[2.0.3] Source usability : better interfaces for sources relying on child plugins

I am not sure about the naming...

Proposal inspired from [ObjectWithPluginCollectionInterface](https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Plugin%21...) but not identical because we have a single collection and not many collections:

interface SourceWithCollectionInterface {

  /**
   * Get collection of items.
   *
   * @return array
   *   Array of items definitions.
   */
  public function getCollection(): array;

  /**
   * Get the minimal source configuration for an item.
   *
   * @param string $item_id
   *   An item ID.
   *
   * @return array
   *   A source configuration.
   */
  public function getSourceConfiguration(string $item_id): array;

  /**
   * Get the currently select item from the collection.
   *
   * @return string|null
   *   The item ID.
   */
  public function getSelectedItem(): ?string;

Do we also need a getItemLabel(string $item_id): string ?

getMinimalConfiguration does not need any parameter, unless it is static, which could be a nice idea after all.

i don’t like collection, because it reminds of the plugin collections in drupal which are managed differently…

also, the term configuration for the source refers to the global configuration, whereas we wanted the settings, i would keep settings to avoid confusion

getMinimalConfiguration does not need any parameter, unless it is static, which could be a nice idea after all.

Oops, a copy paste mistake, I fix it in my comment

• getChildPluginDefinitions >> getItems
• getSettingsSourceWithChildPlugin >> getMinimalSetting
• getChildPluginId >>getSelectedItem

interface SourceWithItemsInterface {

  /**
   * Get items.
   *
   * @return array
   *   Associative array of items definitions with ID as the key.
   */
  public function getItems(): array;

  /**
   * Get the minimal settings for an item.
   *
   * @param string $item_id
   *   An item ID.
   *
   * @return array
   *   A source setting.
   */
  public function getMinimalSetting(string $item_id): array;

  /**
   * Get the currently select item.
   *
   * @return string|null
   *   The item ID.
   */
  public function getSelectedItem(): ?string;

Is it better?

Also:

• Do we also need a getItemLabel(string $item_id): string ?
• it may be good to move ::getMinimalSetting() to SourceInterface and to implemtn it in SourcePluginBase as a proxy to PluginSettingsInterface::defaultSettings(). What do you think?

i am not so fan of items neither :)

Too late for 2.0.X

UI Patterns 2 sources where we want to extract multiple item.

Reminder: Only for slots source.

Nice to have

ComponentSource with bootstrap:card:

source_id: component
source:
  component: 
    component_id: bootstrap:card

BlockSource with system_menu_block:admin:

source_id: block
source:
  plugin_id: system_menu_block:admin

Expected in the scope of this issue

Entity Field with field:node:article:title:

  source_id: entity_field
  source:
    derivable_context: 'field:node:article:title'
    'field:node:article:title':
      value: {}

Entity Reference with entity_reference:node:article:uid:user:user:

  source_id: entity_reference
  source:
    derivable_context: 'entity_reference:node:article:uid:user:user'
    'entity_reference:node:article:uid:user:user':
      value: {}

Out of scope

Because single item:

• WysiwygWidget
• TokenSource
• ViewRowsSource

Multiple items context never reached from the top of a component data tree:

• ViewFieldSource
• FieldFormatterSourceDeriver

Thanks for your ongoing work.

It would be nice to also implement this interface on ComponentSource so it will be possible to get the same simplification in display_builder's ComponentLibraryPanel.

Also, we may need to add some properties in ::getChoices() along side label and provider: like the original plugin ID and the group/category.

It would be even better to return an object implementing standard interfaces instead of a loose array:

• PluginDefinitionInterface::getClass
• PluginDefinitionInterface::getProvider
• PluginDefinitionInterface::id
• PluginDefinitionInterface::setClass
• Unfortunately, I have found nothing for label and group/category

Can you also add this to EntityReferencedSource or DerivableContextSourceBase ?

+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary(): array {
+    $derivable_context = explode(':', $this->getSetting("derivable_context") ?? '');
+    return [
+      $derivable_context[array_key_last($derivable_context)],
+    ];
+  }

just_like_good_vibes → closed merge request !353

just_like_good_vibes → changed the visibility of the branch 3513568-2.0.3-source-usability to hidden.

here we are, ready for review :

- we have a new interface for those sources with a choice. It allows them to expose those choices to the outside world.
- we have improved the returned label of sources, in those particular cases of sources with choice.