I have Project Pages, which can have assigned one Mentor, and multpile Participants as DataObjects.
Each Mentor,Participant have multiple images.
Almost similar to posts above, just i'm using HasOneDOM and HasManyDOM

Geting error:

[User Error] Couldn't run query: SELECT "Participant"."ClassName", "Participant"."Created", "Participant"."LastEdited", "Participant"."FullName", "Participant"."PictureID", "Participant"."ID", CASE WHEN "Participant"."ClassName" IS NOT NULL THEN "Participant"."ClassName" ELSE 'Participant' END AS "RecordClassName" FROM "Participant" WHERE ("" = '7') ORDER BY Created DESC Unknown column '' in 'where clause'

It somehow doesn't make relations Participant=>something?

==========Project Page============

class Project extends Page
{
   static $has_one = array (
      'Mentor' => 'Mentor'
   );
   static $has_many = array (
      'Participants' => 'Participant'
   );

   function getCMSFields()
   {
      $fields = parent::getCMSFields();
 
      $participants = new HasManyDataObjectManager(
        $this,
        'Participants',
        'Participant',
        array(
            'FullName'=>'FullName'
        )
       );
 
      $mentor = new HasOneDataObjectManager(
        $this,
        'Mentor',
        'Mentor',
        array(
            'FullName'=>'FullName'
        )
      );

      $fields->addFieldToTab('Root.Content.Mentor', $mentor);
      $fields->addFieldToTab('Root.Content.Participants', $participants);
      return $fields;
   }
}

==========Participant Page============

class Participant extends DataObject
{
   static $db = array (
      'FullName' => 'Text'
   );
 
   static $has_one = array(
      'Picture'=>'ImageResource'
   );
 
   static $has_many = array (
      'Projects' => 'Project',
      'Images' => 'ImageResource'
   );
   public function getCMSFields()
   {
      return new FieldSet(
         new TextField('FullName'),
         new SimpleImageField('Picture'),
         new FileDataObjectManager(
            $this,
            'Images',
            'ImageResource',
            'Attachment',
             array(
                  'Description'=>'Description'
            )
         )
      );
   }
}

==========Mentor Page============
Same as Participant
==========End Mentor Page============

==========ImageResourcePage Page============

class ImageResource extends DataObject {
            static $db = array(
               'Description'=>'Text'
           ;
           static $has_one = array(
               'Attachment'=>'Image',
               'Mentor'=>'Mentor',
               'Participant'=>'Participant'
           );
           public function getCMSFields() {
               return new FieldSet(
                      new TextField('Description'),
                      new FileIFrameField('Attachment')
               );
           }
    }

==========End ImageResourcePage Page============

Totaly lost in space...

Any pointers on this still appreciated. ....