Issue #1998658 by larowlan: Fixed Creating Custom Block with same name as...

Issue #1998658 by larowlan: Fixed Creating Custom Block with same name as existing block throws SQL error.

core/modules/block/custom_block/lib/Drupal/custom_block/CustomBlockFormController.php

@@ -219,4 +219,19 @@ public function delete(array $form, array &$form_state) {
     $form_state['redirect'] = array('block/' . $block->id() . '/delete', array('query' => $destination));
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, array &$form_state) {
+    if ($this->entity->isNew()) {
+      // @todo Inject this once https://drupal.org/node/2060865 is in.
+      $exists = \Drupal::entityManager()->getStorageController('custom_block')->loadByProperties(array('info' => $form_state['values']['info']));
+      if (!empty($exists)) {
+        form_set_error('info', t('A block with description %name already exists.', array(
+        '%name' => $form_state['values']['info']
+      )));
+      }
+    }
+  }
+
 }

core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php

@@ -64,6 +64,16 @@ public function testCustomBlockCreation() {
     $blocks = entity_load_multiple_by_properties('custom_block', array('info' => $edit['info']));
     $block = reset($blocks);
     $this->assertTrue($block, 'Custom Block found in database.');
+
+    // Check that attempting to create another block with the same value for
+    // 'info' returns an error.
+    $this->drupalPost('block/add/basic', $edit, t('Save'));
+
+    // Check that the Basic block has been created.
+    $this->assertRaw(format_string('A block with description %name already exists.', array(
+      '%name' => $edit["info"]
+    )));
+    $this->assertResponse(200);
   }
 
   /**