DMZ 1.7.1 (DataMapper OverZealous Edition)

[eluser]OverZealous[/eluser]
@tomdelonge
A self relationship is just a named relationship. Do you understand how multiple relationships to the same object work? IE: the creater/editor relationship from Bug to User?

For self relationships, you are just relating one object to itself.

Remember, all relationships have to be described from both sides. other_field literally is just the name of the other (opposite) field in the relationship. Notice in the example below how the relationship key and other_field are just swapped between the two definitions.

Here's some (untested) code:

Code:

class Category extends DataMapper {
    $has_one = array(
        // NOTE: can't use the keyword 'parent' here, because it has meaning to DMZ.
        'parentcategory' => array(
            'class' => 'category',
            'other_field' => 'childcategory'
        )
    );

    $has_many = array(
        'childcategory' => array(
            'class' => 'category',
            'other_field' => 'parentcategory'
        )
    );
}

You only need the categories table:

Code:

categories
---+-----------+------------------
id | name      | parentcategory_id
---+-----------+------------------
1  | ROOT      | NULL
2  | Games     | 1
3  | Work      | 1
4  | Board     | 2

Usage:

Code:

$root = new Category(1);
// create new category
$cat = new Category();
$cat->name = 'Private';
// there are actually 3 ways to save the relationship.  See Save in the manual for other examples.
$cat->save(array('parentcategory' => $root));

// get root categories
$cats = $root->childcategory->get();
foreach($cats as $c) {
    echo($c->name . "\n");
    // recurse
    foreach($c->childcategory->get() as $sub) {
        echo("    - " . $sub->name . "\n");
    }
}

// delete a child category
$root->delete_childcategory($cat);

It's really that simple, especially for $has_one self relationships. Feel free to choose better (shorter) names.

----------

One more option, you can use a simpler relationship name on one side of the relationship, like so:

Code:

$has_one = array('category' => array('other_field' => 'child'));
$has_many = array('child' => array('class' => 'category', 'other_field' => 'category'));

// table
id | name | category_id

// usage example
$cat->save_category($root);

But that can be confusing.

Who says I don't have time to answer questions?