Draft: Reverse relationships base fields

Closes #2706431

core/modules/views/src/EntityViewsData.php

@@ -348,7 +348,7 @@ public function getViewsData() {
         if ($data_table && ($table === $base_table || $table === $revision_table) && in_array($field_name, $duplicate_fields)) {
           continue;
         }
-        $this->mapFieldDefinition($table, $field_name, $field_definitions[$field_name], $table_mapping, $data[$table]);
+        $this->mapFieldDefinition($table, $field_name, $field_definitions[$field_name], $table_mapping, $data);
       }
     }
 
@@ -391,7 +391,9 @@ public function getViewsData() {
     // Add the entity type key to each table generated.
     $entity_type_id = $this->entityType->id();
     array_walk($data, function (&$table_data) use ($entity_type_id) {
-      $table_data['table']['entity type'] = $entity_type_id;
+      if (isset($table_data['table'])) {
+        $table_data['table']['entity type'] = $entity_type_id;
+      }
     });
 
     return $data;
@@ -446,11 +448,10 @@ protected function addEntityLinks(array &$data) {
    *   The field definition.
    * @param \Drupal\Core\Entity\Sql\TableMappingInterface $table_mapping
    *   The table mapping information.
-   * @param array $table_data
-   *   A reference to a specific entity table (for example data_table) inside
-   *   the views data.
+   * @param array $data
+   *   A reference to all the views data.
    */
-  protected function mapFieldDefinition($table, $field_name, FieldDefinitionInterface $field_definition, TableMappingInterface $table_mapping, &$table_data) {
+  protected function mapFieldDefinition($table, $field_name, FieldDefinitionInterface $field_definition, TableMappingInterface $table_mapping, array &$data) {
     // Create a dummy instance to retrieve property definitions.
     $field_column_mapping = $table_mapping->getColumnNames($field_name);
     $field_schema = $field_definition->getFieldStorageDefinition()->getSchema();
@@ -462,14 +463,16 @@ protected function mapFieldDefinition($table, $field_name, FieldDefinitionInterf
     //   assuming the first one is the main column. See also what the
     //   mapSingleFieldViewsData() method does with $first.
     $first = TRUE;
+    $table_data = $data[$table] ?? [];
     foreach ($field_column_mapping as $field_column_name => $schema_field_name) {
       // The fields might be defined before the actual table.
       $table_data = $table_data ?: [];
       $table_data += [$schema_field_name => []];
-      $table_data[$schema_field_name] = NestedArray::mergeDeep($table_data[$schema_field_name], $this->mapSingleFieldViewsData($table, $field_name, $field_definition_type, $field_column_name, $field_schema['columns'][$field_column_name]['type'], $first, $field_definition));
+      $table_data[$schema_field_name] = NestedArray::mergeDeep($table_data[$schema_field_name], $this->mapSingleFieldViewsData($table, $field_name, $field_definition_type, $field_column_name, $field_schema['columns'][$field_column_name]['type'], $first, $field_definition, $data));
       $table_data[$schema_field_name]['entity field'] = $field_name;
       $first = FALSE;
     }
+    $data[$table] = $table_data;
   }
 
   /**
@@ -489,11 +492,13 @@ protected function mapFieldDefinition($table, $field_name, FieldDefinitionInterf
    *   TRUE if this is the first column within the field.
    * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
    *   The field definition.
+   * @param array $data
+   *   A reference to all the views data.
    *
    * @return array
    *   The modified views data field definition.
    */
-  protected function mapSingleFieldViewsData($table, $field_name, $field_type, $column_name, $column_type, $first, FieldDefinitionInterface $field_definition) {
+  protected function mapSingleFieldViewsData($table, $field_name, $field_type, $column_name, $column_type, $first, FieldDefinitionInterface $field_definition, array &$data) {
     $views_field = [];
 
