Multiple breadcrumb parent fields

modules/islandora_breadcrumbs/config/install/islandora_breadcrumbs.breadcrumbs.yml

@@ -1,6 +1,7 @@
 maxDepth: -1
 includeSelf: FALSE
-referenceField: field_member_of
+referenceFields: 
+  - field_member_of
 dependencies:
   module:
     - islandora

modules/islandora_breadcrumbs/config/schema/islandora_breadcrumbs.schema.yml

@@ -7,6 +7,9 @@ islandora_breadcrumbs.breadcrumbs:
     includeSelf:
       type: boolean
       label: 'Include Self'
-    referenceField:
-      type: string
-      label: 'Reference Field'
+    referenceFields:
+      type: sequence
+      label: 'Reference Fields'
+      sequence:
+        type: string
+        label: 'Reference Field'

modules/islandora_breadcrumbs/islandora_breadcrumbs.install

@@ -0,0 +1,18 @@
+<?php
+
+/**
+ * @file
+ * Install/update hook implementations.
+ */
+
+/**
+ * Update referenceField config to referenceFields.
+ */
+function islandora_breadcrumbs_update_8001() {
+  $config_factory = \Drupal::configFactory();
+  $config = $config_factory->getEditable('islandora_breadcrumbs.breadcrumbs');
+  $config->set('referenceFields', [$config->get('referenceField')]);
+  $config->clear('referenceField');
+  $config->save();
+  return "Updated referenceFields config.";
+}

modules/islandora_breadcrumbs/islandora_breadcrumbs.links.menu.yml

@@ -0,0 +1,5 @@
+system.islandora_breadcrumbs_settings:
+  title: 'Breadcrumbs Settings'
+  parent: system.admin_config_islandora
+  route_name: system.islandora_breadcrumbs_settings
+  description: 'Configure Islandora breadcrumb settings'

modules/islandora_breadcrumbs/islandora_breadcrumbs.routing.yml

@@ -0,0 +1,7 @@
+system.islandora_breadcrumbs_settings:
+  path: '/admin/config/islandora/breadcrumbs'
+  defaults:
+    _form: 'Drupal\islandora_breadcrumbs\Form\IslandoraBreadcrumbsSettingsForm'
+    _title: 'Islandora Breadcrumbs Settings'
+  requirements:
+    _permission: 'administer site configuration'

