title: Symfony 4 -- Form min max validation
body: <p>How to be sure that min &lt; max before validation</p>
  
  <p>here my entity </p>
  
  <pre><code>/**
   * @var int
   *
   * @ORM\Column(name="min", type="integer", nullable=true)
   */
  private $min;
  
  /**
   * @var int
   *
   * @ORM\Column(name="max", type="integer", nullable=true)
   */
  private $max;
  </code></pre>
  
  <p>in the form :</p>
  
  <pre><code>  -&gt;add('min',               NumberType::class,array('required' =&gt; false))
    -&gt;add('max',               NumberType::class,array('required' =&gt; false))
  </code></pre>
  
  <p>it's an option and min must be inferior to max before validating the form</p>
  
  <p>How can i verify and send a message to the user to change his form if it's not correct.</p>
  
  <p>Thanks</p>