Adds ConditionalRenderer field group plugin.

extra_fields_collection.info.yml

@@ -5,3 +5,4 @@ core: 8.x
 package: extra_field
 dependencies:
   - extra_field
+  - field_group

src/Plugin/field_group/FieldGroupFormatter/ConditionalRenderer.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace Drupal\extra_fields_collection\Plugin\field_group\FieldGroupFormatter;
+
+use Drupal\field_group\FieldGroupFormatterBase;
+
+/**
+ * Conditional renderer field group element.
+ *
+ * @FieldGroupFormatter(
+ *   id = "conditional_renderer",
+ *   label = @Translation("Conditional Renderer"),
+ *   description = @Translation("Renders the first not empty field added to the group"),
+ *   supported_contexts = {
+ *     "form",
+ *     "view"
+ *   }
+ * )
+ */
+class ConditionalRenderer extends FieldGroupFormatterBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function preRender(&$element, $rendering_object) {
+    parent::preRender($element, $rendering_object);
+    $this->filterElements($element, $rendering_object);
+  }
+
+  /**
+   * Let's to print the first field with value.
+   *
+   * @param $element
+   *   The render element.
+   * @param $rendering_object
+   *   The rendering object information.
+   */
+  public function filterElements(&$element, $rendering_object) {
+    if (isset($this->group->children)) {
+      $keep_field = [];
+      $entity = $rendering_object['#entity'];
+      foreach ($this->group->children as $field_name) {
+        if (isset($element[$field_name]) && ($entity->hasField($field_name) && !empty($entity->get($field_name)->getValue()))) {
+          // Save the field name and stop the loop.
+          $keep_field[] = $field_name;
+          break 1;
+        }
+      }
+      $hide_fields = array_diff($this->group->children, $keep_field);
+      foreach ($hide_fields as $field_name) {
+        // Keep the field but disable the access.
+        $element[$field_name]['#access'] = FALSE;
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsForm() {
+    $form = parent::settingsForm();
+    unset($form['id']);
+    unset($form['classes']);
+    return $form;
+  }
+
+}