title: Laravel - prepopulate input data after validation failed
body: <p>I used 5.4 and I've an index action in convert controller which shows the form and then have another action calculate in the convert controller. So the form has from-currency, amount, to-currency input and all of them are required.</p>
  
  <p>Here's the validation I've for calculate action:</p>
  
  <pre><code>    $this-&gt;validate(request(), [
          'from_currency' =&gt; 'required|min:3|max:3|alpha',
          'to_currency' =&gt; 'required|min:3|max:3|alpha',
          'amount' =&gt; 'required|numeric',
      ]);
  </code></pre>
  
  <p>If the validation failed I want when showing the errors and the form it will prepopulate the input already.</p>
  
  <p>Is there like a function I can use for Request ? I know how to get the domain/path inside blade like Request::root() and I also tried Request::input('from_currency) in the view but not work.</p>
  
  <p>I even tried to set the view data like 'from_currency' => request('from_currency') and it's blank. Any idea?</p>