Whitelist feature

src/Filter.php

@@ -37,6 +37,8 @@ class Filter
      */
     protected $globalChain = null;
 
+    protected $whiteList = [];
+
     /**
      * Set a filter for a value on a specific key
      *
@@ -109,7 +111,9 @@ public function addFilterRule(FilterRule $rule, $key = null)
      */
     public function filter(array $data)
     {
-        $data = $this->filterArrayWithGlobalChain($data);
+        $data = $this->filterArrayWithGlobalChain(
+            $this->applyWhiteList($data)
+        );
 
         $this->data = new Container($data);
 
@@ -118,6 +122,65 @@ public function filter(array $data)
         return $this->data->getArrayCopy();
     }
 
+    /**
+     * Set a list of keys to be returned in the end
+     *
+     * @param array $keys
+     * @return void
+     */
+    public function whiteList(array $keys)
+    {
+        $this->whiteList = $keys;
+    }
+
+    /**
+     * Purge initial fields using white list
+     *
+     * @param array $data
+     * @return array
+     */
+    protected function applyWhiteList(array $data)
+    {
+        if (empty($this->whiteList)) {
+            return $data;
+        }
+
+        $allowed = [];
+        foreach ($this->whiteList as $key) {
+            if (strpos($key, '.') !== false) {
+                $allowed = $this->deepWhitelist($key, $allowed, $data);
+            } else {
+                $allowed[$key] = $data[$key];
+            }
+        }
+
+        return $allowed;
+    }
+
+    /**
+     * Uses dot-notation to purge initial data
+     *
+     * @param string $key
+     * @param array $result
+     * @param array $data
+     * @return array
+     */
+    protected function deepWhitelist($key, array $result, array $data)
+    {
+        $parts = explode('.', $key);
+
+        $ref = &$result;
+        $dataRef = &$data;
+        foreach ($parts as $part) {
+            $ref = &$ref[$part];
+            $dataRef = &$dataRef[$part];
+        }
+
+        $ref = $dataRef;
+
+        return $result;
+    }
+
     /**
      * Filter all set fields with a global chain, recursively
      *

tests/FilterTest.php

@@ -326,4 +326,61 @@ public function testRemoveNullOnAllMultidimensionalValues()
 
         $this->assertEquals(['test2' => 'test', 'test4' => 'test'], $result);
     }
+
+    /**
+     * Ensure the filter only returns the keys we specify on white list
+     */
+    public function testFilterWithWhiteList()
+    {
+        $this->filter->whiteList(['first_name']);
+
+        $result = $this->filter->filter([
+            'first_name' => 'john',
+            'spam' => 'spam'
+        ]);
+
+        $this->assertEquals(['first_name' => 'john'], $result);
+    }
+
+    /**
+     * Ensure the filter only returns the keys we specify on white list,
+     * this time using dot notation
+     */
+    public function testFilterWithWhiteListSubArrays()
+    {
+        $this->filter->whiteList([
+            'first_name',
+            'test1',
+            'test2.test',
+            'test2.test3.test'
+        ]);
+
+        $result = $this->filter->filter([
+            'first_name' => 'john',
+            'test1' => [
+                'test' => 'hi'
+            ],
+            'test2' => [
+                'test' => 'hi test2',
+                'test3' => [
+                    'test' => 'hi inner'
+                ],
+                'spam2' => 'spam'
+            ],
+            'spam' => 'spam'
+        ]);
+
+        $this->assertEquals([
+            'first_name' => 'john',
+            'test1' => [
+                'test' => 'hi'
+            ],
+            'test2' => [
+                'test' => 'hi test2',
+                'test3' => [
+                    'test' => 'hi inner'
+                ]
+            ]
+        ], $result);
+    }
 }