     // Provide a nicer, less verbose label for the first column within a field.
@@ -604,7 +609,7 @@ protected function mapSingleFieldViewsData($table, $field_name, $field_type, $co
     // Do post-processing for a few field types.
     $process_method = 'processViewsDataFor' . Container::camelize($field_type);
     if (method_exists($this, $process_method)) {
-      $this->{$process_method}($table, $field_definition, $views_field, $column_name);
+      $this->{$process_method}($table, $field_definition, $views_field, $column_name, $data);
     }
 
     return $views_field;
@@ -621,8 +626,10 @@ protected function mapSingleFieldViewsData($table, $field_name, $field_type, $co
    *   The views field data.
    * @param string $field_column_name
    *   The field column being processed.
+   * @param array $data
+   *   A reference to all the views data.
    */
-  protected function processViewsDataForLanguage($table, FieldDefinitionInterface $field_definition, array &$views_field, $field_column_name) {
+  protected function processViewsDataForLanguage($table, FieldDefinitionInterface $field_definition, array &$views_field, string $field_column_name, array &$data) {
     // Apply special titles for the langcode field.
     if ($field_definition->getName() == $this->entityType->getKey('langcode')) {
       if ($table == $this->entityType->getDataTable() || $table == $this->entityType->getRevisionDataTable()) {
@@ -645,8 +652,10 @@ protected function processViewsDataForLanguage($table, FieldDefinitionInterface
    *   The views field data.
    * @param string $field_column_name
    *   The field column being processed.
+   * @param array $data
+   *   A reference to all the views data.
    */
-  protected function processViewsDataForEntityReference($table, FieldDefinitionInterface $field_definition, array &$views_field, $field_column_name) {
+  protected function processViewsDataForEntityReference($table, FieldDefinitionInterface $field_definition, array &$views_field, string $field_column_name, array &$data) {
 
     // @todo Should the actual field handler respect that this just renders a
     //   number?
@@ -656,9 +665,10 @@ protected function processViewsDataForEntityReference($table, FieldDefinitionInt
 
