在Firebase中索引未知节点 [英] Indexing unknown nodes in Firebase

问题描述

我的数据结构是这样的:

My data structure is like this:

firebase-endpoint/updates/<location_id>/<update_id>

每个位置都有许多更新，firebase将这些更新添加为数组"元素.

each location has many updates that firebase adds as "array" elements.

如果在插入数据库之前未知location_id，如何在每个更新的"validFrom"属性上建立索引?

How can I index on the "validFrom" property of each update if the location_id is unknown before insertion into the databse?

{
  "rules": {
    "updates": {
      "<location_id>": { // WHAT IS THIS NODE SUPPOSED TO BE?
        ".indexOn": ["validFrom"]
      }
    }
  }
}

数据结构示例

{
    "71a57e17cbfd0f524680221b9896d88c5ab400b3": {
        "-KBHwULMDZ4EL_B48-if": {
            "place_id": "71a57e17cbfd0f524680221b9896d88c5ab400b3",
            "name": "Gymbox Bank",
            "statusValueId": 2,
            "update_id": "NOT_SET",
            "user_id": "7017a0f5-04a7-498c-9ccd-c547728deffb",
            "validFrom": 1456311760554,
            "votes": 1
        }
    },
    "d9a02ab407543155d86b84901c69797cb534ac17": {
        "-KBHgPkz_buv7DzOFHbD": {
            "place_id": "d9a02ab407543155d86b84901c69797cb534ac17",
            "name": "The Ivy Chelsea Garden",
            "update_id": "NOT_SET",
            "user_id": "7017a0f5-04a7-498c-9ccd-c547728deffb",
            "validFrom": 1456307547374,
            "votes": 0
        }
    }
}

更新:我不认为这是对上述问题的重复，因为该问题也没有具有未知ID的父对象.即<location_id>和<update_id>都是自由格式键，不能手动设置

Update: I don't think this is a dupe of the said question becauase that question doesn't have a parent object with an unknown id as well. ie both <location_id> and <update_id> are free form keys and cannot be set by hand

推荐答案

我在文档中做了更多的挖掘工作，我认为这应该可行:

I did a bit more digging in the docs and I think this should work:

{
  "rules": {
    "updates": {
      "$location_id": { // $location_id should act like a wild card
        ".indexOn": ["validFrom"]
      }
    }
  }
}

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