<?php
class OpinionObject extends DataObject {

   public static $db = array(
      'Project' => 'Text',      //Project Name
      'Headline' => 'Text',
      'Opinion' => 'HTMLText',
      'PLink' => 'Text'         //Project Link
   );

   public static $has_one = array(
      'OpinionPage' => 'OpinionPage',
      'Client' => 'ClientObject'
   );

   public static $has_many = array(
      'Clients' => 'ClientObject'
   );

   public function getCMSFields_forPopup() {
      $map = array();
      if($set = DataObject::get("ClientObject")) {
         $map = $set->toDropdownMap('ID','Name');
      }
      return new FieldSet(
      new TextField('Headline', 'Überschrift der Kundenmeinung'),
          new TextField('Project', 'Name des Projekts'),
         new SimpleTSimpleTinyMCEField('Opinion', 'Kundenmeinung'),
         new TextField('PLink', 'Link zum Projekt'),
         new DropdownField('ClientID', 'Client', $map)
      );
    }
   
}
?>

<?php
class OpinionPage extends Page {

   public static $db = array(
      'TitleO' => 'Text'
   );

   public static $has_many = array(
      'Opinions' => 'OpinionObject',
   );
   
   function getCMSFields() {
      $fields = parent::getCMSFields();
      $fields->removeFieldFromTab('Root.Content.Main', 'Content');
      $fields->addFieldToTab('Root.Content.Opinions', new TextField('TitleO', 'Überschrift'));
      $fields->addFieldToTab('Root.Content.Opinions', new DataObjectManager($this, 'Opinions', 'OpinionObject', array('Headline' => 'Überschrift', 'Project' => 'Projekt', 'Plink' => 'Link zum Projekt'), 'getCMSFields_forPopup'));
      return $fields;
   }

}
class OpinionPage_Controller extends Page_Controller {

}