Deleting parent node with child value - swift

Question

I am struggling to overcome to issue I have. I am trying to delete a parent node/key given I find the correct child value.
My database is structure liked this
I am querying my database by a certain value, objectID, as it will match the postID which is passed through the parameters. The objectID value is removed. However, I am struggling to remove the key in which it falls under.
I have had mixed results so far:
I can either remove the objectID value using this code:
refSnap?.ref.child("objectID").child(postID).removeValue()
Of I can remove the whole notifications node/directory, using this:
refSnap?.ref.child("objectID").queryEqual(toValue: postID).ref.removeValue()
refSnap?.key gives me all the keys/nodes under the notifications node.
I cannot access the key which the objectID and all other information is stored under as it is .childByAutoId. Can anyone possibly help me as to how I can sort this issue?

Answer 1

While the other answer provides some insight with an alternate and workable structure, the ability to delete a node based on a child is fairly straightforward and directly addresses the question without changing the structure.
(note that the structure may need to be changed anyway but for this exercise, we'll use it as is.)
Given a structure suggested in the question:
notification
"rtupy..." //childByAutoId
"-LFEMjAcny..." // childByAutoId
"-LFEzrrq..." // childByAutoId
from: "aw,sdasdad"
objectID: "-LFEMjAcn...."
timestamp: 15292
type: "comment"
Suppose you want to delete the node "-LFEzrrq..." as shown in your screenshot. That node contains the child objectID: "-LFEMjAcn...."
To delete the node you need query for the node that contains the objectID you want which, according to the question, is working and returning the correct child.
Use the returned snapshot to obtain it's parent key, and get the path to that node and delete it. Note that we don't know what process or code the OP used to obtain the node they want to delete - perhaps it was from another query and the node reference was passed in or some other means.
let queryRef = //unknown how, but build the query for objectID = "-LFEMjAcny...."
queryRef.observeSingleEvent(of: .value, with: { snapshot in
let key = snapshot.key //this is the parent key of the objectID node i.e. -LFEMzrrq..."
let parentRef = snapshot.ref.parent! //this is the path to that parent
let refToDelete = parentRef.child(key) //add the parent key to the path: -LFEzrrq
refToDelete.removeValue() //delete it
})
As you can see, regardless of the parent nodes' key, or how deep it is, this code will delete the node found in the query.
The key names do not matter so using .childByAutoId as references to tie your nodes together is safe and generally best practice as disassociating node keys from the data they contain makes your structure highly expandable.

Answer 2

Your issue is that you are using childByAutoId and you can't "tie" these random alphanumerics to something(in this case the post).
The structure that i would set is this:
-notifications
--uid //notifications for user
--- userAid+userBid //follow notification, if they unfollow you already now which one it is and you can go and delete it
---commentNotificationID // you give this notification the same Id that the comment has, so if the user deletes the comment you use that id to delete the notification as well.