Okay so I have got a question too for a change:
Can anybody think of a solution that is not Cloud functions for the following scenario:
My permissions to the users collection are shown in the image below.
What I want to do is run a query of the type count to check if [value returned from that count] >= 1 on the displayname of a user. But the user is NOT authenticated at that point of time (it should be before log in). So querying user collection with authenticated user wont work. Also users collection wont work.
Ive wrapped my head around this and of course was thinking: cloud function. And that works. And its okay. But for some reason...I thought maybe there is another possibility? So I decided to ask around maybe some of you have a sleight of mind?