src/Leevel/Http/Request.php
protected function isEmptyString(string $key): bool
    {
        $value = $this->input($key);

        return is_string($value) && '' === trim($value) && '0' !== $value;
    }
protected function isEmptyString(string $key): bool
    {
        $value = $this->input($key);

        return is_string($value) && '' === trim($value) && '0' !== $value;
    }
是否为空字符串.

@param string $key

@return bool