Issue #2757317 by mglaman, moshe weitzman, bojanz: Provide field formatter to...

Issue #2757317 by mglaman, moshe weitzman, bojanz: Provide field formatter to provide transitions as actionable buttons

src/Form/StateTransitionForm.php

+<?php
+
+namespace Drupal\state_machine\Form;
+
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+class StateTransitionForm extends FormBase {
+
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
+  /**
+   * The entity.
+   *
+   * @var \Drupal\Core\Entity\FieldableEntityInterface
+   */
+  protected $entity;
+
+  /**
+   * Constructs a new StateTransitionForm object.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *    The entity type manager.
+   */
+  public function __construct(EntityTypeManagerInterface $entity_type_manager) {
+    $this->entityTypeManager = $entity_type_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('entity_type.manager')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'state_machine_state_transition_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $field_name = $form_state->get('field_name');
+    $entity_type = $form_state->get('entity_type');
+    $entity_id = $form_state->get('entity_id');
+    $this->entity = $this->entityTypeManager->getStorage($entity_type)->load($entity_id);
+    /** @var \Drupal\state_machine\Plugin\Field\FieldType\StateItemInterface $state_item */
+    $state_item = $this->entity->get($field_name)->first();
+
+    $form['actions'] = [
+      '#type' => 'container',
+    ];
+    foreach ($state_item->getTransitions() as $transition_id => $transition) {
+      $form['actions'][$transition_id] = [
+        '#type' => 'submit',
+        '#value' => $transition->getLabel(),
+        '#submit' => ['::submitForm'],
+        '#transition' => $transition,
+      ];
+    }
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $triggering_element = $form_state->getTriggeringElement();
+    /** @var \Drupal\state_machine\Plugin\Field\FieldType\StateItemInterface $state_item */
+    $state_item = $this->entity->get($form_state->get('field_name'))->first();
+    $state_item->applyTransition($triggering_element['#transition']);
+    $this->entity->save();
+  }
+
+}

src/Plugin/Field/FieldFormatter/StateTransitionFormFormatter.php

+<?php
+
+namespace Drupal\state_machine\Plugin\Field\FieldFormatter;
+
+use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Field\FormatterBase;
+use Drupal\Core\Form\FormBuilderInterface;
+use Drupal\Core\Form\FormState;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\state_machine\Form\StateTransitionForm;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Plugin implementation of the 'state_transition_form' formatter.
+ *
+ * @FieldFormatter(
+ *   id = "state_transition_form",
+ *   label = @Translation("Transition form"),
+ *   field_types = {
+ *     "state",
+ *   },
+ * )
+ */
+class StateTransitionFormFormatter extends FormatterBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * The form builder.
+   *
+   * @var \Drupal\Core\Form\FormBuilderInterface
+   */
+  protected $formBuilder;
+
+  /**
+   * Constructs a new StateTransitionFormFormatter object.
+   *
+   * @param string $plugin_id
+   *   The plugin_id for the formatter.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
+   *   The definition of the field to which the formatter is associated.
+   * @param array $settings
+   *   The formatter settings.
+   * @param string $label
+   *   The formatter label display setting.
+   * @param string $view_mode
+   *   The view mode.
+   * @param array $third_party_settings
+   *   Any third party settings.
+   * @param \Drupal\Core\Form\FormBuilderInterface $form_builder
+   *   The form builder.
+   */
+  public function __construct($plugin_id, $plugin_definition, FieldDefinitionInterface $field_definition, array $settings, $label, $view_mode, array $third_party_settings, FormBuilderInterface $form_builder) {
+    parent::__construct($plugin_id, $plugin_definition, $field_definition, $settings, $label, $view_mode, $third_party_settings);
+
+    $this->formBuilder = $form_builder;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $plugin_id,
+      $plugin_definition,
+      $configuration['field_definition'],
+      $configuration['settings'],
+      $configuration['label'],
+      $configuration['view_mode'],
+      $configuration['third_party_settings'],
+      $container->get('form_builder')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function viewElements(FieldItemListInterface $items, $langcode) {
+    // Do not show the form if the user isn't allowed to modify the entity.
+    if (!$items->getEntity()->access('update')) {
+      return [];
+    }
+
+    $form_state = (new FormState())->setFormState([
+      'entity_type' => $items->getEntity()->getEntityTypeId(),
+      'entity_id' => $items->getEntity()->id(),
+      'field_name' => $items->getFieldDefinition()->getName()
+    ]);
+    // $elements needs a value for each delta. State fields can't be multivalue,
+    // so it's safe to hardcode 0.
+    $elements = [];
+    $elements[0] = $this->formBuilder->buildForm(StateTransitionForm::class, $form_state);
+
+    return $elements;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function isApplicable(FieldDefinitionInterface $field_definition) {
+    return $field_definition->getType() == 'state';
+  }
+
+}