I have a project where I use Firebase's real time database. The project has a lot of records so I have been using orderByChild on my queries, so I only get the records I'm interested in and not all records in the node, like so:
return this.angularFireDataBase.database.ref().child('users/').orderByChild('is_supervisor').equalTo('si');
But now I need to get records whose is_supervisor property is null or doesn't even exist. Is this possible? And how?