title: How to add placeholder on input in Symfony 4 form?
body: <p>In my Symfony 4 form, I am try to get a placeholder for my input. I tried the below but I get an error that it is not allowed. Any ideas how else I can achieve this?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>        -&gt;add('firstname', TextType::class, ['label' =&gt; 'Vorname ', 'placeholder' =&gt; 'Your name',])</code></pre>
  </div>
  </div>
  </p>
  
  <p>As suggested in the <a href="https://symfony.com/doc/current/reference/forms/types/text.html#attr" rel="noreferrer">documentation</a> I have also tried the below, here I am not getting an error, just nothing is rendering. </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>        -&gt;add('firstname', TextType::class, ['label' =&gt; 'Vorname '], ['attr' =&gt; ['placeholder' =&gt; 'Vorname ']])</code></pre>
  </div>
  </div>
  </p>