I searched for this question, but none of them had an answer that worked for me.
I want to make it so when a user registers an account, it checks to see if the username they have entered already exists, before creating the account. I have tried using querying in firebase, but I just can't seem to get it to work.
Here is an image of what my firebase data looks like: My firebase data tree
How would I use query to find the string for the key "username"?