title: Populating RecyclerView with two sets of data from Firebase
body: <p>I have Firebase set up as so...</p>
  
  <pre><code>{
    "items" : {
      "-LDJak_gdBhZQ0NSB-7B" : { //item
        "name" : "Test123",
         ...
      },
      ...
    },
    "likes" : {
      "YoTjkR2ORlcr5hGedzQs5xOK2VE3" : { //user
        "-LDJiY0YSraa_RhxVWXL" : true //whether or not the item is liked
      },
      ...
    }
  }
  </code></pre>
  
  <p>And I'm populating a <code>RecyclerView</code> with items, but I need to know if each item has been liked by the current user. I know I could store each user who has liked an item in the item itself, but that seems like too much repetition. But even if done that way, I'd have to check through a list of users who liked an item for that specific user, for each item added. Should I just live with all of this repetition or is there an easy way to deal with this? Here's the code I have that uses <code>FirebaseRecyclerAdapter</code>:</p>
  
  <pre><code>private fun setUpFirebaseAdapter() {
          val ref = FirebaseDatabase.getInstance().reference
  
          val itemQuery = ref
                  .child("items")
                  .limitToLast(20)
  
          val itemOptions = FirebaseRecyclerOptions.Builder&lt;Item&gt;()
                  .setQuery(itemQuery, Item::class.java)
                  .build()
  
  
          firebaseAdapter = object : FirebaseRecyclerAdapter&lt;Item, FirebaseViewHolder&gt;(itemOptions) {
  
              override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FirebaseViewHolder {
                  val view = LayoutInflater.from(parent.context)
                          .inflate(R.layout.item_row, parent, false)
  
                  return FirebaseViewHolder(view)
              }
  
              override fun onBindViewHolder(holder: FirebaseViewHolder, position: Int, model: Item) {
                  holder.bindItems(model)
                  //...
              }
          }
      }
  </code></pre>
  
  <p>I know there's index support, but I think that would only allow me to only return liked items.</p>