[Deprecated] DMZ 1.5.3 (DataMapper OverZealous Edition)

[eluser]OverZealous[/eluser]
@mcnux

With your exact examples, it's much simpler than you think. First off, though, you have to declare the relationship differently on the parent side than the child side. In DMZ, all relationships have to be specified uniquely on both sides.

To get a One-to-Many self-referencing relationship, you can keep the table structure as you have it. The "parent" is going to be called 'list_item'. The child, for the sake of example, I'll call 'sub_item'.

Then your model looks like this:

Code:

class List_item extends DataMapper{
  var $has_one = array(
    'list_item'=>array(
      'other_field'=>'sub_item'
    )
  );
  var $has_many = array(
    'sub_item'=>array(
      'class'=>'list_item'
    )
  );
}

That's it! This is almost the exact same as the example code from the manual, under Self Relationships. ;-)

Usage Examples:

Code:

$parent = new List_Item();
$parent->get_by_id($parent_id);

$child = new List_Item();
$child-> ...

// Saving, will save $child at the same time:
$child->save_list_item($parent);
// OR this also works, if $child is already saved:
$parent->save_sub_item($child);

// Accessing:
$parent->sub_item->get();
foreach($parent->sub_item as $item) {
    ...
}

If you want to keep the name "parent_list_item", then I recommend you rename the column from 'list_item_id' to 'parent_list_item_id'. It's much, much easier that way. So, your table becomes

Code:

list_items
==========
id
parent_list_item_id
whatever

And your model becomes:

Code:

class List_item extends DataMapper{
  var $has_one = array(
    'parent_list_item'=>array(
      'class' => 'list_item',
      'other_field' => 'sub_item'
    )
  );
  var $has_many = array(
    'sub_item'=>array(
      'class' => 'list_item',
      'other_field' => 'parent_list_item'
    )
  );
}

Notice how the relationship is defined from both points of view, and they are symmetric.

Usage Examples:

Code:

// Setup parent and child as before...

// Saving, will save $child at the same time:
$child->save_parent_list_item($parent);
// OR this also works, if $child is already saved:
$parent->save_sub_item($child);

// Accessing:
$parent_of_child = $child->parent_list_item->get();

If you just have to have the table named the way you did, but you still want the term 'parent_list_item', then it gets more difficult, and you have to get creative with the 'join_self_as' and 'join_other_as' fields. Just remember that they cannot be the same values.

P.S.
I should point out that you really shouldn't ever need 'join_self/other_as' in just about any system. Especially if you are designing it new. So, avoid using them if at all possible. This is me speaking from experience! ;-)