Decent data structure for Firebase messaging? - firebase

Question

I'm trying to get started with Firebase and I just want to make sure that this data structure is optimized for Firebase.
The conversation object/tree/whatever looks like this:
conversations: {
"-JRHTHaKuITFIhnj02kE": {
user_one_id: "054bd9ea-5e05-442b-a03d-4ff8e763030b",
user_two_id: "0b1b89b7-2580-4d39-ae6e-22ba6773e004",
user_one_name: "Christina",
user_two_name: "Conor",
user_one_typing: false,
user_two_typing: false,
last_message_text: "Hey girl, what are you doing?",
last_message_type: "TEXT",
last_message_date: 0
}
}
and the messages object looks like so:
messages: {
"-JRHTHaKuITFIhnj02kE": {
conversation: "-JRHTHaKuITFIhnj02kE",
sender: "054bd9ea-5e05-442b-a03d-4ff8e763030b",
message: "Hey girl, what are you doing?",
message_type: "TEXT",
message_date: 0
}
}
Is storing the name relative to the user in the conversation object needed, or can I easily look up the name of the user by the users UID on the fly? Other than the name question, is this good? I don't want to get started with a really bad data structure.
Note: Yes, i know the UID for the conversation & message are the same, I got tired of making up variables.

Answer 1

I usually model the data that I need to show in a single screen in a single location in the database. That makes it possible to retrieve that data with a single read/listener.
Following that train of thought it makes sense to keep the user name in the conversation node. In fact, I usually keep the username in each message node too. The latter prevents the need for a lookup, although in this case I might be expanding the data model a bit far for the sake of keep the code as simple as possible.
For the naming of the chat: if this is a fairly standard chat app, then user may expect to have a persistent 1:1 chat with each other, so that every time you and I chat, we end up in the same room. A good approach for accomplishing that in the data model, can be found in this answer: Best way to manage Chat channels in Firebase

Answer 2

I don't think you structured it right. You should bare in mind "What if" complete analysis.
Though, I would recommend structuring it this way (I made it up for fun, not really tested in-terms of performance when getting a huge traffic. but you can always do denormalization to increase performance when needed):
{
"conversation-messages" : {
"--JpntMPN_iPC3pKDUX9Z" : {
"-Jpnjg_7eom7pMG6LDe1" : {
"message" : "hey! Who are you?",
"timestamp" : 1432165992987,
"type" : "text",
"userId" : "user:-Jpnjcdp6YXM0auS1BAT"
},
"-JpnjibdwWpf1k-zS3SD" : {
"message" : "Arya Stark. You?",
"timestamp" : 1432166001453,
"type" : "text",
"userId" : "user:-OuJffgdYY0jshTFD"
},
"-JpnkqRjkz5oT9sTrKYU" : {
"message" : "no one. a man has no name.",
"timestamp" : 1432166295571,
"type" : "text",
"userId" : "user:-Jpnjcdp6YXM0auS1BAT"
}
}
},
"conversations-metadata" : { // to show the conversation list from all users for each user
"-JpntMPN_iPC3pKDUX9Z" : {
"id": "-JpntMPN_iPC3pKDUX9Z",
"date":995043959933,
"lastMsg": "no one. a man has no name.",
"messages_id": "-JpntMPN_iPC3pKDUX9Z"
}
},
"users" : {
"user:-Jpnjcdp6YXM0auS1BAT" : {
"id" : "user:-Jpnjcdp6YXM0auS1BAT",
"name" : "many-faced foo",
"ProfileImg" : "...."
"conversations":{
"user:-Yabba_Dabba_Doo" : {
"conversation_id": "-JpntMPN_iPC3pKDUX9Z",
"read" : false
}
}
},
"user:-Yabba_Dabba_Doo" : {
"id" : "user:-Yabba_Dabba_Doo",
"name" : "Arya Stark",
"ProfileImg" : "...."
"conversations":{
"user:-Jpnjcdp6YXM0auS1BAT" : {
"conversation_id": "-JpntMPN_iPC3pKDUX9Z",
"read" : true
}
}
}
}
}