Fixes #957: Json::encode() doesn't handle empty object correctly.

framework/yii/helpers/BaseJson.php

@@ -81,32 +81,26 @@ class BaseJson
 	 */
 	protected static function processData($data, &$expressions, $expPrefix)
 	{
-		if (is_array($data)) {
-			foreach ($data as $key => $value) {
-				if (is_array($value) || is_object($value)) {
-					$data[$key] = static::processData($value, $expressions, $expPrefix);
-				}
-			}
-			return $data;
-		} elseif (is_object($data)) {
+		if (is_object($data)) {
 			if ($data instanceof JsExpression) {
 				$token = "!{[$expPrefix=" . count($expressions) . ']}!';
 				$expressions['"' . $token . '"'] = $data->expression;
 				return $token;
-			} else {
+			}
 			$data = $data instanceof Arrayable ? $data->toArray() : get_object_vars($data);
-				$result = array();
+			if ($data === array() && !$data instanceof Arrayable) {
+				return new \stdClass();
+			}
+		}
+
+		if (is_array($data)) {
 			foreach ($data as $key => $value) {
 				if (is_array($value) || is_object($value)) {
-						$result[$key] = static::processData($value, $expressions, $expPrefix);
-					} else {
-						$result[$key] = $value;
+					$data[$key] = static::processData($value, $expressions, $expPrefix);
 				}
 			}
-				return $result;
 		}
-		} else {
+
 		return $data;
 	}
-	}
 }

tests/unit/framework/helpers/JsonTest.php

@@ -45,6 +45,10 @@ class JsonTest extends TestCase
 			'b' => new JsExpression($expression2),
 		);
 		$this->assertSame("{\"a\":[1,$expression1],\"b\":$expression2}", Json::encode($data));
+
+		// https://github.com/yiisoft/yii2/issues/957
+		$data = (object)null;
+		$this->assertSame('{}', Json::encode($data));
 	}
 
 	public function testDecode()