Firebase 规则通配符和 Child 比较

Question

我正在尝试将 Firebase 的规则通配符与 children 比较混合使用。

我正在阅读其他地方的 child，其值为“4”。

当我进行文字比较时，模拟器给了我绿灯（像这样）：

{
  "rules": {
    "die": {
      "rolls": {
        "$i": {
          ".read": "4 == root.child('die/i').val()"
        }
      },
      "i": {
        ".read": true,
        ".write": true
      }
    }
  }
}

输出（成功）：

Type    read
Location    /die/rolls/4
Data    null
Auth    null
Read successful
Line 7 (/die/rolls/4)
read: "4 == root.child('die/i').val()"

但是通配符比较失败。为什么？

{
  "rules": {
    "die": {
      "rolls": {
        "$i": {
          ".read": "$i == root.child('die/i').val()"
        }
      },
      "i": {
        ".read": true,
        ".write": true
      }
    }
  }
}

输出（失败）：

Type    read
Location    /die/rolls/4
Data    null
Auth    null
Read denied
Line 7 (/die/rolls/4)
read: "$i == root.child('die/i').val()"

（另外，我试过模拟身份验证；同样的事情。）

Answer 1

失败的原因是

root.child('die/i').val()

returns一个数字。根据 firebase 文档

Note: Path keys are always strings. For this reason, it's important to keep in mind that when we attempt to compare a $ variable to a number, this will always fail. This can be corrected by converting the number to a string (e.g. $key === newData.val()+'')

以下是您想要的结果

 {
 "rules": {
   "die": {
     "rolls": {
       "$i": {
         ".read": "$i === root.child('die/i').val()+''"
       }
     },
     "i": {
       ".read": true,
       ".write": true
     }
   }
 }
}

Firebase documentation

Firebase 规则通配符和 Child 比较

Firebase Rules Wildcard and Child comparison

real-time

wildcard

firebase

firebase-security

firebase-realtime-database