Modelling a Chat like Application in Firebase

Question

I have a Firebase database structuring question. My scenario is close to a chat application. Here are the specifics

- users(node storing several users of the app)
  - id1
      name: John
  - id2
      name: Meg
  - id2
      name: Kelly
- messages(node storing messages between two users)
  - message1
      from: id1
      to: id2
      text: ''
  - message2
      from: id3
      to: id1
      text: ''

Now imagine building a conversations view for an individual user. So I want to fetch all messages from that particular user and to that particular user

I am writing it as follows right now:

let fromMessagesRef = firebase.database().ref('messages').orderByChild('from').equalTo(firebase.auth().currentUser.uid)
fromMessagesRef.once("value").then((snapshot) => {/* do something here*/})

let toMessagesRef = firebase.database().ref('messages').orderByChild('to').equalTo(firebase.auth().currentUser.uid)
toMessagesRef.once("value").then((snapshot) => {/* do something here*/})

Questions:

1. Is this the right way to model the problem?
2. If yes, is there a way to combine the above 2 queries?

Answer 1

I would store the data like this:

- users(node storing several users of the app)
  - id1
      name: John
      messages
        message1: true
        message2: true
  - id2
      name: Meg
      messages
        message1: true
        message3: true
  - id3
      name: Kelly
      messages
        message2: true
        message3:true
- messages(node storing messages between two users)
  - message1
      from: id1
      to: id2
      text: ''
  - message2
      from: id3
      to: id1
      text: ''
  - message3
      from: id2
      to: id3
      text: ''

Firebase recommends storing things like this. So in your case your query would be

let fromMessagesRef = firebase.database().child('users').child(firebase.auth().currentUser.uid).child('messages')

This allows it to be very fast as there is no orderBy being done. Then you would loop over each message and get it's profile from the messages node.