mongodb 更新数组出现can't append to array using string field name

数据库内容大概如下：

{
_id:1,
"hero_list" : {   
             "15521" : {
                        "stars" : 0,
                        "_id" : 15521,
                        "equip" : [
                                [ ],
                                [ ],
                                [ ],
                                {
                                        "item_id" : 310141,
                                        "lv" : 103,
                                        "uuid" : "4a727ee1-e7b0-4265-b004-e2b75890378a",
                                        "amount" : 1
                                },
                                [ ],
                                [ ]
                        ],
                        "lv" : 15,
                        "exp" : 0,
                        "quality" : 0
                }
            }
}

> db.hero.update({_id:1},{$set:{"hero_list.15521.equip.4.lv":1}})
can't append to array using string field name [lv]

看了半天，原来是自己眼花，数组下标数错了

db.hero.update({_id:1},{$set:{"hero_list.15521.equip.3.lv":1}})

OK