title: ReactJS: Get multiple checkboxes value with material-ui
body: <p>How to get multiple checkboxes value ? Ref not working in material ui checkbox, no idea why.</p>
  
  <pre><code>&lt;Checkbox key={i} label={catagory.name} ref="categories" value={catagory_name} name="category"  /&gt;
  </code></pre>
  
  <p>for example : <a href="https://i.stack.imgur.com/JjCsp.png" rel="nofollow noreferrer">example</a></p>
  
  <p>Without material-ui you can get the value by ref, but with material-ui it require another method to get checkbox value. </p>
  
  <p>I get the data from API, so it will add more from time to time. How to get the value? What function I should write? Anyone know ?</p>