framework/validators/Validator.php
protected function formatMessage($message, $params)
    {
        if (Yii::$app !== null) {
            return \Yii::$app->getI18n()->format($message, $params, Yii::$app->language);
        }

        $placeholders = [];
        foreach ((array) $params as $name => $value) {
            $placeholders['{' . $name . '}'] = $value;
        }

        return ($placeholders === []) ? $message : strtr($message, $placeholders);
    }
protected function formatMessage($message, $params)
    {
        if (Yii::$app !== null) {
            return \Yii::$app->getI18n()->format($message, $params, Yii::$app->language);
        }

        $placeholders = [];
        foreach ((array) $params as $name => $value) {
            $placeholders['{' . $name . '}'] = $value;
        }

        return ($placeholders === []) ? $message : strtr($message, $placeholders);
    }
Formats a mesage using the I18N, or simple strtr if `\Yii::$app` is not available.
@param string $message
@param array $params
@since 2.0.12
@return string