title: Firebase v3 transactions and promises
body: <p>I am struggling a bit with how to handle transactions in Firebase v3.</p>
  
  <p>I tried the following:</p>
  
  <pre><code>function fbTransaction(childRef) {
      var qTrans = Q.defer();
  
      firebase.database().ref(childRef).transaction()
      .then(function(success){
          qTrans.resolve(success);
      }).catch(function(error){
          qTrans.reject(error);
      });
  
      return qTrans.promise;
  };
  </code></pre>
  
  <p>Thus I try to update the value at the location <code>childRef</code>. When I try it as I do then it does not return any promise. Basically nothing happens.</p>
  
  <p>I also tried the example from the <a href="https://firebase.google.com/docs/database/web/read-and-write#save_data_as_transactions" rel="nofollow noreferrer">Firebase docs</a>, but that keeps returning null for both <code>post</code> and <code>success</code>.</p>