title: Many to many without crud
body: <p>How to make a form for adding users, which have roles, I want to use something like in yabe example, but without crud...</p>
  
  <pre><code>User:
  @ManyToMany(cascade=CascadeType.ALL)
  public Set&lt;Role&gt; roles = new HashSet();
  
  Role: 
  @ManyToMany(mappedBy="roles")
  public Set&lt;User&gt; users = new HashSet&lt;User&gt;();
  
  #{field 'user.email'}
  &lt;input id="${field.id}" name= "${field.name}" class="element text" maxlength="255" size="20" value="${field.value}"/&gt;
  #{/field}
  ...
  &lt;select multiple name="roles"&gt;
  #{field 'user.roles'}
  &lt;option value="admin"&gt;admin&lt;/option&gt;
  &lt;option value="user"&gt;user&lt;/option&gt;
  #{/field}
  &lt;/select&gt;
  </code></pre>