Allowing persistent route parameters to be overridden by setting to `…

…null`.

libraries/lithium/net/http/Router.php

@@ -127,13 +127,17 @@ public static function match($options = array(), $context = null) {
 			unset($options[0]);
 			$options = $params + $options;
 		}
-		$defaults = array('action' => 'index');
 
 		if ($context && isset($context->persist)) {
 			foreach ($context->persist as $key) {
-				$defaults[$key] = $context->params[$key];
+				$options += array($key => $context->params[$key]);
+				if ($options[$key] === null) {
+					unset($options[$key]);
+				}
 			}
 		}
+
+		$defaults = array('action' => 'index');
 		$options += $defaults;
 		$base = isset($context) ? $context->env('base') : '';
 

libraries/lithium/tests/cases/net/http/RouterTest.php

@@ -387,6 +387,31 @@ public function testParameterPersistence() {
 		$this->assertEqual('/add/baz/dib', $path);
 	}
 
+	/**
+	 * Tests that persistent parameters can be overridden with nulled-out values.
+	 *
+	 * @return void
+	 */
+	public function testOverridingPersistentParameters() {
+		Router::connect(
+			'/admin/{:controller}/{:action}',
+			array('admin' => true),
+			array('persist' => array('admin', 'controller'))
+		);
+		Router::connect('/{:controller}/{:action}');
+
+		$request = Router::process(new Request(array('url' => '/admin/posts/add', 'base' => '')));
+		$expected = array('controller' => 'posts', 'action' => 'add', 'admin' => true);
+		$this->assertEqual($expected, $request->params);
+		$this->assertEqual(array('admin', 'controller'), $request->persist);
+
+		$url = Router::match(array('action' => 'archive'), $request);
+		$this->assertEqual('/admin/posts/archive', $url);
+
+		$url = Router::match(array('action' => 'archive', 'admin' => null), $request);
+		$this->assertEqual('/posts/archive', $url);
+	}
+
 	/**
 	 * Tests passing a closure handler to `Router::connect()` to bypass or augment default
 	 * dispatching.