Firebase database rules "hasChildren" - firebase

Question

I was writing security rules in my database but I do not understand why the validation does not pass it ..
I just want people to be able to type in "Extra" if the key says "nombre".
In case it's not the key "nombre", don't let it.
the rules:
"rules": {
"Users": {
"$uid": {
".read": "$uid === auth.uid",
".write": "$uid === auth.uid && root.child('Users').child(auth.uid).exists() === false || newData.hasChild('Extra')",
".validate": "newData.hasChildren(['nombre'])",
"Extra":{
}
}
}
}
Is the writing rule wrong? Does someone explain to me why?
TEST1 wrong
TEST2

Answer 1

You're writing to location /Users/$uid/Extra, so the nombre property ends up in /Users/$uid/Extra/nombre. To test the rule, you'll want to write to /Users/$uid.
If instead you want to allow the JSON like this:
Users: {
myUserId: {
Extra: {
nombre: "MT Designer"
}
}
}
Then your rules currently don't work, because you're validating that nombre exissts under myUserId. It should be:
{
"rules": {
"Users": {
"$uid": {
".read": "$uid === auth.uid",
".write": "$uid === auth.uid && root.child('Users').child(auth.uid).exists() === false || newData.hasChild('Extra')",
"Extra":{
".validate": "newData.hasChildren(['nombre'])",
}
}
}
}
}
Update: 2020-07-10
From the new screenshots it seems that yyou haven't applied the change from above yet, so I'd first recommend doing that. But if you want to reject other child nodes in Extra, you can do that by changing the rules to:
"Extra":{
"nombre": {
".validate": "data.isString()"
},
"$other": {
".validate": false
},
}
So this validates that the name is a string, and rejects all other child nodes.
From comments, apparently this is what OP ended up with:
"Users": {
"$uid": {
".read": "$uid === auth.uid",
".write": "$uid === auth.uid && root.child('Users').child(auth.uid).exists() === false || newData.hasChild('Extra')",
"$othernode": {
".validate": false
},
"Extra": {
"nombre": {
".validate": "newData.isString()"
},
"$other": {
".validate": false
},
}
}
},