title: Firebase Cloud Functions Generate Push ID
body: <p>I'm writing a Firebase cloud function that creates a "Multi-player Room" object in the Real-time Database for my multi-player game. I use <code>databaseReference.push()</code> to write the room in the database with a unique ID, but I need to get that ID and store in the room object too.
  What I get:</p>
  
  <pre><code>{
     multiplayer_games:{
        -SOME_ID:{
           some_value:***,
           some_other_value:***
        }
     }
  }
  </code></pre>
  
  <p>What I need:</p>
  
  <pre><code>{
     multiplayer_games:{
        -SOME_ID:{
           id:-SOME_ID,
           some_value:***,
           some_other_value:***
        }
     }
  }
  </code></pre>
  
  <p>So how can I get that random push ID and use it?</p>