Class Manufacture extends DataObject {

    private static $db = array(
        'Name' => 'Varchar',
        'SortID' => 'Int'
    );

    private static $has_many = array(
        'ModelFamilies' => 'ModelFamily'
    );

    public static $summary_fields = array(
        'Name'
    );

    public function getCMSFields() {
        $fields = parent::getCMSFields();
        $fields->removeByName('SortID');

        return $fields;
    }

}


----------------------------------------------


Class ModelFamily extends DataObject {

    private static $db = array(
        'Name' => 'Varchar'
    );

    private static $has_one = array(
        'Manufacture' => 'Manufacture'
    );


    private static $has_many = array(
        'Models' => 'Model'
    );

    public static $summary_fields = array(
        'Manufacture.Name',
        'Name'
    );

}



---------------------------------------------

Class Model extends DataObject {


    private static $db = array(
        'Name' => 'Varchar'
    );

    private static $has_one = array(
        'ModelFamily' => 'ModelFamily'
    );

    private static $belongs_many_many = array(
        'Products' => 'Product'
    );

    public static $summary_fields = array(
        'ModelFamily.Manufacture.Name',
        'ModelFamily.Name',
        'Name'
    );

}




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