Issue #2216459 by sun: Add a KeyValueStoreInterface::has() method.

core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php

@@ -46,6 +46,16 @@ public function __construct($collection, Connection $connection, $table = 'key_v
     $this->table = $table;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function has($key) {
+    return (bool) $this->connection->query('SELECT 1 FROM {' . $this->connection->escapeTable($this->table) . '} WHERE collection = :collection AND name = :key', array(
+      ':collection' => $this->collection,
+      ':key' => $key,
+    ))->fetchField();
+  }
+
   /**
    * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::getMultiple().
    */

core/lib/Drupal/Core/KeyValueStore/DatabaseStorageExpirable.php

@@ -56,6 +56,17 @@ public function __construct($collection, Connection $connection, $table = 'key_v
     parent::__construct($collection, $connection, $table);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function has($key) {
+    return (bool) $this->connection->query('SELECT 1 FROM {' . $this->connection->escapeTable($this->table) . '} WHERE collection = :collection AND name = :key AND expire > :now', array(
+      ':collection' => $this->collection,
+      ':key' => $key,
+      ':now' => REQUEST_TIME,
+    ))->fetchField();
+  }
+
   /**
    * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::getMultiple().
    */

core/lib/Drupal/Core/KeyValueStore/KeyValueStoreInterface.php

@@ -20,6 +20,17 @@ interface KeyValueStoreInterface {
    */
   public function getCollectionName();
 
+  /**
+   * Returns whether a given key exists in the store.
+   *
+   * @param string $key
+   *   The key to check.
+   *
+   * @return bool
+   *   TRUE if the key exists, FALSE otherwise.
+   */
+  public function has($key);
+
   /**
    * Returns the stored value for a given key.
    *

core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php

@@ -19,6 +19,13 @@ class MemoryStorage extends StorageBase {
    */
   protected $data = array();
 
+  /**
+   * {@inheritdoc}
+   */
+  public function has($key) {
+    return array_key_exists($key, $this->data);
+  }
+
   /**
    * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::get().
    */

core/lib/Drupal/Core/KeyValueStore/NullStorageExpirable.php

@@ -33,6 +33,13 @@ public function __construct($collection) {
     $this->collection = $collection;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function has($key) {
+    return FALSE;
+  }
+
   /**
    * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::get().
    */

core/modules/system/lib/Drupal/system/Tests/KeyValueStore/DatabaseStorageExpirableTest.php

@@ -141,7 +141,9 @@ public function testExpiration() {
     $stores[0]->set('troubles', 'here to stay');
 
     // Only the non-expired item should be returned.
+    $this->assertFalse($stores[0]->has('yesterday'));
     $this->assertFalse($stores[0]->get('yesterday'));
+    $this->assertTrue($stores[0]->has('troubles'));
     $this->assertIdentical($stores[0]->get('troubles'), 'here to stay');
     $this->assertIdentical(count($stores[0]->getMultiple(array('yesterday', 'troubles'))), 1);
 

core/modules/system/lib/Drupal/system/Tests/KeyValueStore/StorageTestBase.php

@@ -83,8 +83,10 @@ public function testCRUD() {
 
     // Verify that an item can be stored.
     $stores[0]->set('foo', $this->objects[0]);
+    $this->assertTrue($stores[0]->has('foo'));
     $this->assertIdenticalObject($this->objects[0], $stores[0]->get('foo'));
     // Verify that the other collection is not affected.
+    $this->assertFalse($stores[1]->has('foo'));
     $this->assertFalse($stores[1]->get('foo'));
 
     // Verify that an item can be updated.
@@ -100,9 +102,11 @@ public function testCRUD() {
 
     // Verify that an item can be deleted.
     $stores[0]->delete('foo');
+    $this->assertFalse($stores[0]->has('foo'));
     $this->assertFalse($stores[0]->get('foo'));
 
     // Verify that the other collection is not affected.
+    $this->assertTrue($stores[1]->has('foo'));
     $this->assertIdenticalObject($this->objects[2], $stores[1]->get('foo'));
     $stores[1]->delete('foo');
     $this->assertFalse($stores[1]->get('foo'));