Issue #2668678 by yongt9412: Make paragraphs widget the default for paragraphs fields

paragraphs.module

@@ -75,6 +75,33 @@ function paragraphs_theme_suggestions_paragraph(array $variables) {
   return $suggestions;
 }
 
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function paragraphs_form_entity_form_display_edit_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
+  $field_definitions = \Drupal::service('entity_field.manager')->getFieldDefinitions($form['#entity_type'], $form['#bundle']);
+  // Loop over ERR field's display options with paragraph target type.
+  foreach (array_keys($field_definitions) as $field_name) {
+    if ($field_definitions[$field_name]->getType() == 'entity_reference_revisions') {
+      if ($field_definitions[$field_name]->getSettings()['target_type'] == 'paragraph') {
+        foreach (['options_buttons', 'options_select', 'entity_reference_revisions_autocomplete'] as $option) {
+          unset($form['fields'][$field_name]['plugin']['type']['#options'][$option]);
+        }
+      }
+    }
+  }
+}
+
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function paragraphs_form_field_storage_config_edit_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
+  if ($form_state->getFormObject()->getEntity()->getType() == 'entity_reference') {
+    // Entity Reference fields are no longer supported to reference Paragraphs.
+    unset($form['settings']['target_type']['#options'][(string) t('Content')]['paragraph']);
+  }
+}
+
 /**
  * Prepares variables for paragraph templates.
  *

src/Tests/ParagraphsAdministrationTest.php

@@ -440,6 +440,23 @@ class ParagraphsAdministrationTest extends WebTestBase {
     $this->drupalPostForm(NULL, $edit, t('Save and publish'));
     $this->assertRaw('<em class="placeholder">test required</em> has been created.');
     $this->assertNoRaw('This value should not be null.');
+
+    // Test that unsupported widgets are not displayed.
+    $this->drupalGet('admin/structure/types/manage/article/form-display');
+    $select = $this->xpath('//*[@id="edit-fields-field-paragraphs-type"]')[0];
+    $this->assertEqual(count($select->option), 2);
+    $this->assertRaw('value="entity_reference_paragraphs" selected="selected"');
+
+    // Check that Paragraphs is not displayed as an entity_reference field
+    // reference option.
+    $this->drupalGet('admin/structure/types/manage/article/fields/add-field');
+    $edit = [
+      'new_storage_type' => 'entity_reference',
+      'label' => 'unsupported field',
+      'field_name' => 'unsupportedfield',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save and continue'));
+    $this->assertNoOption('edit-settings-target-type', 'paragraph');
   }
 
   /**