title: How to indicate the parent of an object in a parent/child relationship, with Tire
body: <p>I have 2 models, <code>Player</code> and <code>Item</code>. A <code>player</code> has many <code>items</code>.</p>
  
  <p>The mapping of the <code>Item</code> model:</p>
  
  <pre><code>tire do
    mapping(
      _parent: { type: 'player' },
      _routing: { required: true, path: :user }
    ) do
  
    indexes :user, type: "string", index: :not_analyzed
  
  end
  </code></pre>
  
  <p>(not sure what the <code>path</code> option is, except that it might be used to store the items on different shards?</p>
  
  <p><strong>What I can't figure out is how to specify the <code>player</code> (parent) when saving an <code>item</code></strong>. In all the parent/child relationship examples I find on the web, they just use CURL:</p>
  
  <pre><code>curl -XPOST localhost:9200/authors/book/1?parent=2 -d '{
    "name": "Revelation Space",
    "genre": "scifi",
    "publisher": "penguin"
   }'
  </code></pre>