Firebase - Swift - Delete a child UID from a snapshot - swift

Question

I am trying to delete up the studentUser UID from my staffUsers. The UID I want to delete is nested in the staffUsers -> studentSession1List.
I have the UID listed with A Bool of True on creation. This "studentSession1List" will have lots of studentUsers in the list. I only want the studentUser that is logged in to have their UID(55FDLm9n6LccZBB7skaCbvfSHRz1) removed from the list.
let dataref = Database.database().reference()
dataref.child("staffUsers").queryOrdered(byChild: "studentSession1List").observe(.value, with: { (snapshot) in
for snap in snapshot.children {
guard let studentUID = Auth.auth().currentUser?.uid else { return }
let snapDataSnapshot = snap as! DataSnapshot
var snapValues = snapDataSnapshot.value as? [String: AnyObject]
if var snapWithReg = snapValues?["studentSession1List"] as? [String: Bool] {
print("This is the staff member")
print(snapWithReg)
print(snapWithReg.count)
snapWithReg.removeValue(forKey: studentUID)
}
}
}) { (error) in
print(error.localizedDescription)
}
Here is the output:
Full Function for Deleting and Adding the Student
func didSelect(for cell: StudentSearchCell) {
guard let indexpath = collectionView?.indexPath(for: cell) else { return }
let staffUser = self.users[indexpath.item]
let selectedUserId = staffUser.uid
guard let studentUID = Auth.auth().currentUser?.uid else { return }
let dataRef = Database.database().reference()
dataRef.child("staffUsers").queryOrdered(byChild: "studentSession1List").observe(.value, with: { (snapshot) in
for snap in snapshot.children {
guard let studentUID = Auth.auth().currentUser?.uid else { return }
let snapDataSnapshot = snap as! DataSnapshot
var snapValues = snapDataSnapshot.value as? [String: AnyObject]
if (snapValues? ["studentSession1List"] as? [String: Bool]) != nil {
dataRef.child("staffUsers").child(snapDataSnapshot.key).child("studentSession1List").child(studentUID).removeValue(completionBlock: { (error, ref) in
if error != nil {
print("Error: \(String(describing: error))")
return
}
print("Removed successfully")
})
}
}
}) { (error) in
print(error.localizedDescription)
}
// Add student to staff list
let ref = Database.database().reference().child("staffUsers").child(selectedUserId).child("studentSession1List")
let values = [studentUID: true]
ref.updateChildValues(values) { (err, ref) in
if let err = err {
print("Failed to follow user:", err)
return
}
}
// Add selected staff to student list
let studentRef = Database.database().reference().child("studentUsers").child(studentUID).child("studentSession1List")
studentRef.removeValue()
let studentValues = [selectedUserId: true]
studentRef.updateChildValues(studentValues) { (err, studentRef) in
if let err = err {
print("Failed to follow user:", err)
return
}
}
self.navigationController?.popViewController(animated: true)
}

Answer 1

I think you need to reach the child that you want to remove using the following code and then remove it.
Edit1:
Since inside staffUsers we have keys inside which studentSession1List is present inside which the value (studentUID) is present that we want to remove, so inside your already written code I have added the new code, please check
let dataref = Database.database().reference()
dataref.child("staffUsers").queryOrdered(byChild: "studentSession1List").observe(.value, with: { (snapshot) in
for snap in snapshot.children {
guard let studentUID = Auth.auth().currentUser?.uid else { return }
let snapDataSnapshot = snap as! DataSnapshot
var snapValues = snapDataSnapshot.value as? [String: AnyObject]
if var snapWithReg = snapValues?["studentSession1List"] as? [String: Bool] {
//Added code here
dataref.child("staffUsers").child(snapDataSnapshot.key).child("studentSession1List").child(studentUID).removeValue(completionBlock: { (error, ref) in
if error != nil {
print("Error: \(error)")
return
}
print("Removed successfully")
})
}
}
}) { (error) in
print(error.localizedDescription)
}
Edit2:
To delete the code once , we can use observeSingleEvent
observeSingleEvent(of: .value, with: { (snapshot) in
}, withCancel: nil)