title: Validate field input is string laravel
body: <p>In the documentation I saw this</p>
  
  <pre><code>string:value
  
  The field under validation must be a string type.
  </code></pre>
  
  <p>But as I understand (from the scarce explanation + the example given) I must validate with a certain string value. But what I want is to validate simply that the input value contains just letters from the alphabet.</p>
  
  <p>Apparently</p>
  
  <pre><code>'name'  =&gt; 'required|string'
  </code></pre>
  
  <p>won't cut it, because it has to be <code>string:SomeValue</code></p>
  
  <p>So, what is the correct way, to set a validation rule <strong><em>In the model class</em></strong> that validates against string?</p>