如何在mongo$regex中添加特殊字符

db.users.findOne({"username" : {$regex : ".*son.*"}});

问题是我想寻找“\r”并且我能找到它,我知道它在那里,所以我做了:

db.users.findOne({"username" : {$regex : ".*\r.*"}});

它不起作用,我该怎么解决这个问题?

示例文档:

{
    "personId" : 1,
    "personName" : "john",
    "address" : {
        "city" : "Rue Neuve 2\\r\\rue Pré-du-Mar \\r ché 1 1003 Lausanne",
        "street" : "",
        "zipCode" : "",
        "streetNumber" : ""
    }
}

db.users.findOne({"address.city" : {$regex : ".*\r.*"}});

也尝试过:

db.users.findOne({"address.city" : {$regex : ".*\\r.*"}});