title: Firebase database schema
body: <p>I can't understand the way Firebase db works.
  Yes, I know it is a JSON with my data, I know the ways to set one-to-many and many-to-many relationship between different objects. But is there any way to set up some kind of "<em>schema</em>" to database?</p>
  
  <p>An example to understand what I mean: what if I'm creating an Android app, using Firebase SDK, and my friend is creating an iOS app. I'm pushing this to <code>"users": {name: John, city: LA}</code>. And my friend makes a mistake, pushing <code>{name: Tom, cety: NY}</code>. Than, trying to get Toms city - what will I get? Null?</p>
  
  <p>Is there a way to specify a structure to saved data. In Firebase console I see only way to add exact values, not specify the way it should be structured. How to tell other developers, or "<em>me-in-the-future</em>" that my users should contain, for example "name", "gender" and "dog_eyes_color"?
  Hope you understand me.</p>