mongodbupdate多层嵌套数组

mongodbupdate多层嵌套数组，This is more or less my current schema:

{ "_id" : 1
  "user_id": 1,
  "message" : "Yes"
  "translations" : [
    { 
      "destination" : "fr",
      "text": "Oui",
      "rating" : [
        { "user_id" : 1,
          "rating" : 1
        },
        { "user_id" : 2,
          "rating" : 1
        }
      ]
    }
  ]
}

这个更新语句会报错，目前不支持多个$占位符

db.getCollection('message').update({
    '_id': 1,
    'translations.destination': 'fr',
    'translations.rating.user_id':'1'
},
{
    '$set': {
        "translations.$.rating.$.rating": 5
    }
}

最好修改数据格式，采用key-value格式

{ "_id" : 1
  "user_id": 1,
  "message" : "Yes"
  "translations" : {
    "fr": { 
      "destination" : "fr",
      "text": "Oui",
      "rating" : [
        { "user_id" : 1,
          "rating" : 1
        },
        { "user_id" : 2,
          "rating" : 1
        }
      }
    },
    "en": {...}
  ]
}

这样就可以更新了

“translations.fr.rating.$.rating”: 5

方法来自于 https://pythonolyk.wordpress.com/2016/01/17/mongodb-update-nested-array-using-positional-operator/