title: Update a field when another field changes
body: <p>I'm sure there's more than one way to do this, but what's a good way of updating one JSF/PrimeFaces component when another one changes?</p>
  
  <p>I've got a slider, that correctly updates an input field with it's value (including the value in the backing bean). But that value is a number, and I want to display it as a text value e.g. if it's 1, I want to display "Easy" and if it's 4, display "Difficult".</p>
  
  <p>I've got it partly working by hiding the input field that stores the numeric value. And then I've added another 'visible' outputLabel that is linked to a getter in my backing bean that translates the numbers to text values. </p>
  
  <p>But I'm not sure how to say "when the hidden field's value changes, refresh the value displayed in the outputLabel".</p>
  
  <p>Sure it's something to do with valueChangeListeners or 'update' attributes, but struggling to put it all together. </p>
  
  <p>Can anyone point me in vaguely the right direction? Not even quite sure what to Google, though I have tried.</p>
  
  <p>Thanks</p>