相关疑难解决方法(0)

我正在尝试执行"$或"搜索以匹配两个正则表达式,如下所示:

{
    "metadata.text": {
        "$or": [
            {
                "$regex": ".*hello.*"
            },
            {
                "$regex": ".*world.*"
            }
        ]
    }
}

我正在使用mlab.com并收到以下错误:

MongoDB error: "Command failed with error 2: 'unknown operator: $or' on server ZZZZZZZ. The full response is { "ok" : 0.0, "errmsg" : "unknown operator: $or", "code" : 2, "codeName" : "BadValue" }." Please contact support@mlab.com if you need assistance.

为什么$或被检测为未知运营商？