Attempting to get a key where value is equal to in Realtime Database

Question

I have the following structure:

attendanceOptions: 
  uid: "specificemail@email.com",
  uid: "anotherEmail@email.com",

I'm attempting to get the key and value where value is... In example get where anotherEmail@email.com

Here is my attempt:

security rules:

{
  "rules": {
    ".read": true,
    ".write": true,
    "organization": {
      "$uid": {
        "attendanceOptions": {
          ".indexOn": ["$uid"]
        },
        "members": {
          ".indexOn": ["mStatus"]
        }
      }
    }
  }
}

The error I get is

Error saving rules - Line 9: Invalid key: $uid. Index must be either .value or declared on a valid path

Obviously I'm doing something wrong. How can I accomplish this?

Answer 1

If you want to define an index on attendanceOptions for the value of each child node, you can do that with:

"attendanceOptions": {
  ".indexOn": [".value"]
},

Also see the Firebase documentation on indexing by value.