在数组mongodb中查找

Question

嗨，我想任命所有spécifique用户名，我尝试了很多方法StackOverflowlink，但没有一个起作用 有什么帮助吗？

[
    {
        "_id": "5ce64339b8a8a83c40949a09",
        "creator": "5cde6bad979baf2518ac14fb",
        "dateRDV": "2019-05-24",
        "rDVS": [
            {
                "_id": "5ce64339dfac7e2fe0cb8400",
                "timeRDV": "9",
                "username": "aaaa"
            },
            {
                "_id": "5ce644f5dfac7e2fe0cb8401",
                "timeRDV": "10",
                "username": "bb"
            },
            ......
        ]
    }