title: Symfony : Converting ManyToMany to OneToMany / ManyToOne and keeping the multiple select in defaul form_row()
body: <p>creating a ManyToMany relation in a doctrine entity, will result in rendering as a multiple select or checkboxlist, depending on the configuration.</p>
  
  <p>I'm breaking my head over creating this while having the same relationship, but with OneToMany / ManyToOne relations. </p>
  
  <p>Consider Product > ProductColors &lt; Color. In Form type we define the ProductType with productColors as CollectionType, referencing the ProductColorsType. In ProductColorsType we define the EntityType to the entity class Color. This will result in the form_row creating multiple rows, each having a single select with the color options. </p>
  
  <p>Creating a ManyToMany Product - Colors, and setting Color to EntityType, with multiple to true will result in a multiple select.</p>
  
  <p>How can i set this relation in the FormTypes, so the OneToMany / ManyToOne behaves the same as setting a ManyToMany?</p>