firebase rules, create an user PERMISSION_DENIED: Permission denied - firebase

Question

I get PERMISSION_DENIED: Permission denied when try to create an user:
{
"rules": {
".read": true,
".write": "auth != null",
"users": {
"$uid": {
".read": true,
".write": "auth.uid == $uid",
".validate": "
newData.child('user').isString() &&
newData.child('user').val().length > 3
"
}
}
}
}
user is string, has more than 3 letters. But I think it has something to do with the id.
I create an user with createUserWithEmailAndPassword and try to insert it on database:
firebase.database().ref('users/' + userID).set({
username: username,
email: email
});
The userID is the id createUserWithEmailAndPassword returns...
Any ideas what is wrong?

Answer 1

You problem comes from the .validate part: with your rules you need to write a node as follows
firebase.database().ref('users/' + userID).set({
user: username, // <-- see here we have a user sub-node
email: email
});
Or you need to change your rules as follows:
{
"rules": {
".read": true,
".write": "auth != null",
"users": {
"$uid": {
".read": true,
".write": "auth.uid == $uid",
".validate": "
newData.child('username').isString() &&
newData.child('username').val().length > 3
"
}
}
}
}