system_arguments[:"anchor-align"] = fetch_or_fallback(Primer::Alpha::Overlay::ANCHOR_ALIGN_OPTIONS, anchor_align, Primer::Alpha::Overlay::DEFAULT_ANCHOR_ALIGN)
  @system_arguments[:"anchor-side"] = Primer::Alpha::Overlay::ANCHOR_SIDE_MAPPINGS[fetch_or_fallback(Primer::Alpha::Overlay::ANCHOR_SIDE_OPTIONS, anchor_side, Primer::Alpha::Overlay::DEFAULT_ANCHOR_SIDE)]

  @title = title
  @system_arguments[:tag] = :"select-panel"
  @system_arguments[:preload] = true if @src.present? && preload?

  @system_arguments[:data] = merge_data(
    system_arguments, {
      data: { select_variant: @select_variant, fetch_strategy: @fetch_strategy, open_on_load: open_on_load }.tap do |data|
        data[:dynamic_label] = dynamic_label if dynamic_label
        data[:dynamic_label_prefix] = dynamic_label_prefix if dynamic_label_prefix.present?
        data[:dynamic_aria_label_prefix] = dynamic_aria_label_prefix if dynamic_aria_label_prefix.present?
      end
    }
  )

  @dialog = Primer::BaseComponent.new(
    id: "#{@panel_id}-dialog",
    tag: :dialog,
    data: { target: "select-panel.dialog" },
    classes: class_names(
      "Overlay",
      "Overlay-whenNarrow",
      Primer::Alpha::Dialog::SIZE_MAPPINGS[
        fetch_or_fallback(Primer::Alpha::Dialog::SIZE_OPTIONS, size, Primer::Alpha::Dialog::DEFAULT_SIZE)
      ],
    ),
    style: "position: absolute;",
  )

  @list = Primer::Alpha::SelectPanel::ItemList.new(
    **list_arguments,
    form_arguments: form_arguments,
    id: "#{@panel_id}-list",
    select_variant: @select_variant,
    role: "listbox",
    aria_selection_variant: @select_variant == :multiple ? :checked : :selected,
    aria: {
      label: "#{title} options"
    },
    p: 2
  )
end

Instance Attribute Details

#body_id ⇒ String (readonly)

The unique ID of the panel body.

Returns:

  • (String) 


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# File 'app/components/primer/alpha/select_panel.rb', line 287

def body_id
  @body_id
end

#fetch_strategy ⇒ Symbol (readonly)

<%= one_of(Primer::Alpha::SelectPanel::FETCH_STRATEGIES) %>

Returns:

  • (Symbol) 


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# File 'app/components/primer/alpha/select_panel.rb', line 297

def fetch_strategy
  @fetch_strategy
end

#panel_id ⇒ String (readonly)

The unique ID of the panel.

Returns:

  • (String) 


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# File 'app/components/primer/alpha/select_panel.rb', line 282

def panel_id
  @panel_id
end

#preload ⇒ Boolean (readonly) Also known as: preload?

Whether to preload search results when the page loads. If this option is false, results are loaded when the panel is opened.

Returns:

  • (Boolean) 


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# File 'app/components/primer/alpha/select_panel.rb', line 302

def preload
  @preload
end

#select_variant ⇒ Symbol (readonly)

<%= one_of(Primer::Alpha::ActionMenu::SELECT_VARIANT_OPTIONS) %>

Returns:

  • (Symbol) 


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# File 'app/components/primer/alpha/select_panel.rb', line 292

def select_variant
  @select_variant
end

#show_filter ⇒ Boolean (readonly) Also known as: show_filter?

Whether or not to show the filter input.

Returns:

  • (Boolean) 


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# File 'app/components/primer/alpha/select_panel.rb', line 309

def show_filter
  @show_filter
end

#src ⇒ String (readonly)

The URL to fetch search results from.

Returns:

  • (String) 


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# File 'app/components/primer/alpha/select_panel.rb', line 277

def src
  @src
end

Instance Method Details

#with_avatar_item ⇒ Object

Parameters:

  • system_arguments (Hash) —

    The arguments accepted by <%= link_to_component(Primer::Alpha::ActionList) %>‘s item slot.



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# File 'app/components/primer/alpha/select_panel.rb', line 10

def with_avatar_item
end

#with_item(**system_arguments) ⇒ Object

Adds an item to the list. Note that this method only has an effect for the local fetch strategy.

Parameters:

  • system_arguments (Hash) —

    The arguments accepted by <%= link_to_component(Primer::Alpha::ActionList) %>‘s item slot.



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# File 'app/components/primer/alpha/select_panel.rb', line 4

def with_item(**system_arguments)
end