title: Symfony 4 - Multi assert difficults
body: <p>in my symfony project I have an entity that has this field:</p>
  
  <pre><code>/**
   * Solde
   * @ORM\Column(type="float", nullable=true)
   */
  private $solde;
  </code></pre>
  
  <p>This field can be either null, equal to 0 or greater than 0 but can not be negative.</p>
  
  <p>So I wonder how I can organize the asserts for this field?</p>
  
  <p>Can I do something like this? </p>
  
  <pre><code> /**
   * @Assert\!Negative
   */
  </code></pre>
  
  <p>Otherwise the asserts I should use would be:</p>
  
  <pre><code>/ ** 
   * @Assert \ Null () 
   * @Assert\GreaterThanOrEqual(0)
   * / 
  </code></pre>
  
  <p>But if I use both, it may be a problem because one must make sure that the value is zero, and the other must verify that it is positive or equal to 0</p>