Hi UncleCheese,

First of all I'd like to thank you for your effort to develop this module.
I used your module and I think is fantastic.

Now I have a little problem and I need a little help.
I have created a Product object:

class Product extends DataObject
{
   static $db = array (
      "Name"         => "Text",
      "Description"   => "HTMLText",
   );
   static $has_one = array (
      "Thumbnail"   => "Image",
   );
   static $belongs_many_many = array (
      'ProductHolderPage' => 'ProductHolderPage'
   );
   

   public function getCMSFields_forPopup()
   {
      $fields = new FieldSet();
      $fields->push( new TextField('Name', 'Product name'));
      $fields->push( new ImageField(
         "Thumbnail",
         "Upload product image",
         null,
         null,
         null,
         "assets/Products/"
      ));
      $fields->push( new SimpleHTMLEditorField('Description','Product description', array ()));
      
      return $fields;
   }
   
}

and a ProductHolderPage

class ProductHolderPage extends Page
{
   static $db = array (
   );
   static $has_one = array (
   );
   static $has_many = array (
   );
   static $many_many = array (
      'Products' => 'Product'
   );
   static $icon = "themes/mpc/images/treeicons/productholder";
   static $can_be_root = false;
   static $allowed_children = "none";
      
   function getCMSFields() {
      $fields = parent::getCMSFields();
      $fields->removeFieldFromTab("Root.Content.Main","Content");
      
      # Products TAB
      $manager = new ManyManyDataObjectManager(
         $this,
         'Products',
         'Product',
         array('Name' => 'Product name'),
         'getCMSFields_forPopup'
      );
      $manager->setAddTitle('Product');
      $fields->addFieldToTab("Root.Content.Products", $manager);
      
      return $fields;
   }
   
}

Now I need to sort the Products in each ProductHolderPage not to sort the Products list.
If I add the SortableDataObject::add_sortable_class('Product'); in the mysite/_config.php I can generally sort the Product's list but this is not useful in my case.

I need to add sortOrder to the ProductHolderPage_Products table and to manage somehow in CMS.
Is this possible?

Hi UncleCheese,

Thank you a lot! I still have trouble.

I have SS 2.3.3 and DataObjectManager last version.
I added in mysite/_config.php the line:

SortableDataObject::add_sortable_many_many_relation('ProductHolderPage', 'Products');

and I changed my class:

class ProductHolderPage extends Page
{
   static $db = array (
   );
   static $has_one = array (
   );
   static $has_many = array (
   );
   static $many_many = array (
      'Products' => 'Product'
   );
   static $icon = "themes/mpc/images/treeicons/productholder";
   static $can_be_root = false;
   static $allowed_children = "none";
      
   function getCMSFields() {
      $fields = parent::getCMSFields();
      $fields->removeFieldFromTab("Root.Content.Main","Content");
      
      # Products TAB
      $manager = new ManyManyDataObjectManager(
         $this,
         'Products',
         'Product',
         array('Name' => 'Product name'),
         'getCMSFields_forPopup'
      );
      $manager->setAddTitle('Product');
      $fields->addFieldToTab("Root.Content.Products", $manager);
//      $manager->setOnlyRelated(true);
//      $manager->setPermissions(array('edit'));
//      $manager->setMarkingPermission(false);      
      return $fields;
   }
   
}

Everything it seems to be alright. I can check the "Allow drag & drop reordering" option and "Show only related records" but when I try to reorder the items, in the database the ProductHolderPage_Products table, SortOrder field, remains with the same values (0 zero default).

Do you have any idea what I'm missing here?
Thank you a lot for your help.

Thank you, Thank you, Thank you!

Now everything is working perfectly. You are the best!