modules/islandora_breadcrumbs/src/Form/IslandoraBreadcrumbsSettingsForm.php

@@ -0,0 +1,132 @@
+<?php
+
+namespace Drupal\islandora_breadcrumbs\Form;
+
+use Drupal\Core\Form\ConfigFormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Configure islandora_breadcrumbs settings.
+ */
+class IslandoraBreadcrumbsSettingsForm extends ConfigFormBase {
+
+  /**
+   * Config settings.
+   *
+   * @var string
+   */
+  const SETTINGS = 'islandora_breadcrumbs.breadcrumbs';
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'islandora_breadcrumbs_settings';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEditableConfigNames() {
+    return [
+      static::SETTINGS,
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+
+    $config = $this->config(static::SETTINGS);
+
+    $form['maxDepth'] = [
+      '#type' => 'number',
+      '#default_value' => $config->get('maxDepth'),
+      '#min' => -1,
+      '#step' => 1,
+      '#title' => $this->t('Maximum number of ancestor breadcrumbs'),
+      '#description' => $this->t("Stops adding ancestor references when the chain reaches this number. The count does not include the current node when enabled. The default value, '-1' disables this feature."),
+    ];
+
+    $form['includeSelf'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Include the current node in the breadcrumbs?'),
+      '#default_value' => $config->get('includeSelf'),
+    ];
+
+    // Using the textarea instead of a select so the site maintainer can
+    // provide an ordered list of items rather than simply selecting from a
+    // list which enforces it's own order.
+    $form['referenceFields'] = [
+      '#type' => 'textarea',
+      '#title' => $this->t('Entity Reference fields to follow'),
+      '#default_value' => implode("\n", $config->get('referenceFields')),
+      '#description' => $this->t("Entity Reference field machine names to follow when building the breadcrumbs.<br>One per line.<br>Valid options: @options",
+        [
+          "@options" => implode(", ", static::getNodeEntityReferenceFields()),
+        ]
+      ),
+      '#element_validate' => [[get_class($this), 'validateReferenceFields']],
+
+    ];
+
+    return parent::buildForm($form, $form_state);
+  }
+
+  /**
+   * Returns a list of node entity reference field machine names.
+   *
+   * We use this for building the form field description and for
+   * validating the reference fields value.
+   */
+  protected static function getNodeEntityReferenceFields() {
+    return array_keys(\Drupal::service('entity_field.manager')->getFieldMapByFieldType('entity_reference')['node']);
+  }
+
+  /**
+   * Turns a text area into an array of values.
+   *
+   * Used for validating the field reference text area
+   * and saving the form state.
+   */
+  protected static function textToArray($string) {
+    return array_filter(array_map('trim', explode("\n", $string)), 'strlen');
+  }
+
+  /**
+   * Callback for settings form.
+   *
+   * @param array $element
+   *   An associative array containing the properties and children of the
+   *   generic form element.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form for the form this element belongs to.
+   *
+   * @see \Drupal\Core\Render\Element\FormElement::processPattern()
+   */
+  public static function validateReferenceFields(array $element, FormStateInterface $form_state) {
+
+    $valid_fields = static::getNodeEntityReferenceFields();
+
+    foreach (static::textToArray($element['#value']) as $value) {
+      if (!in_array($value, $valid_fields)) {
+        $form_state->setError($element, t('"@field" is not a valid entity reference field!', ["@field" => $value]));
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $this->configFactory->getEditable(static::SETTINGS)
+      ->set('referenceFields', static::textToArray($form_state->getValue('referenceFields')))
+      ->set('maxDepth', $form_state->getValue('maxDepth'))
+      ->set('includeSelf', $form_state->getValue('includeSelf'))
+      ->save();
+
+    parent::submitForm($form, $form_state);
+  }
+
+}

modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php

@@ -64,7 +64,14 @@ public function applies(RouteMatchInterface $attributes) {
     $nid = $attributes->getRawParameters()->get('node');
     if (!empty($nid)) {
       $node = $this->nodeStorage->load($nid);
-      return (!empty($node) && $node->hasField($this->config->get('referenceField')));
+      if (empty($node)) {
+        return FALSE;
+      }
+      foreach ($this->config->get('referenceFields') as $field) {
+        if ($node->hasField($field)) {
+          return TRUE;
+        }
+      }
     }
   }
 
@@ -76,17 +83,18 @@ public function build(RouteMatchInterface $route_match) {
     $nid = $route_match->getRawParameters()->get('node');
     $node = $this->nodeStorage->load($nid);
     $breadcrumb = new Breadcrumb();
+    $breadcrumb->addCacheableDependency($this->config);
     $breadcrumb->addLink(Link::createFromRoute($this->t('Home'), '<front>'));
 
-    $chain = array_reverse($this->utils->findAncestors($node, [$this->config->get('referenceField')], $this->config->get('maxDepth')));
+    $chain = array_reverse($this->utils->findAncestors($node, $this->config->get('referenceFields'), $this->config->get('maxDepth')));
 
     // XXX: Handle a looping breadcrumb scenario by filtering the present
     // node out and then optionally re-adding it after if set to do so.
     $chain = array_filter($chain, function ($link) use ($nid) {
       return $link !== $nid;
     });
     if ($this->config->get('includeSelf')) {
-      array_push($chain, $node);
+      array_push($chain, $nid);
     }
     $breadcrumb->addCacheableDependency($node);
 

src/IslandoraUtils.php

@@ -714,7 +714,7 @@ public function findAncestors(ContentEntityInterface $entity, array $fields = [s
    * @param int $current_height
    *   The current height of the recursion.
    */
-  protected function findAncestorsByEntityReference(ContentEntityInterface $entity, array &$context, array $fields = [self::MEMBER_OF_FIELD], int $current_height = 0): void {
+  protected function findAncestorsByEntityReference(ContentEntityInterface $entity, array &$context, array $fields = [self::MEMBER_OF_FIELD], int $current_height = 1): void {
     $parents = $this->getParentsByEntityReference($entity, $fields);
     foreach ($parents as $parent) {
       if (isset($context['ancestors'][$parent->id()])) {