Fix scoped query parameters not being merged into pagination URLs

Existing query parameters in the active scope should be present in
generated pagination URLs. This fixes pagination URLs 'dropping' scoped
parameters.

Refs #9210

src/View/Helper/PaginatorHelper.php

@@ -505,9 +505,16 @@ class PaginatorHelper extends Helper
             $url['sort'] = $url['direction'] = null;
         }
         if (!empty($paging['scope'])) {
-            $url = [$paging['scope'] => $url] + $this->_config['options']['url'];
-            if (empty($url[$paging['scope']]['page'])) {
-                unset($url[$paging['scope']]['page']);
+            $scope = $paging['scope'];
+            $currentParams = $this->_config['options']['url'];
+            // Merge existing query parameters in the scope.
+            if (isset($currentParams['?'][$scope]) && is_array($currentParams['?'][$scope])) {
+                $url += $currentParams['?'][$scope];
+                unset($currentParams['?'][$scope]);
+            }
+            $url = [$scope => $url] + $currentParams;
+            if (empty($url[$scope]['page'])) {
+                unset($url[$scope]['page']);
             }
         }
 

tests/TestCase/View/Helper/PaginatorHelperTest.php

@@ -827,6 +827,38 @@ class PaginatorHelperTest extends TestCase
     }
 
     /**
+     * test generateUrl with multiple pagination and query string values
+     *
+     * @return void
+     */
+    public function testGenerateUrlMultiplePaginationQueryStringData()
+    {
+        Router::setRequestInfo([
+            ['controller' => 'posts', 'action' => 'index', 'plugin' => null],
+            ['base' => '', 'here' => 'posts/index', 'webroot' => '/']
+        ]);
+        $this->View->request->params['paging']['Article']['scope'] = 'article';
+        $this->View->request->params['paging']['Article']['page'] = 3;
+        $this->View->request->params['paging']['Article']['prevPage'] = true;
+        $this->View->request->query = [
+            'article' => [
+                'puppy' => 'no'
+            ]
+        ];
+        // Need to run __construct to update _config['url']
+        $paginator = new PaginatorHelper($this->View);
+        $paginator->options(['model' => 'Article']);
+
+        $result = $paginator->generateUrl(['sort' => 'name']);
+        $expected = '/posts/index?article%5Bpage%5D=3&article%5Bsort%5D=name&article%5Bpuppy%5D=no';
+        $this->assertEquals($expected, $result);
+
+        $result = $paginator->generateUrl([]);
+        $expected = '/posts/index?article%5Bpage%5D=3&article%5Bpuppy%5D=no';
+        $this->assertEquals($expected, $result);
+    }
+
+    /**
      * testOptions method
      *
      * @return void