title: Check-all stops working when I add v-model attribute to the checkboxes
body: <p>Check-all feature stops working when I try to get value of each checkbox in an array using v-model. I read lot of questions on different portals including stackoverflow, people are saying that v-model doesn't work with :checked attribute which I understand but could not find a solution / alternate code to make it work. </p>
  
  <p>The 1st code that I tried was to select all checkboxes using the 1st checkbox. This works well. Code below:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>new Vue({
    el: "#app",
    data: {
      selectAll:false
    },
  })</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"&gt;&lt;/script&gt;
  
  &lt;div id="app"&gt;
    &lt;label&gt;
      &lt;input type="checkbox" v-model="selectAll"&gt;
      Select all
    &lt;/label&gt;
    &lt;br&gt;
    &lt;label&gt;
      &lt;input type="checkbox" :checked="selectAll" value="Item 1"&gt;
      Item 1
    &lt;/label&gt;
    &lt;br&gt;
    &lt;label&gt;
      &lt;input type="checkbox" :checked="selectAll" value="Item 2"&gt;
      Item 2
    &lt;/label&gt;
    &lt;br&gt;
    &lt;label&gt;
      &lt;input type="checkbox" :checked="selectAll" value="Item 3"&gt;
      Item 3
    &lt;/label&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>The 2nd code that I tried was to get value of each checkbox in an array but in this case 'select all' automatically stops working. Code below:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>new Vue({
    el: "#app",
    data: {
      selectAll:false,
      eachCheckbox: [],
    },
  })</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"&gt;&lt;/script&gt;
  
  &lt;div id="app"&gt;
    &lt;label&gt;
      &lt;input type="checkbox" v-model="selectAll"&gt;
      Select all
    &lt;/label&gt;
    &lt;br&gt;
    &lt;label&gt;
      &lt;input type="checkbox" :checked="selectAll" value="Item 1" v-model="eachCheckbox"&gt;
      Item 1
    &lt;/label&gt;
    &lt;br&gt;
    &lt;label&gt;
      &lt;input type="checkbox" :checked="selectAll" value="Item 2" v-model="eachCheckbox"&gt;
      Item 2
    &lt;/label&gt;
    &lt;br&gt;
    &lt;label&gt;
      &lt;input type="checkbox" :checked="selectAll" value="Item 3" v-model="eachCheckbox"&gt;
      Item 3
    &lt;/label&gt;
    &lt;br&gt;
    Selected checkbox values: {{eachCheckbox}}
    
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>I don't know how to make this work. Can someone help please?</p>