Firebase fanout data to update specific fields remove other siblings fields - ios

Question

Each user has a conversation node, each time a new conversation has a new message I need to update both conversation nodes for the two user involved in the conversation, I want just to update the "lastMessage" and "tinestamp" fields here is my try:
let fanoutObject = [userPath : dataToUpdate,
otherUserPath : dataToUpdate]
K.FirebaseRef.root.updateChildValues(fanoutObject)
where the paths for each user is:
"/users/{userID}/conversations/{conversationID}"
and the dataToUpdate:
let dataToUpdate:[String:AnyObject] = ["timestamp" : message.timestamp,
"lastMessage": message.textBody]
Result:
The node conversations for each user is updated BUT other fields in the conversation node are removed !
the conversation node fro each user is:
"conversations" : {
"{conversationID}" : {
"lastMessage" : "your name ?",
"seen" : true,
"timestamp" : 1467849600000,
"with" : {
"country" : "US",
"firstName" : "John",
"profileImage" : "https://..."
}
}
}
note that the node conversations is inside a node user which is an element inside the root node users
and after update it's :
"conversations" : {
"{conversationID}" : {
"lastMessage" : "your name ?",
"timestamp" : 1467849600000,
}
}
but I was expecting just to update the two values and keep others ?
According to docs my code should works:
updateChildValues Update some of the keys for a defined path without
replacing all of the data.

Answer 1

It's a bit hard to parse your code, but most likely it's the behavior of updateChildValues() that is confusing you.
When you call updateChildValues(), the Firebase server will loop over the object that you pass in. For each path in there, it will replace the entire value at that path with the value from that you passed in.
So if your current JSON is:
{
"Users": {
"uidForUser1": {
"name": "iOSGeek",
"id": 2305342
},
"uidForUser2": {
"name": "Frank van Puffelen",
"id": 209103
}
}
And the update is (in JSON format, the lingua franca of the Firebase Database):
{
"users/uidForUser2/name": "puf",
"users/uidForUser1/name": "My actual name"
}
Your resultant JSON will be:
{
"Users": {
"uidForUser1": {
"name": "My actual name",
"id": 2305342
},
"uidForUser2": {
"name": "puf",
"id": 209103
}
}
But if you send the following update:
{
"users/uidForUser1": {
"name": "My actual name"
},
"users/uidForUser2": {
"name": "puf"
}
}
The resulting JSON will be:
{
"Users": {
"uidForUser1": {
"name": "My actual name"
},
"uidForUser2": {
"name": "puf"
}
}
Update
To update two fields in the same object, but leave the other fields unmodified:
{
"path/to/object/field1": "new value",
"path/to/object/field2": "new value2"
}

Answer 2

Alternatively, you can update the lastMessage and timeStamp data by replacing the old values by providing full path :
let lastMessagePath = "/users/{userID}/conversations/{conversationID}/lastMessage"
let lastTimeStampPath = "/users/{userID}/conversations/{conversationID}/timestamp"
K.FirebaseRef.child(lastMessagePath).setValue(message.timestamp)
K.FirebaseRef.child(lastTimeStampPath).setValue(message.textBody)