     if ($entity_type_id = $field_definition->getItemDefinition()->getSetting('target_type')) {
       $entity_type = $this->entityTypeManager->getDefinition($entity_type_id);
+      $target_base_table = $this->getViewsTableForEntityType($entity_type);
       if ($entity_type instanceof ContentEntityType) {
         $views_field['relationship'] = [
-          'base' => $this->getViewsTableForEntityType($entity_type),
+          'base' => $target_base_table,
           'base field' => $entity_type->getKey('id'),
           'label' => $entity_type->getLabel(),
           'title' => $entity_type->getLabel(),
@@ -671,6 +681,77 @@ protected function processViewsDataForEntityReference($table, FieldDefinitionInt
         $views_field['argument']['target_entity_type_id'] = $entity_type_id;
         $views_field['filter']['id'] = 'numeric';
         $views_field['sort']['id'] = 'standard';
+
+        // Provide a reverse relationship for the entity type that is referenced
+        // by the field.
+        $args = [
+          '@label' => $entity_type->getSingularLabel(),
+          '@field_name' => $field_definition->getName(),
+          '@entity' => $this->entityType->getLabel(),
+        ];
+        $field_name = $field_definition->getName();
+        $table_mapping = $this->storage->getTableMapping();
+        $field_storage = $field_definition->getFieldStorageDefinition();
+        $revision_metadata_field_names = array_flip($this->entityType->getRevisionMetadataKeys());
+        $pseudo_field_name = 'reverse__' . $this->entityType->id() . '__' . $field_name;
+        // Note that we are adding to a table data item that may not exist
+        // yet, but views_views_data() deep-merges the data returned from
+        // entity views handlers.
+        if ($table_mapping->requiresDedicatedTableStorage($field_storage)) {
+          $data[$target_base_table][$pseudo_field_name] = [
+            // There is a bridge table.
+            // Use the entity_reverse relationship plugin.
+            'relationship' => [
+              'title' => $this->t('@entity using @field_name', $args),
+              'label' => $this->t('@field_name', ['@field_name' => $field_name]),
+              'help' => $this->t('Relate each @entity with a @field_name set to the @label.', $args),
+              'group' => $entity_type->getLabel(),
+              'id' => 'entity_reverse',
+              'base' => $this->getViewsTableForEntityType($this->entityType),
+              'base field' => $this->entityType->getKey('id'),
+              'field_name' => $field_name,
+              'field table' => $table_mapping->getFieldTableName($field_name),
+              'field field' => $table_mapping->getFieldColumnName($field_storage, 'target_id'),
+              'entity_type' => $this->entityType->id(),
+            ],
+          ];
+        }
+        elseif (isset($revision_metadata_field_names[$field_name])) {
+          // Revision metadata fields exist only on the revision table, so the
+          // relationship has to be to that rather than to the base table.
+          $revision_table = $this->entityType->getRevisionTable() ?: $this->entityType->id() . '_revision';
+
+          $data[$target_base_table][$pseudo_field_name] = [
+            'relationship' => [
+              'title' => $this->t('@entity revision using @field_name', $args),
+              'label' => $this->t('@field_name', ['@field_name' => $field_name]),
+              'help' => $this->t('Relate each @entity revision with a @field_name set to the @label.', $args),
+              'group' => $entity_type->getLabel(),
+              'id' => 'standard',
+              'relationship field' => $entity_type->getKey('id'),
+              'base' => $revision_table,
+              'base field' => $table_mapping->getFieldColumnName($field_storage, 'target_id'),
+              'entity_type' => $this->entityType->id(),
+            ],
+          ];
+        }
+        else {
+          // The data is on the base table.
+          // Use the standard relationship plugin.
+          $data[$target_base_table][$pseudo_field_name] = [
+            'relationship' => [
+              'title' => $this->t('@entity using @field_name', $args),
+              'label' => $this->t('@field_name', ['@field_name' => $field_name]),
+              'help' => $this->t('Relate each @entity with a @field_name set to the @label.', $args),
+              'group' => $entity_type->getLabel(),
+              'id' => 'standard',
+              'relationship field' => $entity_type->getKey('id'),
+              'base' => $this->getViewsTableForEntityType($this->entityType),
+              'base field' => $table_mapping->getFieldColumnName($field_storage, 'target_id'),
+              'entity_type' => $this->entityType->id(),
+            ],
+          ];
+        }
       }
       else {
         $views_field['field']['id'] = 'field';
@@ -696,8 +777,10 @@ protected function processViewsDataForEntityReference($table, FieldDefinitionInt
    *   The views field data.
    * @param string $field_column_name
    *   The field column being processed.
+   * @param array $data
+   *   A reference to all the views data.
    */
-  protected function processViewsDataForTextLong($table, FieldDefinitionInterface $field_definition, array &$views_field, $field_column_name) {
+  protected function processViewsDataForTextLong($table, FieldDefinitionInterface $field_definition, array &$views_field, string $field_column_name, array &$data) {
     // Connect the text field to its formatter.
     if ($field_column_name == 'value') {
       $views_field['field']['format'] = $field_definition->getName() . '__format';
@@ -716,8 +799,10 @@ protected function processViewsDataForTextLong($table, FieldDefinitionInterface
    *   The views field data.
    * @param string $field_column_name
    *   The field column being processed.
+   * @param array $data
+   *   A reference to all the views data.
    */
-  protected function processViewsDataForUuid($table, FieldDefinitionInterface $field_definition, array &$views_field, $field_column_name) {
+  protected function processViewsDataForUuid($table, FieldDefinitionInterface $field_definition, array &$views_field, string $field_column_name, array &$data) {
     // It does not make sense for UUID fields to be click sortable.
     $views_field['field']['click sortable'] = FALSE;
   }