framework/web/JsonParser.php
public function parse($rawBody, $contentType)
    {
        try {
            $parameters = Json::decode($rawBody, $this->asArray);
            return $parameters === null ? [] : $parameters;
        } catch (InvalidArgumentException $e) {
            if ($this->throwException) {
                throw new BadRequestHttpException('Invalid JSON data in request body: ' . $e->getMessage());
            }

            return [];
        }
    }
public function parse($rawBody, $contentType)
    {
        try {
            $parameters = Json::decode($rawBody, $this->asArray);
            return $parameters === null ? [] : $parameters;
        } catch (InvalidArgumentException $e) {
            if ($this->throwException) {
                throw new BadRequestHttpException('Invalid JSON data in request body: ' . $e->getMessage());
            }

            return [];
        }
    }
Parses a HTTP request body.
@param string $rawBody the raw HTTP request body.
@param string $contentType the content type specified for the request body.
@return array parameters parsed from the request body
@throws BadRequestHttpException if the body contains invalid json and [[throwException]] is `true`.