How to update old data with new data in Firebase?

Question

I'm developing a chat app. In my app there are 4 nodes called User, Recent, Message, Group. I'm using Objective-C My message object looks like,

{
    "createdAt" : 1.486618017521277E9,
    "groupId" : "-KcWKeXXQ9tjYsYfCknx",
    "objectId" : "-KcWKftK8GiMxxAnarL5",
    "senderId" : "828949592937598976",
    "senderImage" : "http://hairstyleonpoint.com/wp-content/uploads/2014/10/marcello-alvarez.png",
    "senderName" : "John Doee",
    "status" : "Seen",
    "text" : "Hi all",
    "type" : "text",
    "updatedAt" : 1.486622011467733E9
}

When I'm updating a User, all message's senderName should be updated accordingly. Is there are way to do this via the code or Do I need to write a rule. I'm a newbie to the firebase. Please suggest me a way to do that. If It's possible to do with the rules, Please guide me on this.

You'll have to update it manually. There is no code that will do it for you. — Mathew Berg, Feb 09 '17 at 13:01
See my answer here for the possible approaches: http://stackoverflow.com/questions/30693785/how-to-write-denormalized-data-in-firebase/30699277#30699277. The answer is for JavaScript, but the approaches are valid on any platform. — Frank van Puffelen, Feb 09 '17 at 14:47

score 2 · Accepted Answer · answered Feb 09 '17 at 13:34

It's not possible to do this via rules, so you have to manually iterate over all your data and update the senderName.

Anyways, I think you would probably be better off with saving {senderID: $someUserID} instead - like you would do in a relational database. The userID is static, so can change the user without having to update all the instances where you use it.

How to update old data with new data in Firebase?

1 Answers1