Unable to remove Firebase node - firebase

Question

I'm at a loss on this one. I'm unable to delete a node in Firebase either from the web app or through the Firebase console. When the /courses/{courseId}/members/{uid} node is removed, either through set(null) or remove(), the user's information is added immediately.
I do have two cloud functions updating the seats node so we can keep track of space, but neither of those point at the ../{uid} endpoint. I've also gone through my web app code to make sure there were no on_delete events writing to the tree. Any clues as to what's happening?
UPDATE
After going backward in my commit tree, I was able to confirm that it was the below cloud function disallowing deletes from the tree. So, my question now becomes, what in this function causing the behavior? I can't see anything that would re-write data. My database structure is below.
/courses ref
courses: {
someStringId1234: {
members: {
uid12345: {
code: 'someString',
email: 'some#email.com'
},
uid67890: { ... }
},
seats: 10
},
{ ... }
}
This cloud function watches for changes to the uid item. It grabs the parent node (members) and then updates the count in seats. For some reason, this is re-writing the previously deleted key and setting it to 0.
countRegistrations, firebase cloud function
exports.countRegistrations = functions.database.ref('/courses/{courseId}/members/{uid}').onWrite(
(change) => {
// get the `members` node for the item
const collectionRef = change.after.ref.parent;
console.log('collectionRef', collectionRef)
// get the `seats` key for updating
const countRef = collectionRef.parent.child('seats');
console.log('countRef', countRef)
let increment;
// If the ID is there after but not before, remove one seat
if (change.after.exists() && !change.before.exists()) {
increment = -1;
// if the ID is not there after, but there before, add one seat
} else if (!change.after.exists() && change.before.exists()) {
increment = 1;
} else {
// Nothing to change
return null;
}
// Return the promise from countRef.transaction() so the function
// waits for this async event to complete before it exits.
return countRef.transaction((current) => {
console.log('Line 38', current) // debugging, confirms the correct refs are grabbed by the function
return (current || 0) + increment;
}).then(() => {
return
});
});
Just for fun, here's what happens when I try to delete the node directly in the console. The database rules allow writing if you're logged in.

Answer 1

I had the same issue. Turns out that by deleting that node would cause too many firebase functions to execute. Try use the delete command in the CLI, it might give you more information on the error. firebase database:remove <//path to node>

Answer 2

I had same issue, and I just fixed it. The error occurred because of the node data it is using.
Please check where you use the node current, and break or sign out. Then, it is possible to delete the node.
Explanation: If the node is user info and current the user is logged in, it is impossible to delete the node. Continuously, re-created node as long as deleting node.

Answer 3

For this scenario, i am using handler to delay the refresh of my activity with 2-3 seconds, If anyone is getting this error then make sure:-
Do not make the refresh of an activity or display (reloading the database)
Use handler with 2-3 seconds delay, then the logged in user can't auto remake the node.
How i used to delete the node:-
myViewHolder.deleteicon.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String childvalue = list.get(i).getPosition();
Log.d(TAG, "onClick: "+ childvalue);
FirebaseDatabase.getInstance().getReference()
.child("Submission/Rules").child(categorynametext).child(user.getUid()).child(childvalue).removeValue()
.addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
if (task.isSuccessful()) {
Toast.makeText(context, "You have removed successfully", Toast.LENGTH_LONG).show();
try
{
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
///Here i am refreshing the activity
((Activity)context).finish();
((Activity)context).overridePendingTransition( 0, 0);
((Activity)context).startActivity(((Activity) context).getIntent());
((Activity)context).overridePendingTransition( 0, 0);
}
}, 3000);
}
catch (Exception e){
e.printStackTrace();
}
} else {
//enter msg or enter your code which you want to show in case of value is not remove properly or removed failed.
Toast.makeText(context, "There is an error while removing the rule, Please try again later", Toast.LENGTH_LONG).show();
}
}
});
}
});
UPDATE:
After working more in this, i found i was also getting the same error, because of using addValueEventListener< in this case it is auto adding the data while deleting or adding something in the database and if you use addListenerForSingleValueEvent, then there will not any problem while adding or deleting the data.
Final Conclusion:
addValueEventListener (If you want to refresh the page everytime any add or deletion occurs
addListenerForSingleValueEvent(If you don't want to refresh the page while adding or deleting something)