database.rules.json

{
  "rules": {
    "activity": {
      ".read": true,
      ".indexOn": "userId",
      "$id": {
      	".write": "!data.exists() && auth !== null && newData.child('userId').val() === auth.uid"
      }
    },
    "charities": {
      ".read": true,
      "$uid": {
        ".write": "$uid === auth.uid"
      }
    },
    "foodDonations": {
      ".read": true,
      "$id": {
        ".write": "auth !== null && (newData.child('donorId').val() === auth.uid || data.child('donorId').val() === auth.uid)"
      }
    },
    "nonfoodDonations": {
      ".read": true,
      "$id": {
        ".write": "auth !== null && (newData.child('donorId').val() === auth.uid || data.child('donorId').val() === auth.uid)"
      }
    },
    "reservations": {
      ".read": true,
      "$donationId": {
        ".write": "auth !== null && (!data.exists() || data.child('deliveredOrReceived').val() === false)",
        "deliveredOrReceived": {
          ".write": "(!data.exists() && newData.val() === false) || (data.exists() && data.parent().child('reserverId').val() === auth.uid && newData.val() === true)"
        },
        "reserverId": {
          ".write": "(!data.exists() && newData.val() === null) || (data.exists() && data.val() === null && newData.val() === auth.uid) || (data.exists() && newData.val() === null && data.val() === auth.uid)"
        },
        "type": {
          ".write": "(!data.exists() && newData.val() === null) || (data.exists() && data.parent().child('reserverId').val() === auth.uid) || (data.exists() && data.parent().child('reserverId').val() === null)"
        }
      }
    },
    "users": {
      ".read": false,
      "$uid": {
        ".read": "$uid === auth.uid",
        ".write": "$uid === auth.uid"
      }
    }
  }
}