I have a many_many relationship that I am trying to set with a CheckboxSetField.

In my getCMSFields function I have:

$fields->addFieldToTab("Root.Vehicle", new CheckboxSetField('Categories', 'CategoryPage', $this->getCategories(), $this->CurrentCategories()));

And the corresponding functions are:

function getCategories(){
		if($Pages = DataObject::get('CategoryPage')){
		  $data = array();
		  foreach($Pages as $page){
			  $data[$page->ID] = $page->Title;
		  }
		  return $data;
		} else {
		  return array('No Objects found');
		}
	}
	
	function CurrentCategories(){
		$data = array();
		$do = CategoryPage::get()->leftJoin('ProductPage_Categories', '"CategoryPage"."ID" = "ProductPage_Categories"."CategoryPageID"')->filter(array("ProductPageID" => $this->ID));
		if($do){
			foreach($do as $cat){
				$data[$cat->ID] = $cat->ID;
			}
			return $data;
		}
	}

The categories are saving to the database no problem, but I can't get the checkboxes to display as checked. If I echo out the CurrentCategories function results the correct information is there, just not sure what I am missing to make the boxes show as checked.

Thanks