title: Can I save and query tags in firebase
body: <p>What are the ways to save tags to records in firebase. For example I have a user who has favourites and he/she can add multiple tags to the favourite. I would like to be able to query by one or more of the tags?</p>
  
  <p>This is the basic structure</p>
  
  <pre><code>Users{
   favourites: {
     fav_1:{
          tags:[tag1,tag2,tag3,...]
     }
     fav_2:{
          tags:[tag1,tag2,...]
     }
  
     .....
   }
  </code></pre>
  
  <p>}</p>