Firebase check for existing email with relative/wildcard path - firebase-realtime-database

Question

Im trying to check the emails of my users in my firebase database, if their email already exists. My json looks like that:
I dont know how to get the full path to email, because every User starts with the Unique Identifier and I dont have that information. Is it possible to use a wildcard /users/*/email or something like that?
this.afdb.database.ref('users/*/email').orderByChild('email').on('value', (snapshot)=>{
console.log(snapshot);
});

Answer 1

When a Firebase Database query runs against a location, it considers each child node under that location. And for each child node you can test the value of properties at a known path under that child.
There is no support for wildcards, nor does one seem needed for your case here:
this.afdb.database.ref('users').orderByChild('email').equalTo("pqoo#poam.com").on('value', (snapshot)=>{
snapshot.forEach((child) => {
console.log(child.val());
});
});
So the two changes are:
We query location users order by email and only return nodes with value pqoo#poam.com.
There will potentially be multiple results. So the snapshot contains a list of those results. Even if there is only a single result, the snapshot will contain a list of one result. So we use snapshot.forEach(...) to loop over the results.