Adding and “.indexOn”: “.value” into Firebase Rules

Question

I\'m studying AngularJS and Firebase and I\'m playing with a simple ChatApp, just to understand the code.

My Firebase DB structure is like this:

\"chat\"         


        

Answer 1

To index this structure to allow efficient querying, you have to add an index for each user:

{
    "rules": {
        "chat": {
            "rooms": {
                ".indexOn": ["users/user1", "users/user2"]
            }
        }
    }
}

That won't be maintainable, since you're likely adding users dynamically.

As usual with NoSQL databases, this means you have to expand/adapt your data model to allow the use-case you want. Instead of querying the rooms for their users, keep a list of the rooms for each user (in addition to your current data):

"user_rooms": {
  "user1": {
    "chat1": true
  },
  "user2": {
    "chat1": true,
    "chat2": true
  }
  "user3": {
    "chat2": true
  }

Now you can look up the chat rooms for a user without even needing to query.

Also see my answer about this categorization problem in Firebase query if child of child contains a value.