title: Default value for input with simple_form
body: <p><strong>im trying to do default value for input</strong></p>
  
  <p>works ok:</p>
  
  <pre><code>&lt;%= f.input_field :quantity, default: '1' %&gt; 
  </code></pre>
  
  <p>but i need f.input not f.input_field</p>
  
  <pre><code>&lt;%= f.input :quantity %&gt; 
  </code></pre>
  
  <p><br /></p>
  
  <ul>
  <li><p>im trying it with standard html value - but after unsucessfull validation quantity is overriden by 1 - undesired</p>
  
  <pre><code>&lt;%= f.input :quantity, input_html: {value: '1'} %&gt;
  </code></pre></li>
  <li><p>when i remove value and validation is unsucessfull quantity is populated - everything is ok</p>
  
  <pre><code>&lt;%= f.input :quantity %&gt;
  </code></pre></li>
  </ul>
  
  <p><strong>how to solve this ? 
  is there any alternative like in f.input_field - :default ?
  or there is any other solution with value ?</strong> </p>