I am trying to secure my firebase database to allow the creation of new records, but not allow the deletion of existing records. Ultimately, I plan to utilise Firebase authentication in my app as well, and allow users to update existing records if they are the author, but I am trying to get the simple case working first.
However! No matter what I try in the database rules simulator, despite what the documentation seems to suggest, the value of data.exists() seems to always be true. From what I what I can understand from the documentation, the variable data represents a record in the database as it did before an operation took-place. That is to say, for creates, data would not exist, and for updates/deletes, data would refer to a real record that exists in the database. This does not seem to be the case, to the point where I am actually suspecting a bug in Firebase, as when setting the following rules on my database, all write operations are disallowed:
{
"rules": {
".read": true,
".write": "!data.exists()"
}
}
No matter what values I put into the simulator, be it Location or Data. I have even written a small EmberJS app to verify if the Simulator is telling the truth and it too, is denied permission for all write operations.
I really have no idea where to go from here as I am pretty much out of things to try. I tried deleting all records from my database, which lets the simulator think it can perform write operations, but my test app still gets PERMISSION_DENIED, so I don't know what's causing inconsistencies there.
Is my understanding of the predefined data variable correct? If so, why can't I write the rules I want? I have seen snippets literally trying to achieve my "create only, no-delete" rule that seem to line up with my understanding.
Last note: I am trying this in a totally new Firebase project with JUST the rules above, and only ~a few records of junk data laying around my database.