database.rules.json

{
  "rules": {
    "rooms": {
      "$room_id": {
        ".read": "auth !== null",
        ".write": "auth !== null",
        "selectedVoteOptionsKey": {
          ".validate": "newData.isString()"
        },
        "startTime": {
          ".validate": "newData.isNumber()"
        },
        "endTime": {
          ".validate": "newData.isNumber()"
        },
        "voteOptionsList": {
          "$optionsId": {
            "$optionId": {
              ".validate": "newData.isNumber()"
            }
          }
        },
        "users": {
          "$uid": {
            "name": {
              ".validate": "$uid === auth.uid && newData.isString() && newData.val().length <= 16"
            },
            "hasVoted": {
              ".validate": "$uid === auth.uid || newData.val() === false"
            },
            "vote": {
              ".validate": "$uid === auth.uid"
            }
          }
        },
        "$other": {
          ".validate": false
        }
      }
    },
    "$other": {
      ".validate": false
    }
  }
}