title: Vue.js v-bind:value to empty object
body: <p>I have a dropdown that is populated with an array of objects.</p>
  
  <pre><code>&lt;select v-model="selectedLeague" v-on:change="chooseLeague()"&gt;
      &lt;option v-for="league in model.leagues" v-bind:value="league"&gt;
          {{  league.name }}
      &lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>At initialization, selectedLeague is {}</p>
  
  <p>I want to add a default option that is selected when the object is empty. I tried adding</p>
  
  <pre><code>&lt;option disabled v-bind:value=null&gt;Choose League&lt;/option&gt;
  </code></pre>
  
  <p>But that will not work because it is never null. What can I add to check if the object is empty using data binding? I am using version 2.4.4 btw</p>