Binding sub property of array element in Polymer
<p>I have simple <code>iron-selector</code> and <code>dom-repeat</code>. When I change sub property of selected item <code>dom-repeat</code> is not refreshed, but item of array is updated.</p>

<pre><code>&lt;dom-module id="my-element"&gt;
  &lt;template&gt;
    &lt;iron-selector selected="{{selected}}" attr-for-selected="v"&gt;
      &lt;template is="dom-repeat" items="{{array}}"&gt;
        &lt;div v="{{item}}"&gt;{{item.summary}}&lt;/div&gt;
      &lt;/template&gt;
    &lt;/iron-selector&gt;
    &lt;paper-input label="summary" value="{{selected.summary}}"&gt;&lt;/paper-input&gt;
  &lt;/template&gt;
&lt;/dom-module&gt;

Polymer({
  is: "my-element",
  properties: {
    array: {
      type: Array,
      value: () =&gt; {
        return [{summary: '1'}, {summary: '2'}, {summary: '3'}]
      }
    }
  },
});
</code></pre>

<p><a href="https://jsfiddle.net/rudux/Lmkh03rg/2/" rel="nofollow">jsfiddle</a></p>

<p>I can not understand how bind sub-property of selected element and dom-repeat item.</p>