--- /dev/null
+<?php
+
+namespace Drupal\ctools\Plugin\Relationship;
+
+
+use Drupal\Core\Field\FieldItemInterface;
+use Drupal\Core\Field\TypedData\FieldItemDataDefinition;
+use Drupal\Core\Plugin\Context\Context;
+use Drupal\Core\Plugin\Context\ContextDefinition;
+use Drupal\Core\Plugin\Context\ContextInterface;
+use Drupal\Core\TypedData\DataReferenceInterface;
+use Drupal\Core\TypedData\ListInterface;
+use Drupal\ctools\Annotation\Relationship;
+use Drupal\ctools\Plugin\RelationshipBase;
+
+/**
+ * @Relationship(
+ * id = "typed_data_relationship",
+ * deriver = "\Drupal\ctools\Plugin\Deriver\TypedDataRelationshipDeriver"
+ * )
+ */
+class TypedDataRelationship extends RelationshipBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getRelationship() {
+ $plugin_definition = $this->getPluginDefinition();
+
+ $data_type = $plugin_definition['data_type'];
+ $context_definition = new ContextDefinition($data_type, $plugin_definition['label']);
+ $context_value = NULL;
+
+ // If the 'base' context has a value, then get the property value to put on
+ // the context (otherwise, mapping hasn't occurred yet and we just want to
+ // return the context with the right definition and no value).
+ if ($this->getContext('base')->hasContextValue()) {
+ $data = $this->getData($this->getContext('base'));
+ $property = $this->getMainPropertyName($data);
+ $context_value = $data->get($property)->getValue();
+ }
+
+ $context_definition->setDefaultValue($context_value);
+ return new Context($context_definition, $context_value);
+ }
+
+ public function getName() {
+ return $this->getPluginDefinition()['property_name'];
+ }
+
+ protected function getData(ContextInterface $context) {
+ /** @var \Drupal\Core\TypedData\ComplexDataInterface $base */
+ $base = $context->getContextValue();
+ $name = $this->getPluginDefinition()['property_name'];
+ $data = $base->get($name);
+ // @todo add configuration to get N instead of first.
+ if ($data instanceof ListInterface) {
+ $data = $data->first();
+ }
+ if ($data instanceof DataReferenceInterface) {
+ $data = $data->getTarget();
+ }
+ return $data;
+ }
+
+ protected function getMainPropertyName(FieldItemInterface $data) {
+ return $data->getFieldDefinition()->getFieldStorageDefinition()->getMainPropertyName();
+ }
+
+ public function getRelationshipValue() {
+ $property = $this->getMainPropertyName();
+ /** @var \Drupal\Core\TypedData\ComplexDataInterface $data */
+ $data = $this->getRelationship()->getContextData();
+ $data->get($property)->getValue();
+ }
+
+}