diff --git a/JsonHelper.php b/JsonHelper.php
new file mode 100644
index 0000000..354d085
--- /dev/null
+++ b/JsonHelper.php
@@ -0,0 +1,22 @@
+<?php
+
+class JsonHelper
+{
+	/**
+	 * @param $array "A array where value extracted from"
+	 * @param $path "Path indicates the path to extract value"
+	 * @return mixed "the extracted value, maybe null"
+	 */
+	public static function extractValue($array, $path)
+	{
+		foreach (explode('.', $path) as $key) {
+			if (is_null($array)) break;
+			try {
+				$array = $array[$key];
+			} catch (Exception $e) {
+				$array = null;
+			}
+		}
+		return $array;
+	}
+}
\ No newline at end of file
diff --git a/README.md b/README.md
index 9327732..d445565 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,30 @@ $wgOAuth2Client['configuration']['username'] = 'username'; // JSON path to usern
 $wgOAuth2Client['configuration']['email'] = 'email'; // JSON path to email
 ```
 
+The JSON path should be set to point to the appropriate attributes in the JSON.
+
+If the properties you want from your JSON object are nested, you can use periods.
+
+For example, if user JSON is
+
+```
+{
+    "user": {
+        "username": "my username",
+        "email": "my email"
+    }
+}
+```
+
+Then your JSON path configuration should be these
+
+```
+$wgOAuth2Client['configuration']['username'] = 'user.username'; // JSON path to username
+$wgOAuth2Client['configuration']['email'] = 'user.email'; // JSON path to email
+```
+
+You can see [Json Helper Test case](./tests/phpunit/JsonHelperTest.php) for more.
+
 The **Redirect URI** for your wiki should be:
 
 ```
diff --git a/SpecialOAuth2Client.php b/SpecialOAuth2Client.php
index 35e5f4b..0c71116 100644
--- a/SpecialOAuth2Client.php
+++ b/SpecialOAuth2Client.php
@@ -17,6 +17,7 @@
 if ( !defined( 'MEDIAWIKI' ) ) {
 	die( 'This is a MediaWiki extension, and must be run from within MediaWiki.' );
 }
+require __DIR__.'/JsonHelper.php';
 
 class SpecialOAuth2Client extends SpecialPage {
 
@@ -142,8 +143,8 @@ private function _default(){
 	protected function _userHandling( $response ) {
 		global $wgOAuth2Client, $wgAuth, $wgRequest;
 
-		$username = $response['user'][$wgOAuth2Client['configuration']['username']];
-		$email = $response['user'][$wgOAuth2Client['configuration']['email']];
+		$username = JsonHelper::extractValue($response, $wgOAuth2Client['configuration']['username']);
+		$email =  JsonHelper::extractValue($response, $wgOAuth2Client['configuration']['email']);
 
 		$user = User::newFromName($username, 'creatable');
 		if (!$user) {
diff --git a/tests/phpunit/JsonHelperTest.php b/tests/phpunit/JsonHelperTest.php
new file mode 100644
index 0000000..b2a2bbb
--- /dev/null
+++ b/tests/phpunit/JsonHelperTest.php
@@ -0,0 +1,31 @@
+<?php
+
+require __DIR__ . '/../../JsonHelper.php';
+
+class JsonHelperTest extends MediaWikiTestCase
+{
+	protected function setUp()
+	{
+		parent::setUp();
+	}
+
+	public function testExtractValue()
+	{
+		$json_array = array(
+			"user" => array(
+				"username" => "username",
+				"email" => "localhost@email.com"
+			)
+		);
+		self::assertEquals("localhost@email.com", JsonHelper::extractValue($json_array, "user.email"));
+		self::assertEquals("username", JsonHelper::extractValue($json_array, "user.username"));
+		self::assertEquals("username", JsonHelper::extractValue($json_array, "user")["username"]);
+		self::assertNull(JsonHelper::extractValue($json_array, "user.emails"));
+		self::assertNull(JsonHelper::extractValue($json_array, "$.user.email"));
+	}
+
+	protected function tearDown()
+	{
+		parent::tearDown();
+	}
+}